A Complete Analysis of the Key Technical Points and Methods for Mandarin Fish Farming

Mandarin fish, also known as the Chinese perch, belongs to the family Serranidae and the genus Siniperca. Its body is relatively deep and laterally compressed, with a raised back. The mouth is large, and the lower jaw is noticeably longer than the upper jaw. The upper and lower jaws, vomer, and palatine bones all bear small teeth of varying sizes. The rear edge of the preoperculum is serrated, with 4 large spines on the lower edge. The rear edge of the operculum has 2 large spines. The head is covered in scales, and the scales are small and fine. The lateral line curves upward along the dorsal arc. The dorsal fin is divided into two parts that are connected to each other; the front part consists of hard spines, and the rear part consists of soft fin rays. The body is yellow-green, the belly is grayish-white, and the sides of the body have irregular dark brown spots and blotches. A narrow black stripe runs from the tip of the snout through the eye socket to the lower front of the dorsal fin.

Selection of Forage Fish

The species of bait fish for raising mandarin fish in ponds include: silver carp, bighead carp, mud carp, mud carp (cirrhinus molitorella), Thai mud carp, crucian carp, common carp, etc. The feed conversion ratio is generally 4-5. According to the growth size and feeding amount of mandarin fish, use ponds 3-4 times the area of the mandarin fish pond to cultivate and produce sufficient bait fish to feed the mandarin fish.

1. Early-stage bait fish: In the pond prepared for stocking mandarin fish, pre-stock 1-2 million fry (fish fry) of silver carp, bighead carp, mud carp, mud carp (cirrhinus molitorella), Thai mud carp, crucian carp, etc. per mu as early-stage bait fish for mandarin fish. Feed with coarse feed such as peanut bran and wheat bran. After 15-20 days of cultivation, when the bait fish grow to 1.5-2.5 cm in body length, use 0.7 ppm copper sulfate and 0.5 ppm strong chlorine for disinfection and insect removal, then mandarin fish fry of 2-3 cm in size can be stocked for cultivation.

2. Mid-stage bait fish: In ponds of the four major Chinese carps, polyculture 200,000-300,000 fry of mud carp, mud carp (cirrhinus molitorella), Thai mud carp, etc. per mu, or cultivate fry of silver carp, bighead carp, crucian carp, etc. in dedicated ponds as bait fish for large-size mandarin fish.

3. Late-stage bait fish: In addition to self-production and self-supply, they can also be purchased externally. The late stage of farming generally enters winter, and mud carp-type bait fish are prone to freezing to death. Sufficient cold-tolerant bait fish species such as silver carp, bighead carp, and crucian carp should be cultivated to overwinter as reserve bait fish for mandarin fish in winter and spring.

Mandarin Fish Farming Techniques

1. Pond conditions: The pond area is generally 2-4 mu, with a water depth of about 2 m, mainly rectangular, with fresh water quality, little or no mud at the bottom, and complete drainage, irrigation, and aeration equipment.

2. Bait fish cultivation: Based on the principles of good palatability and low economic cost, fry and fingerlings such as silver crucian carp, white crucian carp, blunt snout bream, silver carp, and spotted silver carp can be selected as bait fish. Use the idle period before stocking mandarin fish in the pond to cultivate early-stage bait fish. You can breed crucian carp or bream fry and fingerlings yourself, or stock various fry about 20 days before mandarin fish are stocked, with a stocking rate of 400,000-600,000 per mu. The rearing method is to feed with soybean milk or other feed. In the middle and late stages, bait fish must be raised in dedicated ponds. It is advisable to use multi-pond, high-density rearing, harvesting in batches, and gradually thinning out, so as to ensure that the bait fish grow in sync with the mandarin fish.

3. Mandarin fish fingerling stocking: The stocking time is generally June, and the stocking size should preferably be 6-10 cm. The advantage is a high survival rate after stocking and fast growth. The general stocking rate is 500-800 per mu.

4. Bait fish feeding: During the adult fish farming period, the fish should be able to eat their fill every day. If there are too few bait fish and the fish go hungry, this will affect the growth of mandarin fish or lead to cannibalism.

5. Water quality regulation: The water quality of mandarin fish ponds must be well regulated, and water should be changed frequently. The high-temperature season from June to September is the peak feeding period. Water should be injected and drained once a week, with each water change of 0.4 m, maintaining pond water transparency above 40 cm.

