Detailed Explanation of Seed Selection and Breeding Techniques for Fengchan Crucian Carp

Fengchan crucian carp, also known as Baihua crucian carp, is a new all-female crucian carp variety bred by the Fish Research Laboratory of South China Normal University using fish cell engineering technology. Its body color is rather pale and its shape is well-proportioned and graceful, similar in body form to the Northeast silver crucian carp (Carassius auratus gibelio), with its back between Pengze crucian carp and high-back crucian carp, its flesh relatively firm, and its taste fresh and sweet. It has a large individual size, fast growth, omnivorous feeding habits, strong disease resistance, and high population yield; it can overwinter naturally in fish ponds, and because it is all-female, it will not reproduce on its own in fish ponds. It has fast production speed, a beautiful body shape, strong adaptability, and tender, fresh flesh. Overall, it is currently the crucian carp breeding variety with the best comprehensive performance.

Breeding Techniques

To achieve high-yield benefits when crucian carp is the main species stocked in ponds, breeding techniques are key, and attention should be paid to the following aspects:

Correctly distinguish the quality of fingerlings.

When purchasing crucian carp fingerlings, farmers should, based on the biological characteristics of the main crucian carp breeding varieties, correctly distinguish inferior fingerlings to avoid being deceived and suffering losses, and must choose high-quality fry.

Choose the main breeding variety well

At present, the main crucian carp varieties cultured are Fengchan crucian carp, Pengze crucian carp, and Xiangyun crucian carp. Among them, Xiangyun crucian carp has the fastest growth rate, followed by Fengchan crucian carp, and finally Pengze crucian carp.

Design a good stocking density for fingerlings

In order to reduce breeding costs, it is best to cultivate large-size fingerlings yourself.

1. When using ponds to cultivate crucian carp fingerlings, stocking 80,000 to 120,000 crucian carp summer fry per mu can reach a grow-out size of 50 g to 60 g. 2. When conducting grow-out culture of crucian carp, when the average size of fingerlings is 50 g to 60 g, stocking 1,500 to 1,800 crucian carp fingerlings per mu is most ideal, and the size of marketable fish can reach 350 g to 400 g.

Determine the companion species

To cultivate large-size crucian carp fingerlings, do not stock grass carp and crucian carp as companions; instead, choose silver carp and bighead carp, with their number accounting for about 20% of the main cultured crucian carp, and bighead carp accounting for about 10% of silver carp. The stocking time of companion species should not be too early; in particular, introducing bighead carp too early has a greater impact on the domestication of crucian carp.

Fingerling domestication

1. Domestication is relatively easy during the fingerling cultivation stage. After domestication, the fingerlings have a short time to surface and compete for food during grow-out culture, making management convenient.

2. During domestication, adding an appropriate amount of additives to the feed can shorten the domestication time and increase the feeding area and amount for crucian carp.

3. The impact of density on domestication. High density and a large population make domestication easier. When the density has been determined and cannot be changed, the pond water level can be lowered to relatively increase the density, which is beneficial for domestication and can also raise the pond water temperature to promote fish growth.

4. Companion silver carp and bighead carp fingerlings should be stocked after the main cultured crucian carp have formed the habit of surfacing to compete for food. 5. During the domestication period, the water quality should preferably be “clear and lean” rather than “turbid and fertile.” 6. During domestication, management personnel need to be patient and careful. Feed particle size and feeding rate

1. The standard for selecting crucian carp feed particle size is “choose smaller rather than larger.” Generally, when crucian carp size is below 10 g per fish, choose a feed particle size of 0.5 mm; at 10 g to 30 g per fish, choose 1.5 mm; at 75 g to 100 g per fish, choose 2.0 mm; at 150 g to 300 g per fish, choose 2.4 mm; and at more than 300 g per fish, choose 3.2 mm. 2. The feeding ability of fish is directly affected by fish size and pond water temperature, so the feeding rate should be adjusted randomly according to actual conditions and should not remain unchanged.

Fish disease prevention and control

Although crucian carp has strong disease resistance, in recent years hemorrhagic anchor worm disease of crucian carp has still been found. Although the incidence of this disease is not high, once infected and allowed to develop, it can also cause mass death of crucian carp. Severely affected crucian carp mainly show: floating and slow swimming (weakness), pale white color; needle-like parasite bodies can be seen parasitizing on the abdomen and both sides of the dorsal ridge (fine-scaled areas) of the fish body surface; at the attachment sites of the parasite bodies there are congested red spots the size of mung beans or peas, the scales at the lesion sites are loose or shed, mucus increases, and a few form obvious ulcers. The pathogen is Lernaea cyprinacea. Main causes: first, pond clearing is incomplete or the pond is not cleared, allowing the pathogen to breed when conditions arise; second, fingerlings whose body surface is damaged at stocking (or whose body surface is injured due to careless production operations), creating an opportunity for pathogen parasitism.

Prevention methods: ① 1 day to 2 days before crucian carp fingerlings are stocked into the pond, splash 2.5% trichlorfon powder over the whole pond. ② For small-area main culture ponds, during the disease season, splash 90% crystal trichlorfon over the whole pond every half month; for large-area crucian carp polyculture ponds, during the crucian carp growth season, hang baskets (bags) of trichlorfon around the feeding area, 1 time to 2 times per month, hanging continuously for 2 days each time. Treatment method: during culture, when signs of disease appear, observe and inspect in time, and after diagnosis, splash a mixture of crystal trichlorfon and ferrous sulfate over the whole pond at one time.