Paddlefish Farming Techniques and Conditions: Both Monoculture and Polyculture Require the Addition of Silver Carp

SummaryModels: There are two models, monoculture and polyculture, but both require the addition of silver carp, which can control the amount and growth rate of algae and avoid water eutrophication. Density: Under the monoculture model, at a body length of 50-60 cm and a weight of 1 kg, 80-100 fish per mu; at 2-3 kg, 40-50 fish per mu; under the polyculture model, at a body length of 25 cm, 50-70 fish per mu; at a body length of 50-60 cm, 20-50 fish per mu. Harvesting: A single seine haul can catch about 85%.

Paddlefish are appearing on our dining tables more and more frequently, and have become a popular aquatic product in recent years. Many farmers have also begun to enter the paddlefish farming industry. To succeed in the paddlefish farming industry, mastering mature farming techniques is essential. Below, let us look at the farming techniques and conditions for paddlefish.

Paddlefish Farming Conditions

1. Paddlefish have a very wide temperature tolerance. They are neither afraid of low temperatures nor unable to endure high temperatures. In winter, even if the water surface freezes, as long as there is still sufficient dissolved oxygen in the water, paddlefish can still live in the water beneath the ice. In summer, even if the surface water temperature of the farming pond often exceeds 35°C, paddlefish can still grow normally.

2. For the farming site, it is recommended to choose a steep-sided reservoir in a low-lying area. The water area of the farm should be large enough, with a water depth of at least 6 m or more; dissolved oxygen is suitable at 6~9 mg/L, pH is suitable at around 7-8.4, total hardness is suitable at around 20-40 mg/L, ammonia nitrogen at around 0.02-0.06 mg/L, and nitrite at around 0.0015-0.01 mg/L. Good water quality is sufficient.

Fry Rearing Methods

Generally, the trough fry rearing method is adopted. After hatching, they are reared in troughs for 30~40 days until they reach 3~5 cm and are stocked into ponds. This process is key to the survival of the fry.

1. Trough conditions: The area is about 10 sq m; rectangular or circular is acceptable, with no sharp corners, convenient water inlet and drainage, and escape-prevention facilities. The water quality is excellent, with no pollution or toxic substances, and it must be filtered before use. Water exchange is carried out 2 times per hour (water is stopped for half an hour during feeding). The water temperature is between 16~28°C, and dissolved oxygen is above 5 mg/L.

2. Stocking density of paddlefish fry: At the beginning, 200 fish per sq m; when they grow to 5 cm, the density drops to 100 fish per sq m.

3. First feeding bait and feeding: The first feeding bait for paddlefish is zooplankton, and a combination of egg yolk and zooplankton can also be used. The best first feeding bait for paddlefish is the copepod Cyclops. If feeding Cyclops, the timing of release must be well controlled, so that the Cyclops do not pinch and break the yolk sacs of the fry, causing mass mortality of the fry. The daily feeding frequency should preferably be 4~8 times; feeding is also required at night in the indoor rearing facility, and the amount should be slightly in excess. The bait initially released must pass through a 60-mesh screen to filter out large individuals and harmful aquatic insects. Later, after domestication, they can consume artificial compound feed, with the intake being about 30% of body weight. Paddlefish have very poor eyesight and will not actively seek food, so losses during feeding will be somewhat greater.

4. Daily management and precautions: Daily management requires waste removal, brushing and washing the screen windows, and keeping detailed records, etc. When the fry grow to 3~5 cm, several abnormal situations occur, such as gathering at the corners of the trough, fry biting and swallowing each other, and uneven individual sizes. The causes of these situations are uneven nutrition and excessive density. In addition, due to insufficient nutrition, the fry will also swallow air bubbles on the water surface, causing the digestive tract to swell and bleed until death. About 80% of fry deaths are caused by biting and swallowing each other, and about 20% are caused by congestion of the digestive tract. Therefore, fry after 3~5 cm should be released into ponds with balanced and sufficient bait and a large water body.

Pond Fingerling Rearing Methods

Fry of 3~5 cm are reared in the same year into large-size fingerlings with a body length of 20~30 cm and a body weight of 200 g, which takes 3~4 months.

