Is the fathead fish a marine fish or a freshwater fish?

The fathead fish is a freshwater fish.

The fat-headed fish (scientific name: Aristichthys nobilis) is also called silver carp, bighead carp, baotou fish, big-headed fish, black silver carp, hemp carp, and also called male fish. It is a type of freshwater fish. Known as the "scavenger in the water", it is one of the four major fish species in China. It looks like a silver carp, with a flat side body. The head is larger and wider, and the mouth is also very wide and slightly upturned. The eye position is relatively low. Bighead carp grows in freshwater lakes, rivers, reservoirs, and ponds. Mostly distributed in the middle and upper layers of waters. It is a fish unique to China. It is widely distributed in China. It is one of the main objects for pond culture and reservoir fishery, and has high economic value. It is edible and has the effects on the human body of improving IQ, enhancing memory, supplementing nutrition, and delaying aging.

1. Habitat environment

Bighead carp grows in freshwater lakes, rivers, reservoirs, and ponds. Mostly distributed in the middle and upper layers of freshwater areas. It is a warm-water fish, and the water temperature suitable for growth is 25-30°C, and it can adapt to more fertile water environments. Young fish and immature individuals generally grow in lakes and ancillary water bodies along rivers.

2. Living habits

Bighead carp are docile and do not like to jump.

Food: Filter feeder, mainly eats rotifers, cladocerans, copepods (such as water fleas) and other zooplankton, and also eats some phytoplankton (such as diatoms and cyanobacteria) and artificial feed . From fry to adult stage, they mainly eat zooplankton and also eat phytoplankton. They are typical plankton-eating fish.

3. Distribution range

Unique to China. It is distributed in a wide range of water areas and is found in almost all freshwater basins from south to north in China.

IV. Breeding technology

1. Breeding model

The traditional ratio of silver carp and bighead carp is 3:1, that is, 3 silver carp and 1 bighead carp. They are 75% and 25% respectively. According to production practice, in the stocking structure of silver carp and bighead carp, the proportion of bighead carp is less than 20% or the proportion of silver carp is greater than 80%. The growth rate of bighead carp is faster. When the stocking proportion of silver carp is between 20% and 80% will inhibit the growth rate of bighead carp. When bighead carp is used as the main fish, silver carp should be stocked with a small amount or not. ?

2. Seed stocking

In the past, the stocking size of bighead carp in lakes and reservoirs was generally about 13.2cm large-sized fingerlings. Under modern technical conditions, 0.15-0.5kg is required. /Tail or even 1.0kg large size fish.

(1) Stocking time: It should be carried out in winter or early spring when the water temperature is 5 to 10°C. At this time, it is conducive to high-density transportation of fish species, which can reduce casualties during transportation; the activity abilities of fish species and ferocious fish are weakened, and the harm of ferocious fish to stocked fish species is also relatively reduced.

(2) Stocking location: A fertile reservoir bay with shallow water, shelter from the wind and facing the sun should be selected upstream of the reservoir. In this way, away from the spillway and flood discharge tunnel downstream of the reservoir, the escape opportunities of stocked fish species can be reduced, the adaptation time to the large water surface environment can be shortened, growth can be accelerated, and the survival rate can be improved.

(3) Stocking weather: You should choose to stock on a windy and sunny day, not on a windy, snowy or icy day.

(4) Quarantine and disinfection: Fish disease quarantine and fish fingerling disinfection must be carried out before stocking and entering the warehouse. It is strictly prohibited to stock fish species with infectious diseases into the warehouse.

(5) Careful operation: After long-distance transportation of fish species to the reservoir, the reservoir water should be slowly added to the fish container until the water temperature in the container is not much different from the reservoir water temperature. , and then slowly put the fish species into the warehouse. After the fish species are placed in the reservoir, the stocking personnel should stand beside the reservoir or on the boat, use paddles to gently stir the reservoir water, and slowly drive the fish species to swim to the large surface of the water. ?

3. Water quality control

Regulating water quality has three major functions:

The first is to improve water quality.

After the beneficial bacteria in the microecological preparations enter the water body, they exert their oxidation, ammoniation, denitrification, phosphorus decomposition, sulfurization, nitrogen fixation, etc. functions, and quickly decompose organic matter such as excrement, residual feed, animal remains, etc. of farmed animals, effectively reducing the pollution in the water body. Ammonia nitrogen and nitrite concentrations;

The second is that the salts after the decomposition of organic matter provide a good ecological environment for the growth and reproduction of single-celled algae, and provide nutrients for the growth and reproduction of single-celled algae, and the photosynthesis of single-celled algae It also provides dissolved oxygen for the oxidative decomposition of organic matter and the respiration of cultured organisms, forming a virtuous ecological cycle, maintaining and creating good water quality conditions, maintaining water quality stability for a long time, achieving water and fertilizer stability, and thus conducive to the healthy growth of cultured objects. . At the same time, it can also increase the number of zooplankton and beneficial algae in the culture water body, expand the source of feed, and reduce production costs.

