I. The significance of the distribution, formation, and transformation of low-lying saline-alkali land in China The low-lying saline-alkali land in China covers an area of ​​about 450 million mu, including about 100 million mu of low-lying saline-alkali land for comprehensive development and utilization of Yiyu. It is located in the Huang-Huai-Hai Plain, the Yellow River Hetao Plain, the Northwest inland region of the arid, semi-arid and semi-humid regions in the north of the Yangtze River, and the coastal sedimentary plains from Liaoning to the Guangxi coast, including Taiwan and Hainan Island, but mainly in China. Western area. Its occurrence and development are the result of the combined effects of natural and human factors, such as climate drought, poor soil drainage, high groundwater level, large degree of mineralization, and inappropriate production measures such as irrigation and cultivation in arid and semi-arid plains. Forming. These saline-alkali lands are generally not suitable for the growth of agricultural crops, and are not even a barren land. How to comprehensively develop this generation of sleepy low-lying saline-alkali wastelands and increase the utilization of land resources. After a long-term production practice, especially by the unremitting efforts of the people in the past 20 years, the people of our country have created a set of “digging ponds to change the The successful approach of comprehensive development of low-lying saline-alkali lands in the fields of "Taiwan to control floods" and "Shang-liang-fishing" has accumulated a wealth of practical experience. Through the transformation, the tabletop can grow grain, cotton, rapeseed, melon, fruit, vegetables, tea, mulberry, fruit trees and various kinds of economic crops, and can stock livestock and raise poultry. The pond can not only play the role of draining alkaloids, but also can raise fish and water to protect the crops on the table. At the same time, it can also use ponds and ponds to grow vegetables and grass to feed vegetables and grass. , Fish farming, Livestock and poultry manure can be used for fish farming and vegetable growing, forming a multi-species species breeding, multi-level configuration, multi-level material energy cycle transformation of three-dimensional ecological tourism agriculture, to achieve a virtuous cycle of ecological environment and rolling Development. In the past, a barren land was low on saline-alkali land. “Dry grasshoppers have been harvested and the grasshoppers have been plucked, and there has been no drought or a flood of alkalis.†Now they have become park fields, standardized ponds and roads, and have become nets and trees. The "land of fish and rice" where the droughts and floods were collected has achieved remarkable economic, social, and ecological benefits, and has become a new growth point for the development of agriculture and the rural economy in low-lying saline-alkali areas. In particular, our country has a large population, with a small average cultivated area, and with a limited amount of arable land, the development of low-alkali saline-alkali land, turning waste into treasure, expanding arable land, improving land use efficiency, and ensuring food security, has Particularly important strategic significance and practical significance.
There are more than 600 km of low-lying saline-alkali lands in Yucheng and Dongying of Shandong Province. There are more than 1,000 mu of low-alkali saline-alkali land that can be developed. In practice, they summarized the successful experience of a comprehensive development of saline-alkali wasteland under the “Shinliangxiayuâ€. The province set off an upsurge in the development of low-lying saline-alkali lands. It plans to develop 400,000 mu each year. By 2010, it plans to develop an area of ​​6 million mu, and the total output value will reach 20 billion yuan. By 1997, more than 2 million mu had been developed, of which more than 100 million mu had been formed in Taitian, and there were more than 70 fish farms. Million mu of agricultural and fishery output value of 2.1 billion yuan, of which 280,000 tons fish production, income of 1.4 billion, equivalent to 350 million mu of farmland income. In Shanxi, Shanxi, Shaanxi, Inner Mongolia, Ningxia, and Gansu provinces and autonomous regions, along the low-alkali saline-alkali areas, they have also started trials and demonstrations to implement digging ponds and lift fields to transform low-lying saline-alkali lands. These areas are market-oriented and use water and soil as a means to achieve agricultural output increase, increase farmers' income, rearrange landscapes, and build a new socialist countryside. In accordance with the requirements of industrialization, the comprehensive utilization of land resources is maximized. The rate and output rate have enabled the Yellow River region to become a demonstration area for agricultural high-yield, high-quality, and high-efficiency three-dimensional eco-tourism agriculture. A new economic uplift zone has been formed. It is an important way out for the Yellow farmers to get off the poverty line and become a well-off society, forming the development of the western region. The bright spot has promoted the strong development of agriculture in the western region.
Second, the principle of reforming low-lying saline-alkaline land The principle of reconstructing low-lying saline-alkali land is to deepen the pond, raise the field, raise the land to press the alkali, dig the pond to soak the water and drain alkali, and dilute. After several years of efforts, the degree of mineralization can be gradually reduced. Excluding salinization will enable these low-lying saline-alkali lands to achieve basic desalination or total desalination. If necessary, they can be changed to fertile land or integrated agricultural operations. Therefore, the combination of fishery and fishery agriculture in ponds and fish farming, transformation of low-lying saline-alkali land in China, increase in the area of ​​agricultural arable land, improvement of land utilization, and full use of land and resources have broad prospects for development.
Third, the main technical measures for changing fishery to fish farming in a pond combined with fish farming (a) to strengthen macro guidance, local conditions, high standards, a high starting point for regional comprehensive planning, overall arrangements, rational layout, scientific design, meticulous construction;
(2) Determine the reasonable structural ratio of ponds, fields, ditches, canals, roads and forests. The ratio of ponds, ponds and canals to forests is 4:4:2. It is also possible to use multiple fish ponds and less , Or less Taitian, more fish ponds, but the proportion of ditches road forest should be about 20%.
(3) Determine the water treatment system project for reasonable alkali and alkali removal so as to accelerate the speed of soda washing and alkali discharge, so that the field surface can adapt to the growth of crops and economic crops as soon as possible, and carry out multi-operating production based on fishing.
(d) Select fish farming species adapted to saline-alkali water quality to obtain the best economic benefits of freshly-dug pond fish farming.
(5) Correctly deal with the combination of fishery and agriculture, develop fisheries-agriculture-livestock husbandry, and process multi-dimensional composite three-dimensional ecological sightseeing agriculture to achieve an outward-oriented, modernized agricultural production structure integrating cultivation, cultivation, and production, internal and foreign trade operations. It is possible to achieve a virtuous cycle of material and energy, with low input, high output, and high efficiency.