Stocking Techniques for Mandarin Fish

1. Sources and capture of fingerlings

① Source of fingerlings: It is currently the high-temperature season, with very high temperatures, and the fingerlings have weak constitutions, so they are generally not suitable for long-distance transport. The source of supplementary fingerlings is mostly solved locally through adjustment, or they can be caught nearby in natural waters. The capture site for the fingerlings is required to be very close to the stocking site, and capture and stocking should be closely connected. The time the fingerlings are out of water must not be too long; it is best to stock them while catching them. If this cannot be done for the time being, they can first be temporarily kept in cages or held in a seine net for handling, but the time should preferably not exceed two hours. It is strictly forbidden to handle fingerlings out of water.

② Capture of fingerlings: The capture and stocking of fingerlings should always adhere to the principle of catching quickly and releasing gently. When catching, you must be careful and operate slowly, trying not to injure the fish body. The capture time can be set in the morning and evening when the weather is cool. Capture tools should use tools that do not injure the fish body, such as large seine nets and sleeve nets. For capture in the same water body, the number of seine hauls cannot be too many, so as to avoid causing fish to gasp at the surface and die. Gill nets will injure the fish body and cause scales to fall off, so they should not be used. Catching by draining the pond will cause the fish to suffocate in the muddy water and will also burn the fish body due to shallow water, so it is best not to use this method either. For feeding fish, bait can be used to lure them during feeding, and nets can be used to intercept them on their activity routes for concentrated capture. This is also a very good capture method.

2. Stocking and management of fingerlings

① Preparation before stocking: Before stocking fingerlings, all preparatory work should be done well. Check whether the water inlet and outlet are intact to prevent leakage. If problems are found, they should be solved immediately. Second, observe the conditions of the water body to be stocked, especially understand the fish escape situation in the pond, so as to find out the details and facilitate determining the stocking species and stocking amount. Finally, the water body should also be improved once. Because the current temperature is high, water bodies are generally turbid, there is more dirt in the water, water quality is very poor, and bacteria are prone to reproduce. Quicklime or alum, etc., should be dissolved in water and splashed to clarify the water body and purify the water quality. If the water body is relatively lean, a little fertilizer should also be applied to cultivate natural food in the water.

② Stocking operation: In order to reduce stocking mortality and ensure the stocking effect, supplementary fingerlings should be selected. The selected fingerlings are required to have intact scales and fins, jump vigorously, swim lively, be plump and strong, and be free of disease and injury. Fingerlings that are thin and weak, slow to respond, have congestion on the body surface, or have mechanical injuries should all be removed. The stocked species can be determined according to the source of fingerlings and stocking needs, but the stocking size should preferably be large, and the stocking density can adhere to the principle of sparse stocking, so that by the end of the year all adult fish reach commercial specifications, reducing the adverse effects brought by a short growth period and ensuring farming benefits. When stocking, the fingerlings must be disinfected with drugs before being put into the water body, so as to prevent fish from carrying disease into the pond and causing the spread of fish diseases. Generally, 2%-3% salt water or 1 ppm-2 ppm trichlorfon crystals, etc., can be used to soak them for 3-5 minutes.

③ Management after stocking: After the fingerlings are stocked, according to the species, quantity, and other conditions of the stocking, conscientiously do a good job in feeding, fertilizing, water quality regulation, fish disease prevention, and other work. Feed is generally mainly concentrated feed to accelerate the growth of the fish body. The daily feeding amount is more suitable at 5%-8% of the total weight of the pond fish, specifically with a slight remainder after feeding as the standard. If there are many filter-feeding fish such as silver carp and bighead carp stocked in the pond, more fertilizer can be applied. Fertilization should follow the principle of small amounts and multiple applications. Organic fertilizer should be fully fermented before being applied to the water body, with an application rate of 50 kg-100 kg per mu. For chemical fertilizer, ammonium bicarbonate (5-8 kg per mu) or urea (3-5 kg per mu) can be dissolved in water and splashed over the whole pond to improve water quality. Within 7-10 days after stocking, splash strong chlorine (0.3 ppm), bleaching powder (1 ppm), etc., to kill bacteria. At the same time, splash a mixture of trichlorfon crystals (0.4 ppm), copper sulfate (0.5 ppm), and ferrous sulfate (0.2 ppm) at intervals to kill parasites and effectively prevent the occurrence of fish diseases.