1. Feeding habits of fish
Carnivorous: such as catfish and mandarin fish;
Omnivorous: carp, crucian carp, tilapia, etc.
Herbivore: grass carp;
Filter feeding: silver carp and bighead carp.
Reasonable collocation should be made according to the different feeding habits of fish in pond culture production.
Adapt to water temperature
Fish can be divided into tropical fish, warm water fish and cold water fish according to their adaptability to different water temperatures.
Tropical fish: Generally, the low adaptive water temperature is around 10℃. For example, tilapia begins to die when the water temperature drops to 12℃, and the maximum adaptive temperature can reach 40℃, the adaptive water temperature is 16~40℃, and the optimal adaptive temperature is 28~32℃.
Warm-water fish: most of them adapt to the water temperature of 0~32℃, such as carp. When the water temperature reaches 10℃, they begin to feed, and the optimum growth water temperature is 24~30℃.
Cold water fish: the upper limit of adapting to water temperature is about 20℃. If the adaptive water temperature is 4~20℃, the optimal growth water temperature is 12~ 18℃. If the water temperature exceeds 24℃, it is easy to die.
Second, pond culture and regulation
1.ph value
The optimum PH value of fish is 7.0~8.5, and all fish die when the PH value is < 4 or > 10.6.
When the PH value is less than 7, the PH value in fish blood decreases, which reduces the oxygen partial pressure in blood and the oxygen carrying capacity of hemoglobin, which can directly destroy gill tissue cells and epidermis, leading to the decline of fish physique and disease resistance. At the same time, low PH will affect the growth and reproduction of bacteria and algae in water and reduce the natural feed for fish.
When the PH value in the water is greater than 7, it will affect the balance of NH3-NH+4 ions in the water, increase the concentration of toxic nonionic ammonia, cause harm to fish, and at the same time make fish secrete a lot of mucus, which will affect their breathing.
Adjustment: When the PH value in the water is less than 7, it can be adjusted with quicklime; Otherwise, when the PH value is higher than 9, it is difficult to adjust and the cost is high, so it is not recommended.
2. Dissolved oxygen
Effect of dissolve oxygen on fish
Fish breathe dissolved oxygen in water through gills. When the dissolved oxygen in water is less than 4 mg/L, the food loss of fish is 13%. When it is lower than 3 mg/L, the food consumption will be reduced by 36%; When it is lower than 2mg/L, the food consumption will be reduced by 54%; When it is lower than 1 mg/L, food is stopped, and the phenomenon of floating head appears, and in severe cases, it appears generalized.
2) Source of dissolved oxygen
There are two ways to dissolve oxygen in water. One is the photosynthesis of phytoplankton and aquatic plants in water; Second, oxygen in the air diffuses and dissolves in water. In sunny days, more than 95% of dissolved oxygen in pond water comes from photosynthesis of phytoplankton, so it is extremely important to cultivate phytoplankton in water.
3) Oxygen consumption in water body
Oxygen consumption in water can be divided into biological oxygen consumption and chemical oxygen consumption. Biological oxygen consumption refers to the oxygen consumption of fish, zooplankton and other animals, phytoplankton and aquatic plants in the water when there is no light at night.
Chemical nutrient consumption refers to the oxygen consumption of organic matter in water by oxidation and decomposition under the action of bacteria, which often accounts for a considerable proportion, generally reaching more than 72% of the oxygen consumption.
4) Oxygen increasing measures
A, cultivate a certain number of high-quality phytoplankton. The phytoplankton can be cultivated to 20 mg/L ~ 100 mg/L through measures such as fertilization and water regulation, so as to keep the phytoplankton tender but not old, and keep the phytoplankton in the water in a high oxygen-producing state.
B, reduce the chemical oxygen consumption
(1) During the fishing leisure period, remove the sediment with peculiar smell at the bottom of the pond.
② Appropriate scientific feeding to reduce the deposition of excess feed.
③ At noon on a sunny day, the aerator is often turned on to bring the upper water with high oxygen content into the bottom, so that the organic matter in the sediment can be rapidly decomposed, thus reducing the oxygen consumption at night.
C, reduce unnecessary biological oxygen consumption, kill wild fish and shrimp, and kill too many zooplankton.