IV. Main technical measures for changing fishery to fish farming and fish farming in combination with fish farming (I) Characteristics of pond water quality in saline-alkali areas China's low-lying saline-alkali land is characterized by "drought, alfalfa, alkali, and lean." The water level and water quality in the low-lying saline-alkali area are extremely fierce with the changes of the climate. Summer rainfall is concentrated and the water level rises, which can produce seasonal desalination. In spring, autumn and winter, the rainfall is small, especially in the spring. Drought and windy, large evaporation, and salinity greatly improved. The physicochemical properties and nutrients of water quality mainly depend on the nature of the soil. The salts contained in the soil quickly dissolve into the water, while the subsurface brine oozes out, or due to insufficient supply of fresh water or long-term drought evaporation, resulting in Na+, K+, Ca++, Mg++ cations and C l-, SO2-4 The continuous improvement of the anion, CO2-3, and HCO-3 anion resulted in an increase in salinization and salinity in the water. When the general salt content in water exceeds 300-500 mg/L, the ratio of ions in water changes greatly, the proportion of HCO-3 in water decreases, and the proportion of Cl-, SO2-4 rises relatively high. Therefore, there is a high degree of salinization and salinity in water quality. In dry and rainless areas, the salt content in river water is as high as 1000-7000 mg/l. Therefore, with these salinized, highly mineralized waters, crops generally do not grow, they cannot grow crops, and they cannot even raise pure freshwater fish. Experience has shown that several freshwater fishes grown in China have poor growth when salinity is above 5 。. Such as carp larvae, the limit of adaptation to salinity is 6 ‰, then the growth of squid to adapt to the salinity of the high limit of 7 ‰ ‰ 10 ‰; carp larvae to adapt to the salinity of the limit of 5 ‰ ~ 6 ‰ 鲢 鲢 为 8 ‰~10 ‰. In theory, Cl- and SO2-4 ions are non-toxic, but in fact, in the absence of dissolved oxygen and soil-rich organic matter, sulfate can be reduced to sulphides by bacteria, and hydrogen sulfide, to fish, Poisonous. At the same time, practice and experience have also proved that under a certain alkalinity, the higher the PH value, the greater the toxicity, such as when the PH value of 10.1, the carp species in the 24-hour half-lethal concentration of 8.2 mg Equivalent/litre, and when the pH is 8.3, the concentration of 24-hour half-life salinity of the salmon species is 10.9 meq/l. Therefore, when the alkalinity is higher than 10 meq/l, the water quality must be modified to reduce the salinity before the fish can be used. Otherwise, at this high alkalinity, if the photosynthesis is strong, the PH value can be raised to 10, causing a large number of squid deaths. Under the synergistic effect of high salinity and high pH, ​​the toxicity of carbonate alkalinity is even greater. Therefore, carbonate-type semi-alkaline water has a strong poisoning effect on fish farming. In the sea salt and alkali area along the seashore, the water quality is affected by tides, and the water C l- is the most, which also has a strong poisoning effect on fish farming.
(II) Choosing salt ponds for fish farming The appropriate fish species should be adapted to local conditions. According to the specific conditions of saline and alkali degradation in different regions during the transformation of saline-alkali soil in different regions, the fish species that can be adapted to grow in this water area can be selected according to local conditions. Also consider the combination of market sales and good economic benefits. Generally during the initial period of reform, more widely salted fish species are used such as squid, barracuda, squid, tilapia, Macrobrachium rosenbergii, river crab, freshwater whitefish, leather beard bream, grass carp, and pupa, pupa, pupa. , squid, etc., with the process of row of alkali desalination, and then gradually expand the freshwater aquaculture freshwater fish species with good returns to improve economic efficiency.
(III) Renovation and Matching of Ecological Conditions for Fish Culture in Ponds in Saline and Alkaline Land
1. Deeply dig the pond and raise the saline-alkali area, which is characterized by drought, lack of water, serious leakage, large evaporation, high salinity, and high groundwater level. Therefore, in order to reduce leakage and reduce salinity, it is necessary to dig ponds and high-lift fields so that fresh water can be introduced into the pond, alkali pressure can be repeatedly reduced, alkali can be removed, and desalination can be carried out as soon as possible so as to facilitate the cultivation of crops and livestock and poultry on countertops. Kind of business, pond fish farming, the development of three-dimensional ecological agriculture. According to the principles of unified planning, reasonable layout, overall consideration and appropriate proportion, the ratio of the general pond and field is 1:1~2.5. Should vary according to the specific circumstances of each place. The ratio of ponds and fields in Shandong is generally about 1:2, and Kaifeng in Henan is about 1:2.5. The height of the table should be greater than the critical depth of underground diving, generally 1.5 to 2 meters. The slope ratio of Taitian is 1:2~2.5, and it is twisted around Taitian. It is 30 centimeters wide and 20 centimeters high, which is good for accumulating alkali and protecting pond slopes. It is usually about 1.5 meters from the underground, and 1.5~1.7 meters from Tanggu and Tianyang. The depth of the pond is 3~3.5 meters, and the depth of the fish is 2~2.5 meters. The area of ​​fish ponds ranges from 3 to 5 mu, and the area of ​​adult fish ponds is from 5 to 15 mu. The average area is about 10 mu. It is east-west and rectangular, with an aspect ratio of 5:3. The slope ratio is about 1:2.5.
2. The establishment of a reasonable drainage system in accordance with the planning, design, and strict implementation of the pond into the drainage separation, the main channel width of 10 to 12 meters, both ends of the river into the drainage gate to control the water level and direction. The ditch is high, and the ditch is lower than the bottom of the pool for easy access and drainage. At the same time, it is necessary to master digging ponds, lift surfaces, construct irrigation and drainage channels, electricity, water, and access roads, and carry out simultaneous inspections and production at the same time.
3, early open pond, rehabilitate the water according to the regional plan to implement water diversion, well drilling project, 50 acres of water with a well. Before the stocking of fish species, fresh water must be introduced repeatedly, and the salt alkalinity should be reduced after soaking. Generally, the water consumption per mu is 40-50 cubic meters. Due to the large salinity and high salinity, the discharged water cannot be introduced into fish farming.
4. After sufficient basal fertilizer is dug in the pond and rehabilitated, the organic fertilizer must be applied immediately so that the “birth pond†can be turned into a “cooked pond†as soon as possible. In general, 750-1000 kg of organic manure, such as cow dung and pig manure, per mu, and more than 1000-2000 kg, are better if there is green manure. However, alkali-tolerant plants such as Artemisia halodendron and Solanum can not be used as green manure By applying sufficient organic fertilizer, a layer of sludge can be deposited in the pond as soon as possible, and humus and other colloids in the sludge are embedded in the gaps in the soil. In this way, on the one hand it is possible to prevent the seepage effect of the sandy loam and, on the other hand, to reduce the pH of the pool water and the saline-alkaline soil and substantially isolate it from the saline-alkali soil. Therefore, this method is a key technical measure for newly reclaiming saline-alkali water quality in saline-alkaline ponds, and must be highly valued and carefully implemented.
5. The salt-tolerant, alkali-reducing green manure planted in Chipo and Chihchi is mainly planted with Sesbania, sorghum and so on. In this way, on the one hand, it is possible to prevent the seasonal return of alkali to the surface and the evaporation of groundwater. It can also loosen the soil and prevent the compaction of the soil structure, so as to desalinate and ripen the soil. On the other hand, these green crops can also be used as providing fish farming. The required green feed and green manure serve two purposes. Generally, other green feeds can be gradually cultivated after Ikebukuro and Chiba are grown for 2 to 3 years.
