6 common situations that affect fish feeding

In intensive fishery production, the management of feed feeding is one of the main links in the entire production management. During the feed feeding process, the phenomenon of reduced feed intake by fish often occurs. Based on different situations in production, the author describes the reasons for reduced feed intake by farmed fish as follows:

The first situation: fish are currently diseased, causing reduced feed intake by fish. For example, when diseases such as crucian carp internal sporidiosis, grass carp three diseases, channel catfish hemorrhage disease, and enteritis occur, the feed intake of fish is significantly reduced. When grass carp fingerlings and crucian carp have a large number of Trichodina parasites, the phenomenon of spinning and frenzied swimming in front of the feeding table will occur, affecting feeding and reducing feed intake.

This situation occurs in the early stage of disease onset. Once reduced feed intake appears, attention must be paid to it. The fish body should be examined immediately, and according to the specific situation, diseases should be prevented and treated. After the fish body recovers to health, feed intake can return to normal.

The second situation: poor water quality causes reduced feed intake by fish. When dissolved oxygen in the water body is insufficient, water quality is aging, ammonia nitrogen, nitrite nitrogen, and hydrogen sulfide seriously exceed standards, and the water body is polluted by high copper, all of these will cause a decline in fish feed intake.

If fish feed poorly in the morning and feed well at noon and in the evening, the main reasons are insufficient dissolved oxygen in the water body, aging water quality, or excessive ammonia nitrogen, nitrite nitrogen, and hydrogen sulfide.

In response to this situation, the main approach is water quality regulation. As the old saying goes, to raise a pond of fish well, first raise a pond of water well. Water quality regulation is an important part of scientific aquaculture. During the breeding process, attention should be paid to maintaining the fertility, liveliness, tenderness, and freshness of the aquaculture water body. Fertile: transparency of 30 cm to 40 cm, tender green color, appropriate quantities of plankton and zooplankton, and the water body can provide relatively abundant natural bait for fish. Lively: good algal phase, regular daily and periodic changes in transparency and pH, and regular changes in concentrations of ammonia nitrogen, calcium, phosphorus, etc. Tender: tender green water color, many new phytoplankton, many beneficial bacteria, conducive to fish growth. Fresh: water quality has no oily or greasy feel, and few dead algae. The main regulation methods are to turn on the aerator promptly every day, frequently add new water, raise the water level, advocate the use of beneficial biological preparations, and improve the substrate and water quality. During high-temperature periods, frequently replace part of the old water. It is best to use photosynthetic bacteria or EM bacteria once every 15 days.

The third situation: due to the massive reproduction of Prymnesium parvum in the water, large amounts of fish toxins, cytotoxins, hemolysins, neurotoxins, etc. are produced. The algal toxins are activated and reach a certain concentration, causing reduced feed intake by fish.

When the total ammonia content in the water exceeds 0.25 mg/L, Prymnesium parvum cannot become the dominant species. Therefore, regularly applying ammonia salt fertilizers, urea, nitrogen-phosphorus compound fertilizers, and organic fertilizers to the pond in small amounts multiple times, so that total ammonia is stabilized at 0.25 mg/L to 1 mg/L, can achieve a preventive effect. In the early stage of diseased fish ponds, use 100 kg of clay soil per mu of water surface, add water to make mud slurry, first splash it in the dense diseased fish areas at the four corners of the pond, and then splash it over the whole pond. Large water exchange is an effective method.

The fourth situation: drug effects cause reduced feed intake by fish. To prevent and treat fish diseases, the use of trichlorfon, copper sulfate, clonidine hydrochloride, pyrethroid drugs, etc. causes reduced fish feed intake, usually with an impact lasting 2 days to 3 days.

Highly toxic drugs should be used less or not at all. High-efficiency and low-toxicity aquatic drugs can be used to reduce the impact of medication on fish. After the fish body recovers to health, water should be changed promptly or the fish should be detoxified.

The fifth situation: sudden temperature changes cause reduced feed intake by fish. When cold air suddenly arrives, the feed intake of snakehead and soft-shelled turtle can be reduced by one-half to two-thirds; in hot and stuffy weather, fish feed intake declines to varying degrees. The impact can be eliminated through temperature regulation, such as shading or adding insulation sheds.

The sixth situation: during the breeding season, fish will experience reduced feeding or stop feeding. Therefore, in the process of commercial fish farming, this situation should be avoided as much as possible. In the process of crucian carp farming, reducing water flushing into the fish pond during the breeding season and fertilizing the water quality are effective methods to shorten the impact of reproduction on growth.

During the production process, effective measures can be flexibly taken according to actual conditions to reduce adverse effects.