3. Amino nitrogen
Ammonia nitrogen, including ionic ammonia (NH4+) and nonionic ammonia (NH3), is the main metabolite of aquatic animals such as fish, and also the product of oxidative decomposition of organic matter. Ionic ammonia provides nitrogen for the growth and reproduction of phytoplankton, and phytoplankton in water preferentially use the nitrogen of ionic ammonia. Molecular ammonia is toxic to fish, and its toxicity increases with the increase of PH value. When the PH value is less than 6, they all exist in the form of ionic ammonia, and when the PH value is greater than 1 1, they all exist in the form of molecular ammonia.
? NH3+H2ONH+4+OH-
NH3 will damage the gill tissue of fish, reduce the ability to absorb and transport oxygen, and prevent ammonia in fish from being excreted, which will cause fish to reduce their food intake or even stop eating, and affect their osmosis. The concentration of nonionic ammonia is less than 0.05 mg/L and the total ammonia is less than 2 mg/L for aquaculture water.
The methods to control ammonia nitrogen exceeding the standard are: ① changing water; ?
? (2) sprinkle 20-50kg zeolite powder per mu;
③ Sprinkle 2~ 10 mg/L sodium borate (borax) on the whole pool;
④ Sprinkle 20 mg/L quicklime on the whole pool;
⑤ Spraying microbial agents such as photosynthetic bacteria or nitrifying bacteria in the whole pond to purify the pond water;
⑥ Open the aerator to explode at noon on a sunny day.
4. nitrite?
Nitrite is an intermediate product of organic matter decomposition, which can be further oxidized into nitrate when dissolved oxygen is sufficient. When dissolved oxygen is insufficient, nitrite is produced, which can quickly destroy gill tissue and make gill tissue cells expand and proliferate. Nitrite is absorbed into the blood of fish, and reacts with hemoglobin (HB) to produce methemoglobin (MHB), which leads to low food intake rate, lack of oxygen in the body, weak constitution, slow growth rate and easy infection with pathogenic bacteria. The nitrite content in aquaculture water shall not exceed 0.1mg/L.
Control methods: ① The same as the measures for controlling ammonia nitrogen toxicity;
(2) Sprinkle salt on the whole pond to make the concentration of pond water reach 20 mg/L. ..
2. Feeding techniques
Feed feeding should follow the principle of "quality, quantity, fixed point and timing".
Quality assurance: use high-quality complete feed, and choose different feed varieties according to different fish species and different growth periods. Malnourished feed and overnourished feed cannot be used. Low nutrition can't make fish reach the best growth rate; Overnutrition causes waste of nutrition and may also cause nutritional metabolic diseases.
Appropriate amount: the daily feeding amount is generally expressed as a percentage of fish weight, which is called feeding rate. The determination of feeding rate is closely related to fish species, fish size, water temperature, water quality and dissolved oxygen.
Average weight (grams)
Tuantou
carp
Grass carp; Buji fish
25
3.5
4.0
4.0
4.5
4.5
50
3.2
3.5
3.2
4.0
3.7
75
3.0
3.2
3.2
3.6
3.4
100
2.8
3.0
3.0
3.3
3.2
150
2.6
2.5
2.8
3. 1
3.0
200
2.3
2.5
2.5
2.9
2.8
250
2. 1
2.2
2.2
2.6
2.5
300
1.9
2.0
2.0
2.4
2.3
celebrity
1.6
1.6
1.6
2. 1
2.0
500
1.4
1.4
1.7
1.7
600
1.2
1.2
1.4
1.4
Note: 1, applicable water temperature is 24 ~ 29℃;
2. Water temperature
3. When the water temperature is 5~ 19℃, the feeding rate is 60%;
4. When the water temperature is 20~23℃, the feeding rate is 80%;
5. When the water temperature is 30~32℃, the feeding rate is 80%;
6. water temperature >; At 33℃, generally do not eat.
In the actual aquaculture production, we should master it flexibly according to the environmental conditions of the water body at that time, especially the water temperature and dissolved oxygen in the water. When 80% of the fish eat and leave the bait table, we will stop feeding.
Fixed point: that is, the feeding point is a fixed feeding table. Set a bait table every 30~50 mu.
Timing: regular quantitative and regular feeding. Generally, carnivorous fish have stomachs, which can store food. Generally, it can be fed 2~3 times a day. Cyprinidae fish have no stomach and their food metabolism is fast. Generally, it is advisable to feed it 4~5 times a day.
Feeding mode: there are two kinds of compound feed feeding: manual feeding and mechanical feeding. When feeding artificially, because of its small feeding area, fish schools often compete for food, and because of the difference of individual size, the individual size of fish schools is divided. The mechanical feeding area is large and uniform. No matter which feeding method is adopted, it is necessary to feed slowly at both ends and quickly in the middle, that is, to start feeding slowly and speed up feeding when most fish grab food on stage; When most people are full, they should be fed slowly, and the feeding time is generally not less than 30 minutes, depending on the specific situation at that time.