6. Injecting fresh water, draining water, removing silt, improving water quality in newly excavated ponds in saline-alkaline lands. In the first year of fish farming, the water quality is lean, and fresh water should be introduced frequently to drain the lower water. At the end of the year, dry old ponds should be drained. The old ponds that have been reared for 3 to 5 years have too thick silt deposits on the bottom of the pool, affecting the depth of the pool, the amount of fish loaded, and the effects of fish farming. Therefore, they should be removed. After removing excess silt, improving water quality conditions and increasing the space for fish farming, pond mud can be used as a good fertilizer for grass feed and crops on pond slopes, pond pools, and tabletops, and it can also help to change the saline-alkali soil structure. Reduce salinity.
After these general technical measures are taken, the salinity of soil can be gradually reduced. The salinity of pool water generally decreases from 4‰ in the first year to 2‰~2.5‰ in the first year and can be reduced to the second year. 1.5‰~2‰; the third year can be reduced to 1.3‰~1.5‰. The Huimin area in Shandong Province is a coastal area along the Yellow Sea with 1.2 million mu of saline-alkaline low-lying land with a groundwater level of 0.2-1 meter. The salt content in the soil is 2.69 ‰-7.43 ‰, and the alkalinity is 2-10 mg/eq. After two years of fish culture reform, the salt content decreased from 2.69‰ to 7.43‰ to 1‰ to 1.5‰, the alkalinity increased from 5~10 meq/d to 2~5 meq/l, and the PH value was generally From 7 to 8.6, other nutrient salts also meet the general requirements.
(d) Salt production ponds for fish farming in fish ponds
1. The type of ponds in the salt-alkaline ponds is modeled and divided from the production structure into four main types:
(1) The production structure pattern of the one-way cultured fish and fish stocks for simple fish farming. This model is divided into two forms: one is to stock only one species of fish in a pond, such as tilapia or Macrobrachium rosenbergii or river crab. Its method of fish farming is the same as that of general pond culture. This model is currently used less in production; the second is a one-stock or two-cultivated fish species, a variety of fish species with polyculture pond pure fish of a single fish breeding stock production structure model, U.S. experts also called the 80:20 fish farming model, with 80% of the main fish and 20% of other fish. This model is currently used more often.
(2) Fish-agricultural combination, raising-type dual stocking production structure model. This model is to raise fish in ponds (there is a single fish species to be stocked; there is also one farmed species, with multiple varieties and polycultures). Forages, vegetables and various kinds of economics are planted on Chipo, Ikoma, and countertops. Crops etc.
(3) Fish-Agriculture-Livestock and Poultry Combining, Raising-Cultivating-Cultivating ternary compound stocking production structure model, that is, based on the fish-agricultural combination and raising-species combined dual-stocking production model, further extending and increasing livestock husbandry Connotation, that is, fish farming in ponds, planting grasses and cash crops on pond slopes, pond pools, and countertops, raising livestock and poultry cattle, pigs, chickens, ducks, geese, etc As a fertilizer for planting grasses and cash crops on Chipo, Ikoma, and tabletops, ponds, ponds, and forages planted on bench surfaces, leaves, stalks, and stems of crops are used for fish farming, cattle raising, pig rearing, and raising. Goose's feedstuffs include livestock manure and grass stems and leaves, roots of crops, straw manure fish, grasses, vegetables and crops.
(4) Fish-Agriculture-Livestock and Poultry-Processing Combination, raising-species- raising-plus-combining multiple-element composite stocking production structure model. That is, on the basis of the previous model, it is further extended to increase the connotation of agricultural and sideline products processing. Processing here includes the processing of agricultural and sideline products grown on Chipo, Chiba, and countertops, such as bean curd and tofu, which are processed into soybean curd, mung bean by-products such as bean curd, and can be used for feeding fish and fertilizer.
2. Model production examples (A) Basic conditions (1) Pond conditions: Requirements of pond construction standardization, adult fish pond, rectangular, east-west direction, generally each pond area is 5 to 15 acres, an average of 10 acres, length to width ratio of 5:3 , slope ratio 1:2~3, generally 1:2.0~2.5. The water depth is 2 to 2.5 meters and the average is about 2 meters. The water source is introduced water and underground water, and some well water is supplemented.
(2) Machinery support: Generally, every 30 to 50 mu of water surface is equipped with 1 machine well and every 10 to 15 mu of water surface is equipped with an aerator or water pump. The requirements for water source, drainage, well, electricity, and road are basically complete. .
(3) Mesa: After leveling and applying basal fertilizer, the fertility is relatively sufficient. A 4-inch submersible pump is allocated for every 50 mu, which is convenient for watering and is suitable for the cultivation of various crops such as ryegrass, sudangrass, rapeseed, corn, peanut, and cotton.
(4) Livestock and Poultry: Fermentation ponds for cows, pigs, henhouses, and manures in ponds and countertops. Fermented feces can be fed into ponds and fish.
(b) Stocking mode (1) Fish-grass combination: The use of pond slopes, pond ponds, planting grasshoppers such as grasshoppers, Sudan grasses, etc., grasses and fishes, and ponds for herbivorous fishes.
1 Fish stocking mode: mainly grass carp, multi-species fish polyculture. Grass carp accounts for 50% to 70%, carp and carp accounts for 20% to 30%, carp and carp accounts for 10% to 20%.
2 Stocking densities: 800 to 1,500 tails per acre, 50 to 150 kg of fish, and 62.5 to 100 grams of tail weight.
3 feed feed: feed mainly forage, supplemented with other fine feed such as bran, not fertilize. When the artificially cultivated forage grass is insufficient, weeds are used as a supplement. The amount of feed is calculated as the weight of each 100 kg herbivorous fish. From April to May, 10 to 30 kg of fresh grass is fed daily, plus bran 3~ 5 kg; from June to September, only feed was fed, and the daily feeding amount was 30-60 kg; in October, 20-30 kg of fresh forage grass was added daily, and 2-7 kg of bran was added.
4 Test breeding results: The net production of fish was 611.67 kg (504.3-678.78 kg), including 383.54 kg (350.26-416.83 kg) of grass carp, accounting for 62.7% of the total output. Acres net profit of 1480 yuan, kilogram fish cost 2.92 yuan, input to output ratio of 1:1.84, feed ratio of forage grass 26.4 + bran 1.19.
(2) Fish-grain combination: Feeding fish with concentrate feed, mainly for cultivating edible fish.
1 Restocking mode: mainly tilapia, accounting for 70% to 80%; cockroaches and carp accounts for 10% to 15%; carp and other 10%.
2 Stocking densities: 2000 to 3000 tails per acre, of which tilapia size is 12.5-25 g/tail.
3 feeding feed: fed with compound feed, the ratio is: bean cake 15%, bran 40%, corn 40%, bean flour 5%.
4 Experimental fish rearing results: 678.75 kg (752.3-605.2 kg) of net fish production per mu, including 606.3 kg of tilapia (521.7-767.8 kg), accounting for 89% of the total production. The net profit of 2149.2 yuan, the cost of kilogramfish was 3.14 yuan, the input-output ratio was 1:1.82, and the feed coefficient was 2.17.
(3) Combination of fish and livestock: Fermentation of fish and fish by livestock and poultry excrement, and feeding of filter-feeding fish.
1 Restocking mode: filter-feeding fish (flea and squid) account for 50% to 70%; herbivorous fish (grass and cockroaches) account for 20% to 30%; omnivorous fish (flea, cockroach, tilapia) It accounts for 10%~20%.