The third is disease prevention. The beneficial bacteria of microecological preparations are released into the aquaculture water, which not only competes to exclude pathogenic bacteria, maintains the ecological balance of the microecological flora in the water, and prevents aquatic organisms from being attacked by pathogenic bacteria, but can also produce antibacterial substances and a variety of Immune promoting factors activate the body's immune system, strengthen the body's counterattack response, enhance the ability to resist disease and improve survival rate. ?

4. Food use

(1) Analysis of feeding habits

In the past, under low-level breeding conditions in the natural environment, bighead carp mainly fed on zooplankton. Food. According to research on the feeding habits of bighead carp, a large amount of organic fertilizer must be provided to cultivate large phytoplankton, zooplankton and humus. When the water body lacks large plankton, the humus in the organic fertilizer is used as the main food for silver carp. Under fertile water conditions, plankton are mainly linear diatoms, dinoflagellates, cryptophytes, large rotifers, cladocerans, copepods and other species with an individual size larger than 50 microns, which are exactly the filter feeding targets of big carp. ?

(2) Fertilizer use

Principle: By putting organic fertilizers, inorganic fertilizers and biological compound fertilizers into large water bodies such as reservoirs and lakes, the nitrogen and phosphorus in the water body can be increased. and other main nutrients and other elements, improve the primary productivity of the water body and increase the yield of bighead carp.

The earliest fertilizers used in fisheries were primitive organic fertilizers, such as manure and compost, and later inorganic fertilizers were used. Original organic fertilizer has comprehensive nutrition, low active ingredients, and slow fertilizer effect, which limits fish production. Inorganic fertilizers have high content of active ingredients, short fertilizer effects, and single ingredients. They mainly cultivate small green algae and cyanobacteria, which are beneficial to the growth of silver carp, but are not ideal for bighead carp farming. Modern bio-organic fertilizers for fisheries, which are made by decomposing traditional organic fertilizers through modern biotechnology and mixing them with inorganic fertilizers in an appropriate amount, contain a large amount of macroelements such as nitrogen, phosphorus, and carbon, as well as balanced trace elements, a large amount of humus, and peptides. species, beneficial bacteria, fertilizer efficiency enhancers, etc. It has the effect of fertilizing water, changing water, and controlling water. It is also particularly suitable for cultivating macroalgae, rotifers, cladocerans, copepods and other plankton that bighead carp likes to eat, providing a material basis for high-yield cultivation of bighead carp. ?

5. Disease prevention and control

(1) Disease prevention and control

Fish disease prevention and control adheres to the policy of "prevention first, combining prevention and treatment". Fish diseases are generally prone to occur in "Barley Yellow, White Dew Heart". One is when the water temperature gradually rises, and the other is when the water temperature gradually drops. These two seasons are the peak seasons for the prevalence of fish diseases, so prevention should be taken in advance. To prevent diseases, we should kill insects first and then sterilize them. Use visual inspection or microscopy to diagnose fish diseases and prescribe appropriate medicines.

A. Parasitic diseases: Insecticides should be killed once every year from April to May. Water bodies that use a large amount of organic fertilizers should be killed once from July to August. Common parasitic diseases in large water bodies are:

a. Chinese worm disease: Its symptoms are that eggs or parasites are parasitic on the gills of fish. When there is a small amount of parasitism, there are no obvious symptoms. When there is a large amount of parasitism, the mucus on the gills of the diseased fish increases, and the ends of the gill filaments are swollen, edematous, pale, and pale. They have difficulty breathing and are restless, spinning or swimming wildly on the surface of the water body, with their tail fins often exposed out of the water. This is commonly known as "tail lift disease", and they eventually lose weight and die of suffocation. Mainly used avermectin or pyrethroid drugs for prevention and treatment.

b. Anchorhead worm disease: Its symptoms are that large worms can be seen on the surface of the diseased fish, and the parasitic area is congested and red, irritable and restless, with a loss of appetite, and then the fish becomes emaciated and dies. Mainly used avermectin or pyrethroid drugs for prevention and treatment.

B. Fulminant hemorrhagic disease: Symptoms are exophthalmos and congestion; the body surface is congested and red. There are two types:

a. Primary hemorrhagic disease: only sterilization is required.

b. Secondary hemorrhagic disease: First, the bottom fish dies, and the physical and chemical indicators of the lower layer seriously exceed the standard, and then large areas of fish die. Kill insects first, then sterilize and adjust water according to the situation.