(3) Feeding management
1, reasonable stocking mode
In pond culture, the compound feed is mainly edible fish. Cooperate with filter-feeding fish, make full use of water and biological bait in water, and also adjust water quality. The collocation ratio is: prey fish accounts for 80% and filter fish accounts for 20%. The ratio of silver carp to bighead carp is generally 4 ~ 5: 1.
It is worth noting that grass carp is more aggressive in grabbing food, while crucian carp is less courageous. Generally, carp or crucian carp is the main pond without grass carp, and crucian carp is the main pond without grass carp and carp The main fish eaters are domesticated before throwing silver carp and bighead carp.
The input amount should depend on pond conditions, management conditions, expected output, specifications and input specifications.
2. Actively prevent diseases
Fish live in water, not as easy to be found as land animals, and it is difficult to give medicine. In daily production, drugs are only used for external use-splashing and taking orally-and added to feed. The fish is seriously ill. If it doesn't eat, it can't be treated by internal medicine. Therefore, it is extremely important to prevent diseases in production, prevention is more important than treatment, and prevention and treatment should be combined.
1) Clean water tank disinfection
Answer: Cleaning the pond: When the pond is dry in winter, clear the thick silt in the pond, dry the pond in the sun, clean the pond with quicklime, bleaching powder and other drugs to kill insects, eggs and pathogenic organisms in the pond.
B: disinfection: it is divided into water disinfection and fish disinfection.
Disinfection of fish: Fish enter Tang Qian for medicinal bath disinfection.
In the process of breeding, medicine baskets (bags) can be hung around the food regularly to make the local water around the food field reach a certain medicine concentration, and fish can be disinfected by medicine bath when they enter the food field.
Disinfection of water body: that is, the use of external drugs to prevent bacterial and parasitic diseases of fish. Commonly used drugs: quicklime 20mg/L, bleaching powder 1mg/L, hydantoin 0.2 ~ 0.3mg/L, mixture of copper sulfate and ferrous sulfate.
(5:2)0.7 mg/L, trichlorfon 0.3~0.5 mg/L, etc.
2) Use microecological agents regularly.
External disinfection cannot be used for 5-7 days before and after the use of microecological preparations.
Things. probiotics
Sludge organic matter is rapidly oxidized and decomposed, and the reproduction of harmful bacteria is inhibited.
3) scientific use of aerator
Start the aerator 1-2 hours at noon on sunny days, aerate the bottom water containing harmful substances at the bottom of the pond, bring the oxygen-rich water at the top of the pond to the bottom, accelerate the oxidative decomposition of organic substances at the bottom, reduce the contents of harmful substances such as ammonia nitrogen and nitrite in the water, and reduce the chemical oxygen consumption at the bottom at night.
Step 3 patrol the pond
Patrol the pond in the morning, at noon and at night, observe the feeding and activities of fish, and judge the health status of fish. Observe the changes of water body, water quality and water color.
Step 4 apply fertilizer
Organic fertilizer is the main base fertilizer, and chemical fertilizer is the main topdressing. Top dressing once every half a month or so. Urea is used for nitrogen fertilizer and calcium superphosphate is used for phosphate fertilizer, with the dosage of 5 ~ 10kg/ mu each time. After dissolution, it is scattered throughout the pond. It is not easy to lack nitrogen fertilizer in ponds where herbivorous fish are fed with granular feed, so phosphate fertilizer is mainly used as topdressing to supplement the shortage of phosphorus in water.
When using phosphate fertilizer, we should pay attention to: fully dissolve it in sunny morning before spreading it, so that phytoplankton can be used in time. At the same time, it should be avoided before and after using quicklime and when the pool water is turbid, so as not to reduce the fertilizer efficiency.
The purpose of fertilization is to provide sufficient nutrition for phytoplankton and promote its growth and reproduction. Adjust the water quality, keep "fat, tender, lively and refreshing", provide bait for silver carp, and maintain the high oxygen production capacity of pond water.
(2) Preliminary judgment of fish diseases
1, sudden mass death-bubble disease, poisoning, flood.
2, gradual death-according to the symptoms, with the help of a microscope.
(3) Several common diseases
1, bacterial hemorrhagic disease of freshwater fish
Also known as bacterial septicemia and fulminant hemorrhagic diseases.