2 stocking density: 600 ~ 800 acres of fish species, weight 60 ~ 90 kg, the average tail weight of 100 ~ 112.5 grams.
3 fertilizer feed: 1000-2000 kg of fertilizer per acre of water surface, of which: 30% for the base fertilizer, 70% for top dressing.
4 Breeding results: 357.3 kg (256.2-486.4 kg) of net fish production per mu, including 235.1 kg (210.5-346.7 kg) of carp and carp, accounting for 65.8% of total production. The profit per mu is 743.0 yuan, the cost of the kilogramfish is 2.06 yuan, and the input-output ratio is 1:1.9. Fertilizer coefficients are: wet cow dung 40, wet pig dung 25, wet chicken dung 10 (water depth 2 to 3 meters).
In the above three fish farming models, in addition to pond fish farming, crops such as wheat, corn, soybeans, vegetables and forage grasses, Sudan grass, and reeds can also be grown on the countertops, and livestock husbandry can also be cultivated, such as cow raising and raising. Pigs, broilers, etc.
For agriculture, animal husbandry and agriculture, the total output value per mu of water is 1,438 yuan and net profit is 744 yuan. The input-output ratio is 1:2.07. The yield per mu and the yield per mu were increased by 50.4% and 67.8%, respectively, when compared with that of pure fish farming; the input-output ratio increased from 1:1.21 to 1:1.80, and the production cost decreased by 37%.
After digging ponds and reducing alkali and alkali in Taitian, great achievements have been made in fishery and alkali treatment. From the results of soil composition analysis, after two years of renovation, organic matter increased from 0.563% to 1.053%, and total nitrogen increased from 0.0467% to 0.1154. %, the alkaline hydrolysis of nitrogen increased from 29.03 ppm to 35.05 ppm, the available phosphorus increased from 2.987 ppm to 8.97 ppm, and the available potassium increased from 28.93 ppm to 62.93 ppm. From the above-mentioned soil tests, we can see that, through comprehensive treatment, the production potential of low-alkali saline-alkali land reform is large, and after two years of reform, basically, it can be gradually improved, and both the pond slope and the pond can be fully utilized for planting.
V. Prevention of Fish Diseases In addition to the prevention and control of common fish diseases in freshwater fish culture, fish diseases in special conditions in fish culture in newly-digging fishponds in saline-alkali soils are mainly fish diseases related to high salinity alkalinity, such as trigeminoxin poisoning, Big Horn rickets and acute ammonia poisoning.
(a) Trigeosin poisoning
1. Symptoms: In the early stages of poisoning, diseased fish swim to the corners of the fish pond and react to external stimuli at the beginning. Later, they gradually become unresponsive. As the time for poisoning prolongs, the fish body becomes paralyzed after the pectoral fins, and the caudal, dorsal and pelvic fins cannot be placed. Although the pectoral fin can still be stroked, it cannot advance. Touch nothing. The lid, the mandible around the eyelids, the hyperemia of the body surface, the different sizes of the erythema, the difficulty in breathing, the intermittent struggle to breathe, and the loss of balance soon leads to death. Throughout the poisoning process, fish do not float, and they do not breathe on the surface of the water. Unlike simple oxygen deficiency, they cause death from breathing difficulties in paralysis. Some fish except for fin congestion, the body surface is generally not congested; some fish die open after death. If not rescued in time, it will cause the death of the whole pond fish.
2. Pathogen: Algae. Because trichophyton is a broad-salinity algae, suitable for growth and reproduction in saline-alkali waters, it grows well in bodies of water with salinity of 2 ‰ to 3 ,. The secretion of trigonous algae toxin can cause fish poisoning and death. In the body of water with a salt content of 2‰ to 5‰, the secretion of toxins is the strongest.
3. Prevention methods (1) Apply large-scale, fast-acting organic fertilizers such as chicken manure, human waste, etc. to the pond, and apply 500-800 kg per acre each time, together with the application of inorganic fertilizer, apply urea 5~8 per acre. Kilograms, or 4 to 5 kg of compound fertilizer, 5 to 7 kg of potassium dihydrogen phosphate, to increase the pond fertility, and promote the growth of other algae and zooplankton to inhibit, kill, and kill Trichophyton. Shandong Provincial Fisheries School applied 20ppm of NH4HCO3 or thiamin to treat trigeminal algae disease, with a cure rate of 90%.
(2) directly from the more fatty ponds to collect the surface of the pool of water 20 to 30 cm into the diseased fish ponds, once a day for 3 consecutive days.
(3) If there is a fresh water supply area, pool water in diseased fish ponds can be pumped out by more than half, timely inject new fresh water, and exceed the original water level by about 10 cm to maintain the balance of groundwater infiltration, and to dilute the content of saline and alkali in diseased ponds. , Destroying the proper salinity of Trigonella alkaloids, thus inhibiting and killing Trigonella alkaloids for therapeutic purposes.
2.鲤 鲤 鳋 鳋 ( ( disease (1) Symptoms: The diseased fish produce a large number of giant horns due to pupa tissue, stimulated by the worms, secrete a lot of mucus, severe tissue destruction, causing deformation, necrosis, loss of respiratory function, underwater Dissolved oxygen does not allow normal gas exchange through the helium, resulting in oxygen deprivation, severe floating heads, and even a large number of suffocation deaths. If the number of parasites is small and the illness is mild, there will normally be no acute deaths, but the body will be dark and the fish body will be lean, with slight floating heads or floating heads. At this time, if it can be treated promptly, the effect is better; if the carp suffers from severe carp, the first symptom is that a large number of clusters and floating heads occur in the hot season, similar to the state of hypoxia, especially in the windless weather, floating head The situation was even more serious. It lasted one week and started to die in large numbers. From June to August, when the water temperature is 25~26°C, it is the season when carp attacks. At the time of onset, the salinity in the water was 2‰~2.8‰, the PH value was 8~9, and the water hardness and sulfate content were both high. In the brackish water body of Tianjin, this worm is the main parasitic disease of squid, and the infection rate and infection intensity are extremely high, and the loss caused is also enormous.
(2) Pathogen: Giant Horned Owl. Giant horned owl is a unique parasitic crustacean on the scorpionfish and squid in the saltwater fish pond.
(3) Treatment: In the onset season, dipterex insects may be sprayed over the pond at a concentration of 0.25 to 0.27 ppm. The Xindi River and Yadian Reservoir in Tianjin spilled trichlorfon for several years in an epidemic season, effectively controlling the epidemic.
3. Acute ammonia poisoning (1) Cause: There are two problems in fish ponds newly excavated on the saline-alkali soil. First, there is a high salinity in the water, and the second is a thin water. Therefore, we must take measures: First, we must set alkali and reduce salinity; Second, we must apply fertilizer to fish. In general, more basal fertilizer and water are used to fish. This will not only modify saline land, but also adapt to fish farming. For general farmed fish, the general requirements are: ammonium - nitrogen 0.1 mg / l, nitrate - nitrogen 1 ~ 2 mg / l is appropriate. In the summer, salmonids allow nitrogen compounds to consist of ammonium-nitrogen 2 mg/l, nitrate-nitrogen 3 mg/l, and nitrite-nitrogen 0.1-0.2 mg/l; while in the winter, permissible The contents are: ammonium-nitrogen 1.5 mg/l, nitrate-nitrogen 3 mg/l, and nitrite-nitrogen 0.1 mg/l.
