How to Clear Wild Trash Fish from Fish Ponds? Four Methods to Solve It Easily

When filling, changing water, and feeding aquatic plants in intensive ponds, wild trash fish or their eggs such as sharpbelly, topmouth gudgeon, crucian carp, @#@237@#@, and grass shrimp inevitably get mixed in. These wild trash fish not only have strong food-grabbing ability, a large feeding volume, and low economic value, but also reproduce quickly. In addition, carnivorous predatory fish such as snakehead and catfish can also swallow cultured fry. Therefore, various measures must be taken in aquaculture management to remove wild trash fish.

1. Kill the wild trash fish in the pond in advance. Before stocking fry, drain the pond water, let the pond bottom freeze and sun-dry for a period of time, then add 20-30 cm of pond water, and use quicklime and camellia seed cake respectively for disinfection. Dosage: quicklime 1500-2250 kg/hectare, camellia seed cake 750 kg/hectare. Method of use: after slaking quicklime into slurry, splash it over the whole pond, and after one day use an iron rake to turn the bottom mud; soak the camellia seed cake for one full day and night, then splash the residue and liquid together over the whole pond, check the death of wild trash fish after 3 hours, and remove the dead fish. If any surviving wild trash fish are found, another chemical treatment is needed.

2. Cut off the sources of wild trash fish. There are three main ways wild trash fish enter crab ponds: first, when adding or changing water; second, @#@235@#@ when transplanting aquatic plants such as water peanut that crabs attach to on the water surface, wild trash fish eggs are brought in; third, they are brought in when feeding aquatic plants. Installing a fine-mesh net bag made of 2 mm mesh polyethylene, gauze, or similar material at the water inlet can effectively prevent wild trash fish, eggs, and aquatic insects from entering the pond; aquatic plants that are transplanted or fed, such as water peanut, can be sun-dried for 1-2 days, and aquatic plants can be sun-dried for 1-2 hours, or soaked for 2 hours in chemicals (5 mg/L copper sulfate solution, 30 mg/L camellia seed cake soaking liquid, etc.).

3. Trap wild trash fish and set fish nests. First, use fine-mesh netting to make a 3-4 sq m lift net, set it near the water inlet, place bait that wild trash fish like to eat on it, lift it once about every half hour, and remove the wild trash fish; second, place ground cages in the crab pond and collect them 1-2 times a day. It is worth noting that the cage tail opening should be opened and raised above the water surface so that crab juveniles that accidentally enter the cage can crawl out; third, use a dip net to catch wild trash fish at the bottom of water peanut clusters; fourth, use hooks or forks to catch adult snakehead in the pond, and when eggs or young fish are found during their breeding season, scoop them out with a net. Fifth, during the breeding season of wild trash fish, use tree roots, palm fiber, aquatic plants, etc. to set fish nests in the pond so that wild trash fish lay eggs on the nests, and promptly remove and take away the nests.

4. Stock carnivorous fish to eat the wild trash fish. Practice has proved that biological removal of wild trash fish is also quite effective. Adult fish ponds or two-year-old fingerling ponds can polyculture carnivorous fish such as mandarin fish, @#@243@#@ fish, and large-mouth catfish, but the polyculture quantity must not be too large, the size should be less than 2/3 of the domestic fish, they must be counted and recorded when put in, and the pond must be drained and harvested at the end of the year so that all carnivorous fish can be caught, so as not to harm the domestic fish. In crab ponds, stock fingerlings of carnivorous fish that do not pose a threat to crabs, such as mandarin fish, yellow catfish, and topmouth culter. According to the number of wild trash fish in the crab pond, generally in April to June, stock per hectare 150-225 mandarin fish over 5 cm, or 4500 yellow catfish about 3 cm, or 300 topmouth culter fingerlings 10-15 cm in body length. This can not only remove wild trash fish from the crab pond, but also harvest a certain amount of valuable aquatic products, increasing breeding benefits by 10%-20%.