Pathogen: ① Yersinia Luke, which is suitable for reproduction at water temperature 10 ~ 20℃; ② Aeromonas hydrophila; ③ Vibrio fluvialis is a biological species, and the latter two species are suitable for breeding at water temperature of 20~30℃, so the epidemic season of the disease is long, and the pathogen can survive for two months in water and more than one year in sediments.
Symptoms: At the beginning of the disease, the fish's mouth, jaw, gill cover, eye socket, fins and both sides are slightly congested. In severe cases, there is congestion around the orbit, exophthalmos, abdominal swelling, anal swelling and intestinal congestion.
Prevention: 1, thoroughly clean the pond, remove excessive silt, and clean the pond with quicklime and bleaching powder;
2. Spray 20mg/L of quicklime,1~ 2mg/L of bleaching powder or 0.3mg/L of dibromohydantoin to the whole pond every half month;
Treatment: On the first day, a 5: 2 mixture of 0.7 mg/L copper sulfate and ferrous sulfate was sprinkled on the whole pond;
? The next day, the whole pool was sprayed with 0.4 mg/L of strong chlorine essence or 0.3 mg/L of hydantoin. At the same time, fish blood Kangning mixture (200g/ 100kg) was taken orally for five to seven days.
2, gill rot
Rotten gill disease can be divided into bacterial infection and secondary bacterial infection caused by parasites. In the range of 15~30, the incidence rate increased with the increase of water temperature.
Prevention and control: on the first day, use pesticides to kill insects;
The next day, the whole pond was sprayed with 0.2~0.3 mg/L of chlorine dioxide or 0.3 mg/L of dibromohydantoin, and enrofloxacin was taken orally at the same time, and 20~50 mg was added to each kilogram of fish for 5~7 days. In severe cases, it should be disinfected externally and sprinkled again every other day.
3. Intestinal diseases
The water temperature is above 65438 08℃, and the epidemic peak can be formed at 25~30℃.
Symptoms: the anus is red and swollen, the abdomen is swollen, yellow liquid is discharged by gently pressing the anus, and there is water in the abdomen. After incision, the intestinal wall is congested, there is pus in the intestine, there is no food in the intestine, and the elasticity of the intestinal wall is poor.
Prevention and control: external use: 1, quicklime concentration of 20 mg/L overflows the whole pool; ?
? 2. The concentration of chlorine dioxide is 0.3 mg/L, and the whole pool overflows;
? 3. The concentration of dibromohydantoin is 0.3 mg/L, and the whole pool overflows.
Internal medicine: 1, florfenicol 30~50 mg/l fish weight, doubled on the first day, for 4~6 days;
? 2, enrofloxacin 20~30 mg/L fish weight, for 5~7 days.
4, toe disease
Dactylogyrus hooks parasitic gill tissue with its anchor hook and small hook on the edge, and constantly moves like an inchworm on the gill, destroying the epidermal cells of gill filaments. Stimulate gill filament cells to secrete too much mucus, hinder fish breathing, and make fish anemia. Sick fish have difficulty breathing and slow swimming, and often float on the water in groups, with swollen gills and difficult to close gills.
Control: 1. Spraying crystal trichlorfon 0.2 mg/L in the whole pond;
2. Spraying 0.2 mg/L mixture of crystal trichlorfon and sodium carbonate (1: 0.6) in the whole pond;
3. Spraying deltamethrin or abamectin insecticide in the whole pool;
4. Ivermectin mixed oral: 50 mg/kg fish. Days, and spray 0.4 ~ 2mg/L in the whole pool for external use.
5. Myxosporiasis
There are thousands of species of sporozoites, which are parasitic in different organs and tissues of fish, such as body surface, gill, cranial cavity, internal organs and so on. Sporozoa is covered with chitin shell, so it is difficult to kill. When parasitic on the body surface and gills, many rice-sized cysts can be seen with the naked eye.
Prevention and control: 1. Thoroughly clean the pond, remove silt, and clean the pond with lime nitrogen (calcium cyanamide) at the dosage of 100 kg per mu or the concentration of 150 mg/L to kill eggs and spores;
2. Take levamisole orally, 4~8 mg/kg fish every day for 2~3 days;
3. Spray crystal trichlorfon 1mg/L in the whole pond. At the same time, chlorpheniramine hydrochloride and sulfadiazine 100 mg were taken orally per kilogram of fish, and halved the next day for 4 days; Or mixed with cyclophosphamide hydrochloride orally, 400 mg/kg fish every day for 3~6 days.
4. The main components of oral Chinese medicine.