Therefore, when ammonia-nitrogen exceeds the standard, acute ammonia poisoning may occur. The safe concentration of ammonia is 0.05 milliequivalents per liter for salmonids, 0.09 milliequivalents per liter for salmon fry, and 0.054 to 0.099 milliequivalents per liter for grass carp.
2. Illness: Sick fish swim slowly or stop. Responsive, not afraid of people. The tail of trout trembles and there is obvious congestion on the body surface. Ammonia directly causes lysis of epithelial cells and hemolymph, reducing the oxygen carrying capacity of blood and reducing the respiratory function.
3. Prevention and control methods (1) To closely monitor the water quality, comprehensive consideration should be given to factors such as salinity, alkalinity, pH, and composition of plankton.
(2) If any signs are found, one must reduce the topdressing fertilizer as appropriate, and secondly, replace the pool water.
There are more than 600 km of low-lying saline-alkali lands in Yucheng and Dongying of Shandong Province. There are more than 1,000 mu of low-alkali saline-alkali land that can be developed. In practice, they summarized the successful experience of a comprehensive development of saline-alkali wasteland under the “Shinliangxiayuâ€. The province set off an upsurge in the development of low-lying saline-alkali lands. It plans to develop 400,000 mu each year. By 2010, it plans to develop an area of ​​6 million mu, and the total output value will reach 20 billion yuan. By 1997, more than 2 million mu had been developed, of which more than 100 million mu had been formed in Taitian, and there were more than 70 fish farms. Million mu of agricultural and fishery output value of 2.1 billion yuan, of which 280,000 tons fish production, income of 1.4 billion, equivalent to 350 million mu of farmland income. In Shanxi, Shanxi, Shaanxi, Inner Mongolia, Ningxia, and Gansu provinces and autonomous regions, along the low-alkali saline-alkali areas, they have also started trials and demonstrations to implement digging ponds and lift fields to transform low-lying saline-alkali lands. These areas are market-oriented and use water and soil as a means to achieve agricultural output increase, increase farmers' income, rearrange landscapes, and build a new socialist countryside. In accordance with the requirements of industrialization, the comprehensive utilization of land resources is maximized. The rate and output rate have enabled the Yellow River region to become a demonstration area for agricultural high-yield, high-quality, and high-efficiency three-dimensional eco-tourism agriculture. A new economic uplift zone has been formed. It is an important way out for the Yellow farmers to get off the poverty line and become a well-off society, forming the development of the western region. The bright spot has promoted the strong development of agriculture in the western region.
Second, the principle of reforming low-lying saline-alkaline land The principle of reconstructing low-lying saline-alkali land is to deepen the pond, raise the field, raise the land to press the alkali, dig the pond to soak the water and drain alkali, and dilute. After several years of efforts, the degree of mineralization can be gradually reduced. Excluding salinization will enable these low-lying saline-alkali lands to achieve basic desalination or total desalination. If necessary, they can be changed to fertile land or integrated agricultural operations. Therefore, the combination of fishery and fishery agriculture in ponds and fish farming, transformation of low-lying saline-alkali land in China, increase in the area of ​​agricultural arable land, improvement of land utilization, and full use of land and resources have broad prospects for development.
Third, the main technical measures for changing fishery to fish farming in a pond combined with fish farming (a) to strengthen macro guidance, local conditions, high standards, a high starting point for regional comprehensive planning, overall arrangements, rational layout, scientific design, meticulous construction;
(2) Determine the reasonable structural ratio of ponds, fields, ditches, canals, roads and forests. The ratio of ponds, ponds and canals to forests is 4:4:2. It is also possible to use multiple fish ponds and less , Or less Taitian, more fish ponds, but the proportion of ditches road forest should be about 20%.
(3) Determine the water treatment system project for reasonable alkali and alkali removal so as to accelerate the speed of soda washing and alkali discharge, so that the field surface can adapt to the growth of crops and economic crops as soon as possible, and carry out multi-operating production based on fishing.
(d) Select fish farming species adapted to saline-alkali water quality to obtain the best economic benefits of freshly-dug pond fish farming.
(5) Correctly deal with the combination of fishery and agriculture, develop fisheries-agriculture-livestock husbandry, and process multi-dimensional composite three-dimensional ecological sightseeing agriculture to achieve an outward-oriented, modernized agricultural production structure integrating cultivation, cultivation, and production, internal and foreign trade operations. It is possible to achieve a virtuous cycle of material and energy, with low input, high output, and high efficiency.
IV. Main technical measures for changing fishery to fish farming and fish farming in combination with fish farming (I) Characteristics of pond water quality in saline-alkali areas China's low-lying saline-alkali land is characterized by "drought, alfalfa, alkali, and lean." The water level and water quality in the low-lying saline-alkali area are extremely fierce with the changes of the climate. Summer rainfall is concentrated and the water level rises, which can produce seasonal desalination. In spring, autumn and winter, the rainfall is small, especially in the spring. Drought and windy, large evaporation, and salinity greatly improved. The physicochemical properties and nutrients of water quality mainly depend on the nature of the soil. The salts contained in the soil quickly dissolve into the water, while the subsurface brine oozes out, or due to insufficient supply of fresh water or long-term drought evaporation, resulting in Na+, K+, Ca++, Mg++ cations and C l-, SO2-4 The continuous improvement of the anion, CO2-3, and HCO-3 anion resulted in an increase in salinization and salinity in the water. When the general salt content in water exceeds 300-500 mg/L, the ratio of ions in water changes greatly, the proportion of HCO-3 in water decreases, and the proportion of Cl-, SO2-4 rises relatively high. Therefore, there is a high degree of salinization and salinity in water quality. In dry and rainless areas, the salt content in river water is as high as 1000-7000 mg/l. Therefore, with these salinized, highly mineralized waters, crops generally do not grow, they cannot grow crops, and they cannot even raise pure freshwater fish. Experience has shown that several freshwater fishes grown in China have poor growth when salinity is above 5 。. Such as carp larvae, the limit of adaptation to salinity is 6 ‰, then the growth of squid to adapt to the salinity of the high limit of 7 ‰ ‰ 10 ‰; carp larvae to adapt to the salinity of the limit of 5 ‰ ~ 6 ‰ 鲢 鲢 为 8 ‰~10 ‰. In theory, Cl- and SO2-4 ions are non-toxic, but in fact, in the absence of dissolved oxygen and soil-rich organic matter, sulfate can be reduced to sulphides by bacteria, and hydrogen sulfide, to fish, Poisonous. At the same time, practice and experience have also proved that under a certain alkalinity, the higher the PH value, the greater the toxicity, such as when the PH value of 10.1, the carp species in the 24-hour half-lethal concentration of 8.2 mg Equivalent/litre, and when the pH is 8.3, the concentration of 24-hour half-life salinity of the salmon species is 10.9 meq/l. Therefore, when the alkalinity is higher than 10 meq/l, the water quality must be modified to reduce the salinity before the fish can be used. Otherwise, at this high alkalinity, if the photosynthesis is strong, the PH value can be raised to 10, causing a large number of squid deaths. Under the synergistic effect of high salinity and high pH, ​​the toxicity of carbonate alkalinity is even greater. Therefore, carbonate-type semi-alkaline water has a strong poisoning effect on fish farming. In the sea salt and alkali area along the seashore, the water quality is affected by tides, and the water C l- is the most, which also has a strong poisoning effect on fish farming.