1. Pond requirements: Ponds with a water surface of 3~5 mu, a water depth of 1.5~2 m, and convenient water inlet and drainage are better. Each pond should be equipped with one 1.5 kW aerator. Before stocking, the pond must be cleared with water retained, using 150~200 kg of quicklime per mu to kill miscellaneous fish, aquatic plants, and so on. The pond water temperature can be 2~37°C, with the optimum being 25~32°C.

2. Stocking in fertilized water: One week before stocking, fertilization must be carried out to cultivate good water quality. The fertilizer is generally night soil (400~500 kg/mu) and chicken manure, cow manure, etc. After 3 days, soybean milk is spread into the pond at 5 kg/mu. Before stocking, the fry should also be scooped once more with a fry net to remove tadpoles and debris. The temperature difference between the pond water and the water in the container holding the fish must not exceed ±3°C, and the operation should preferably be carried out in the evening.

3. Reasonable sparse rearing: The main farming method is monoculture, and a small number of bottom-dwelling fish and herbivorous fish can be added at the same time. Do not add bighead carp, silver carp, or fierce fish. The stocking density is preferably 100 fish per mu. During the farming process, in addition to fertilizing to cultivate the water body, soybean milk (2 kg/mu), cake meal and floating wheat flour, bran, or special pellet feed must also be fed. The water quality must always be maintained as fertile, lively, tender, and refreshing.

4. Strengthen management: Insist on patrolling the pond every day and carefully keep farming records.

5. Fish diseases and treatment: Generally, fingerlings above 10~15 cm rarely die, but there have been several reports of parasitic and bacterial diseases. Because paddlefish are very sensitive to drugs, especially to heavy metal salt drugs, caution is required when using medication. Occasional fish diseases are mainly nematodes and trematodes, and they can be treated with a bath of 2×10-6 potassium permanganate or less than 75×10-6 formalin. During the juvenile stage, copper sulfate and chlorine-containing drugs are prohibited, and the soaking concentration of antibiotics is about 4×10-6. After being reared into large-size fingerlings of 30~40 cm, they can be directly released into reservoirs, or they can continue to be farmed in ponds.

Paddlefish Farming Techniques

1. Farming methods: Monoculture and polyculture are both acceptable, with polyculture as the main method, and the matching ratio depends on local specific conditions. Generally, silver carp + herbivorous fish : sturgeon = 6~7:1; herbivorous fish : silver carp = 1:1.5~3. Regardless of monoculture or polyculture, silver carp must be added, because silver carp can control the amount and growth rate of algae and avoid water eutrophication.

2. Stocking density

① Monoculture. At a body length of 50~60 cm and a weight of 1 kg, 80~100 fish per mu; at 2~3 kg, 40~50 fish per mu.

② Polyculture. At a body length of 25 cm, 50~70 fish per mu, growing to 1 kg by the end of the year; at a body length of 50~60 cm, 20~50 fish per mu, growing to 2~3 kg by the end of the year. In the third year, 7~8 fish per mu. For adult fish pond farming, it is not suitable to polyculture in small-area or intensive high-yield ponds, because intensive ponds have high yield and high density, dissolved oxygen fluctuates greatly, and continuous harvesting and restocking are all very unfavorable to paddlefish.

3. Adult fish harvesting: The catch rate is relatively high; one seine haul can catch 85%.

Market Prospects for Paddlefish Farming  

Previously, the industry knew very little about paddlefish. As fry rearing technology gradually matured, the supply of artificial fry increased accordingly, and the farming scale of paddlefish began to gradually expand in recent years. Paddlefish also gradually became familiar to more farmers and consumers. The annual spawning period of paddlefish is only in March and April, and the reproduction period is relatively short; if the weather is good, about 15 days. Constrained by the number of broodstock and the relatively short reproduction period, the supply of seedlings is therefore relatively tight.  

At present, domestic paddlefish farming in China is mainly concentrated in the Guangdong region, with relatively little farming in other provinces. With the continuous increase in the supply of artificial seedlings and market demand, pond intensive farming and polyculture of paddlefish are now developing rapidly in the Pearl River Delta region, and reservoir cage farming is also increasing day by day. 

Although paddlefish are now gradually becoming known to everyone, and compared with before, its demand is gradually increasing, its market still has a great deal of room for development, and there are still many people who have never eaten paddlefish and know nothing about it at all. Therefore, the market prospects for paddlefish are very great, and there may still be many blank areas.