Detailed Explanation of Key Technical Points for Cross-Season Pond Fish Farming

China's traditional pond fish farming technique involves stocking fingerlings at the beginning of the year and harvesting for market at the end of the year. This production model has been accepted by the vast majority of fish farmers. However, the prominent problem with this farming method is concentrated marketing in winter, when product prices are relatively low, and this is particularly pronounced for farmers raising conventional species. Cross-season pond fish farming technology delays the time to market, allowing both higher yields and better returns. Its main technical points are:
(1) Pond Conditions and Renovation
① Pond conditions: Fish farming ponds require an average water depth of over 15 m, no seepage or leakage, and reasonably convenient water sources.
② Pond renovation: After the pond fish are harvested for market each year from August to October, repair the pond embankments. Where conditions permit, remove excess silt, then use 150 kg of quicklime per mu of water surface for pond clearing and disinfection.
③ Apply base fertilizer: Apply 200-300 kg of decomposed manure per mu of water surface as base fertilizer.
④ For cross-season fish farming where grass carp fingerlings are stocked, allocate 0.2 mu of field or land per 100 grass carp for growing grass to feed the fish.
(2) Fingerling Stocking
① Fingerling sources: Fingerlings can come from original pond polyculture or purchased fingerlings as the source for cross-season farming.
② Stocking time and fingerling disinfection: The stocking time is from mid-August to early October each year. Before stocking, soak the fish in 5% salt water for 5-10 minutes. For ponds mainly raising grass carp, the grass carp need to be injected with inactivated grass carp hemorrhagic disease vaccine.
(3) Stocking Quantity and Polyculture Ratio
① Polyculture model: Stock 100-150 grass carp per mu at a size of 1-2 fish per kg, 100-150 silver carp, 30-40 bighead carp at 2-3 fish per kg, 150-200 Pengze crucian carp at 5-10 fish per kg, 30 common carp at 4-5 fish per kg, 50 bream at 5-6 fish per kg, and optionally polyculture other species such as yellow catfish and catfish.
② Crucian carp-based farming model: Stock 1,000-1,200 Pengze crucian carp per mu at 6-10 fish per kg, 100-130 silver carp at 4-6 fish per kg, and 200-300 yellow catfish at 20-30 fish per kg. Both farming models can be used to polyculture summer fry in May of the following year, stocking 300 grass carp, 300 silver carp, and 200 bighead carp per mu of water surface.
(4) Feeding Management
① Feed feeding: After stocking, feed pelleted feed at 3-4% of fish body weight, twice daily, once in the morning and once in the afternoon, using the same feeding method as pond fish farming. After the end of November, as temperatures drop, gradually reduce the daily feeding amount to 1-2% of fish body weight, and change feeding frequency from twice daily to once at noon each day (no feeding during extremely severe weather). After the end of February of the following year, gradually increase the feeding amount back to 2-4%.
② Green feed feeding: Throughout the entire rearing period and overwintering, green feed must be fed. The principle is to feed only as much as the grass carp can finish in the day with nothing left over. Before mid-December, feed twice daily; in winter, feed once daily; from early March, change back to twice daily. After mid-March, the daily amount of green feed should be appropriately controlled, with the principle of feeding to about 80% satiation (roughly controlled at 0.3-0.4 kg of grass per kg of grass carp), which can help avoid triggering fish diseases.
③ Water quality control: Throughout the entire rearing process, pond water must be kept fertile, lively, refreshing, and tender. In winter, add water to the maximum level. In spring, when weather changes are relatively frequent, pay attention to regulating water quality to avoid fish kills from pond turnover.
(5) Harvesting for Market
When the fish have been raised to May-June, most pond fish can reach market size. At this point, based on market fish prices, market-sized fish can be gradually harvested in rotation until harvesting is completed by mid-August, when the next round of farming begins.
(6) Precautions
① In ponds mainly raising grass carp or with a relatively large grass carp stocking density, disease outbreaks in grass carp occur about one month earlier than in conventionally farmed ponds, so fish disease prevention work needs to begin in mid-March.
② In cross-season fish farming, the fish carrying capacity from April to June each year is greater than in conventionally farmed ponds, so the possibility of surfacing and pond turnover is greater during this period. In seasons with relatively frequent weather changes, pay attention to regulating water quality and timely adding fresh water to prevent surfacing and pond turnover.