(II) Choosing salt ponds for fish farming The appropriate fish species should be adapted to local conditions. According to the specific conditions of saline and alkali degradation in different regions during the transformation of saline-alkali soil in different regions, the fish species that can be adapted to grow in this water area can be selected according to local conditions. Also consider the combination of market sales and good economic benefits. Generally during the initial period of reform, more widely salted fish species are used such as squid, barracuda, squid, tilapia, Macrobrachium rosenbergii, river crab, freshwater whitefish, leather beard bream, grass carp, and pupa, pupa, pupa. , squid, etc., with the process of row of alkali desalination, and then gradually expand the freshwater aquaculture freshwater fish species with good returns to improve economic efficiency.
(III) Renovation and Matching of Ecological Conditions for Fish Culture in Ponds in Saline and Alkaline Land
1. Deeply dig the pond and raise the saline-alkali area, which is characterized by drought, lack of water, serious leakage, large evaporation, high salinity, and high groundwater level. Therefore, in order to reduce leakage and reduce salinity, it is necessary to dig ponds and high-lift fields so that fresh water can be introduced into the pond, alkali pressure can be repeatedly reduced, alkali can be removed, and desalination can be carried out as soon as possible so as to facilitate the cultivation of crops and livestock and poultry on countertops. Kind of business, pond fish farming, the development of three-dimensional ecological agriculture. According to the principles of unified planning, reasonable layout, overall consideration and appropriate proportion, the ratio of the general pond and field is 1:1~2.5. Should vary according to the specific circumstances of each place. The ratio of ponds and fields in Shandong is generally about 1:2, and Kaifeng in Henan is about 1:2.5. The height of the table should be greater than the critical depth of underground diving, generally 1.5 to 2 meters. The slope ratio of Taitian is 1:2~2.5, and it is twisted around Taitian. It is 30 centimeters wide and 20 centimeters high, which is good for accumulating alkali and protecting pond slopes. It is usually about 1.5 meters from the underground, and 1.5~1.7 meters from Tanggu and Tianyang. The depth of the pond is 3~3.5 meters, and the depth of the fish is 2~2.5 meters. The area of ​​fish ponds ranges from 3 to 5 mu, and the area of ​​adult fish ponds is from 5 to 15 mu. The average area is about 10 mu. It is east-west and rectangular, with an aspect ratio of 5:3. The slope ratio is about 1:2.5.
2. The establishment of a reasonable drainage system in accordance with the planning, design, and strict implementation of the pond into the drainage separation, the main channel width of 10 to 12 meters, both ends of the river into the drainage gate to control the water level and direction. The ditch is high, and the ditch is lower than the bottom of the pool for easy access and drainage. At the same time, it is necessary to master digging ponds, lift surfaces, construct irrigation and drainage channels, electricity, water, and access roads, and carry out simultaneous inspections and production at the same time.
3, early open pond, rehabilitate the water according to the regional plan to implement water diversion, well drilling project, 50 acres of water with a well. Before the stocking of fish species, fresh water must be introduced repeatedly, and the salt alkalinity should be reduced after soaking. Generally, the water consumption per mu is 40-50 cubic meters. Due to the large salinity and high salinity, the discharged water cannot be introduced into fish farming.
4. After sufficient basal fertilizer is dug in the pond and rehabilitated, the organic fertilizer must be applied immediately so that the “birth pond†can be turned into a “cooked pond†as soon as possible. In general, 750-1000 kg of organic manure, such as cow dung and pig manure, per mu, and more than 1000-2000 kg, are better if there is green manure. However, alkali-tolerant plants such as Artemisia halodendron and Solanum can not be used as green manure By applying sufficient organic fertilizer, a layer of sludge can be deposited in the pond as soon as possible, and humus and other colloids in the sludge are embedded in the gaps in the soil. In this way, on the one hand it is possible to prevent the seepage effect of the sandy loam and, on the other hand, to reduce the pH of the pool water and the saline-alkaline soil and substantially isolate it from the saline-alkali soil. Therefore, this method is a key technical measure for newly reclaiming saline-alkali water quality in saline-alkaline ponds, and must be highly valued and carefully implemented.
5. The salt-tolerant, alkali-reducing green manure planted in Chipo and Chihchi is mainly planted with Sesbania, sorghum and so on. In this way, on the one hand, it is possible to prevent the seasonal return of alkali to the surface and the evaporation of groundwater. It can also loosen the soil and prevent the compaction of the soil structure, so as to desalinate and ripen the soil. On the other hand, these green crops can also be used as providing fish farming. The required green feed and green manure serve two purposes. Generally, other green feeds can be gradually cultivated after Ikebukuro and Chiba are grown for 2 to 3 years.
6. Injecting fresh water, draining water, removing silt, improving water quality in newly excavated ponds in saline-alkaline lands. In the first year of fish farming, the water quality is lean, and fresh water should be introduced frequently to drain the lower water. At the end of the year, dry old ponds should be drained. The old ponds that have been reared for 3 to 5 years have too thick silt deposits on the bottom of the pool, affecting the depth of the pool, the amount of fish loaded, and the effects of fish farming. Therefore, they should be removed. After removing excess silt, improving water quality conditions and increasing the space for fish farming, pond mud can be used as a good fertilizer for grass feed and crops on pond slopes, pond pools, and tabletops, and it can also help to change the saline-alkali soil structure. Reduce salinity.
After these general technical measures are taken, the salinity of soil can be gradually reduced. The salinity of pool water generally decreases from 4‰ in the first year to 2‰~2.5‰ in the first year and can be reduced to the second year. 1.5‰~2‰; the third year can be reduced to 1.3‰~1.5‰. The Huimin area in Shandong Province is a coastal area along the Yellow Sea with 1.2 million mu of saline-alkaline low-lying land with a groundwater level of 0.2-1 meter. The salt content in the soil is 2.69 ‰-7.43 ‰, and the alkalinity is 2-10 mg/eq. After two years of fish culture reform, the salt content decreased from 2.69‰ to 7.43‰ to 1‰ to 1.5‰, the alkalinity increased from 5~10 meq/d to 2~5 meq/l, and the PH value was generally From 7 to 8.6, other nutrient salts also meet the general requirements.
(d) Salt production ponds for fish farming in fish ponds
1. The type of ponds in the salt-alkaline ponds is modeled and divided from the production structure into four main types:
(1) The production structure pattern of the one-way cultured fish and fish stocks for simple fish farming. This model is divided into two forms: one is to stock only one species of fish in a pond, such as tilapia or Macrobrachium rosenbergii or river crab. Its method of fish farming is the same as that of general pond culture. This model is currently used less in production; the second is a one-stock or two-cultivated fish species, a variety of fish species with polyculture pond pure fish of a single fish breeding stock production structure model, U.S. experts also called the 80:20 fish farming model, with 80% of the main fish and 20% of other fish. This model is currently used more often.
(2) Fish-agricultural combination, raising-type dual stocking production structure model. This model is to raise fish in ponds (there is a single fish species to be stocked; there is also one farmed species, with multiple varieties and polycultures). Forages, vegetables and various kinds of economics are planted on Chipo, Ikoma, and countertops. Crops etc.
(3) Fish-Agriculture-Livestock and Poultry Combining, Raising-Cultivating-Cultivating ternary compound stocking production structure model, that is, based on the fish-agricultural combination and raising-species combined dual-stocking production model, further extending and increasing livestock husbandry Connotation, that is, fish farming in ponds, planting grasses and cash crops on pond slopes, pond pools, and countertops, raising livestock and poultry cattle, pigs, chickens, ducks, geese, etc As a fertilizer for planting grasses and cash crops on Chipo, Ikoma, and tabletops, ponds, ponds, and forages planted on bench surfaces, leaves, stalks, and stems of crops are used for fish farming, cattle raising, pig rearing, and raising. Goose's feedstuffs include livestock manure and grass stems and leaves, roots of crops, straw manure fish, grasses, vegetables and crops.
(4) Fish-Agriculture-Livestock and Poultry-Processing Combination, raising-species- raising-plus-combining multiple-element composite stocking production structure model. That is, on the basis of the previous model, it is further extended to increase the connotation of agricultural and sideline products processing. Processing here includes the processing of agricultural and sideline products grown on Chipo, Chiba, and countertops, such as bean curd and tofu, which are processed into soybean curd, mung bean by-products such as bean curd, and can be used for feeding fish and fertilizer.
2. Model production examples (A) Basic conditions (1) Pond conditions: Requirements of pond construction standardization, adult fish pond, rectangular, east-west direction, generally each pond area is 5 to 15 acres, an average of 10 acres, length to width ratio of 5:3 , slope ratio 1:2~3, generally 1:2.0~2.5. The water depth is 2 to 2.5 meters and the average is about 2 meters. The water source is introduced water and underground water, and some well water is supplemented.
(2) Machinery support: Generally, every 30 to 50 mu of water surface is equipped with 1 machine well and every 10 to 15 mu of water surface is equipped with an aerator or water pump. The requirements for water source, drainage, well, electricity, and road are basically complete. .
(3) Mesa: After leveling and applying basal fertilizer, the fertility is relatively sufficient. A 4-inch submersible pump is allocated for every 50 mu, which is convenient for watering and is suitable for the cultivation of various crops such as ryegrass, sudangrass, rapeseed, corn, peanut, and cotton.
(4) Livestock and Poultry: Fermentation ponds for cows, pigs, henhouses, and manures in ponds and countertops. Fermented feces can be fed into ponds and fish.
(b) Stocking mode (1) Fish-grass combination: The use of pond slopes, pond ponds, planting grasshoppers such as grasshoppers, Sudan grasses, etc., grasses and fishes, and ponds for herbivorous fishes.
1 Fish stocking mode: mainly grass carp, multi-species fish polyculture. Grass carp accounts for 50% to 70%, carp and carp accounts for 20% to 30%, carp and carp accounts for 10% to 20%.
2 Stocking densities: 800 to 1,500 tails per acre, 50 to 150 kg of fish, and 62.5 to 100 grams of tail weight.
3 feed feed: feed mainly forage, supplemented with other fine feed such as bran, not fertilize. When the artificially cultivated forage grass is insufficient, weeds are used as a supplement. The amount of feed is calculated as the weight of each 100 kg herbivorous fish. From April to May, 10 to 30 kg of fresh grass is fed daily, plus bran 3~ 5 kg; from June to September, only feed was fed, and the daily feeding amount was 30-60 kg; in October, 20-30 kg of fresh forage grass was added daily, and 2-7 kg of bran was added.
4 Test breeding results: The net production of fish was 611.67 kg (504.3-678.78 kg), including 383.54 kg (350.26-416.83 kg) of grass carp, accounting for 62.7% of the total output. Acres net profit of 1480 yuan, kilogram fish cost 2.92 yuan, input to output ratio of 1:1.84, feed ratio of forage grass 26.4 + bran 1.19.
(2) Fish-grain combination: Feeding fish with concentrate feed, mainly for cultivating edible fish.
1 Restocking mode: mainly tilapia, accounting for 70% to 80%; cockroaches and carp accounts for 10% to 15%; carp and other 10%.
2 Stocking densities: 2000 to 3000 tails per acre, of which tilapia size is 12.5-25 g/tail.
3 feeding feed: fed with compound feed, the ratio is: bean cake 15%, bran 40%, corn 40%, bean flour 5%.
4 Experimental fish rearing results: 678.75 kg (752.3-605.2 kg) of net fish production per mu, including 606.3 kg of tilapia (521.7-767.8 kg), accounting for 89% of the total production. The net profit of 2149.2 yuan, the cost of kilogramfish was 3.14 yuan, the input-output ratio was 1:1.82, and the feed coefficient was 2.17.
(3) Combination of fish and livestock: Fermentation of fish and fish by livestock and poultry excrement, and feeding of filter-feeding fish.
1 Restocking mode: filter-feeding fish (flea and squid) account for 50% to 70%; herbivorous fish (grass and cockroaches) account for 20% to 30%; omnivorous fish (flea, cockroach, tilapia) It accounts for 10%~20%.
2 stocking density: 600 ~ 800 acres of fish species, weight 60 ~ 90 kg, the average tail weight of 100 ~ 112.5 grams.
3 fertilizer feed: 1000-2000 kg of fertilizer per acre of water surface, of which: 30% for the base fertilizer, 70% for top dressing.
4 Breeding results: 357.3 kg (256.2-486.4 kg) of net fish production per mu, including 235.1 kg (210.5-346.7 kg) of carp and carp, accounting for 65.8% of total production. The profit per mu is 743.0 yuan, the cost of the kilogramfish is 2.06 yuan, and the input-output ratio is 1:1.9. Fertilizer coefficients are: wet cow dung 40, wet pig dung 25, wet chicken dung 10 (water depth 2 to 3 meters).
In the above three fish farming models, in addition to pond fish farming, crops such as wheat, corn, soybeans, vegetables and forage grasses, Sudan grass, and reeds can also be grown on the countertops, and livestock husbandry can also be cultivated, such as cow raising and raising. Pigs, broilers, etc.
For agriculture, animal husbandry and agriculture, the total output value per mu of water is 1,438 yuan and net profit is 744 yuan. The input-output ratio is 1:2.07. The yield per mu and the yield per mu were increased by 50.4% and 67.8%, respectively, when compared with that of pure fish farming; the input-output ratio increased from 1:1.21 to 1:1.80, and the production cost decreased by 37%.
After digging ponds and reducing alkali and alkali in Taitian, great achievements have been made in fishery and alkali treatment. From the results of soil composition analysis, after two years of renovation, organic matter increased from 0.563% to 1.053%, and total nitrogen increased from 0.0467% to 0.1154. %, the alkaline hydrolysis of nitrogen increased from 29.03 ppm to 35.05 ppm, the available phosphorus increased from 2.987 ppm to 8.97 ppm, and the available potassium increased from 28.93 ppm to 62.93 ppm. From the above-mentioned soil tests, we can see that, through comprehensive treatment, the production potential of low-alkali saline-alkali land reform is large, and after two years of reform, basically, it can be gradually improved, and both the pond slope and the pond can be fully utilized for planting.
V. Prevention of Fish Diseases In addition to the prevention and control of common fish diseases in freshwater fish culture, fish diseases in special conditions in fish culture in newly-digging fishponds in saline-alkali soils are mainly fish diseases related to high salinity alkalinity, such as trigeminoxin poisoning, Big Horn rickets and acute ammonia poisoning.
(a) Trigeosin poisoning
1. Symptoms: In the early stages of poisoning, diseased fish swim to the corners of the fish pond and react to external stimuli at the beginning. Later, they gradually become unresponsive. As the time for poisoning prolongs, the fish body becomes paralyzed after the pectoral fins, and the caudal, dorsal and pelvic fins cannot be placed. Although the pectoral fin can still be stroked, it cannot advance. Touch nothing. The lid, the mandible around the eyelids, the hyperemia of the body surface, the different sizes of the erythema, the difficulty in breathing, the intermittent struggle to breathe, and the loss of balance soon leads to death. Throughout the poisoning process, fish do not float, and they do not breathe on the surface of the water. Unlike simple oxygen deficiency, they cause death from breathing difficulties in paralysis. Some fish except for fin congestion, the body surface is generally not congested; some fish die open after death. If not rescued in time, it will cause the death of the whole pond fish.
2. Pathogen: Algae. Because trichophyton is a broad-salinity algae, suitable for growth and reproduction in saline-alkali waters, it grows well in bodies of water with salinity of 2 ‰ to 3 ,. The secretion of trigonous algae toxin can cause fish poisoning and death. In the body of water with a salt content of 2‰ to 5‰, the secretion of toxins is the strongest.
3. Prevention methods (1) Apply large-scale, fast-acting organic fertilizers such as chicken manure, human waste, etc. to the pond, and apply 500-800 kg per acre each time, together with the application of inorganic fertilizer, apply urea 5~8 per acre. Kilograms, or 4 to 5 kg of compound fertilizer, 5 to 7 kg of potassium dihydrogen phosphate, to increase the pond fertility, and promote the growth of other algae and zooplankton to inhibit, kill, and kill Trichophyton. Shandong Provincial Fisheries School applied 20ppm of NH4HCO3 or thiamin to treat trigeminal algae disease, with a cure rate of 90%.
(2) directly from the more fatty ponds to collect the surface of the pool of water 20 to 30 cm into the diseased fish ponds, once a day for 3 consecutive days.
(3) If there is a fresh water supply area, pool water in diseased fish ponds can be pumped out by more than half, timely inject new fresh water, and exceed the original water level by about 10 cm to maintain the balance of groundwater infiltration, and to dilute the content of saline and alkali in diseased ponds. , Destroying the proper salinity of Trigonella alkaloids, thus inhibiting and killing Trigonella alkaloids for therapeutic purposes.
2.鲤 鲤 鳋 鳋 ( ( disease (1) Symptoms: The diseased fish produce a large number of giant horns due to pupa tissue, stimulated by the worms, secrete a lot of mucus, severe tissue destruction, causing deformation, necrosis, loss of respiratory function, underwater Dissolved oxygen does not allow normal gas exchange through the helium, resulting in oxygen deprivation, severe floating heads, and even a large number of suffocation deaths. If the number of parasites is small and the illness is mild, there will normally be no acute deaths, but the body will be dark and the fish body will be lean, with slight floating heads or floating heads. At this time, if it can be treated promptly, the effect is better; if the carp suffers from severe carp, the first symptom is that a large number of clusters and floating heads occur in the hot season, similar to the state of hypoxia, especially in the windless weather, floating head The situation was even more serious. It lasted one week and started to die in large numbers. From June to August, when the water temperature is 25~26°C, it is the season when carp attacks. At the time of onset, the salinity in the water was 2‰~2.8‰, the PH value was 8~9, and the water hardness and sulfate content were both high. In the brackish water body of Tianjin, this worm is the main parasitic disease of squid, and the infection rate and infection intensity are extremely high, and the loss caused is also enormous.
(2) Pathogen: Giant Horned Owl. Giant horned owl is a unique parasitic crustacean on the scorpionfish and squid in the saltwater fish pond.
(3) Treatment: In the onset season, dipterex insects may be sprayed over the pond at a concentration of 0.25 to 0.27 ppm. The Xindi River and Yadian Reservoir in Tianjin spilled trichlorfon for several years in an epidemic season, effectively controlling the epidemic.
3. Acute ammonia poisoning (1) Cause: There are two problems in fish ponds newly excavated on the saline-alkali soil. First, there is a high salinity in the water, and the second is a thin water. Therefore, we must take measures: First, we must set alkali and reduce salinity; Second, we must apply fertilizer to fish. In general, more basal fertilizer and water are used to fish. This will not only modify saline land, but also adapt to fish farming. For general farmed fish, the general requirements are: ammonium - nitrogen 0.1 mg / l, nitrate - nitrogen 1 ~ 2 mg / l is appropriate. In the summer, salmonids allow nitrogen compounds to consist of ammonium-nitrogen 2 mg/l, nitrate-nitrogen 3 mg/l, and nitrite-nitrogen 0.1-0.2 mg/l; while in the winter, permissible The contents are: ammonium-nitrogen 1.5 mg/l, nitrate-nitrogen 3 mg/l, and nitrite-nitrogen 0.1 mg/l.
Therefore, when ammonia-nitrogen exceeds the standard, acute ammonia poisoning may occur. The safe concentration of ammonia is 0.05 milliequivalents per liter for salmonids, 0.09 milliequivalents per liter for salmon fry, and 0.054 to 0.099 milliequivalents per liter for grass carp.
2. Illness: Sick fish swim slowly or stop. Responsive, not afraid of people. The tail of trout trembles and there is obvious congestion on the body surface. Ammonia directly causes lysis of epithelial cells and hemolymph, reducing the oxygen carrying capacity of blood and reducing the respiratory function.
3. Prevention and control methods (1) To closely monitor the water quality, comprehensive consideration should be given to factors such as salinity, alkalinity, pH, and composition of plankton.
(2) If any signs are found, one must reduce the topdressing fertilizer as appropriate, and secondly, replace the pool water.
Gauze Bandage,Triangular Bandage,Adhesive Plaster
Boda Medical Products Co., Ltd. , http://www.nbmedicals.com