The southern bigmouth bream is a highly valued economic fish, commonly found in large water bodies south of the Yangtze River. It exhibits strong adaptability and fast growth when raised in captivity, making it a popular choice for aquaculture. The fish has tender and delicious flesh with few intermuscular bones, although it does not respond well to artificial fertilization. Due to its high market demand and ease of breeding, it has become a favorite among both consumers and producers.
In recent years, cage culture has gained popularity for raising large southern bigmouth bream. After domestication, these fish show good adaptability to cage environments and artificial feed, leading to rapid development in this method. In general, after more than 150 days of farming, survival rates can reach up to 70%, with each square meter of cage producing between 65 to 100 kg of marketable fish. To achieve high yield and efficiency, proper management is essential.
First, the water conditions must be suitable for the southern bigmouth bream. This species can grow year-round but thrives particularly in summer and autumn, gaining 3–5 grams daily. It can survive in temperatures ranging from 0°C to 38°C, with optimal growth between 25°C and 28°C. Growth slows significantly below 18°C or above 30°C. The fish remains active even at 8°C, and can survive at 32°C without food. Water with dissolved oxygen above 5 mg/L supports the fastest growth, while levels below 2 mg/L may cause stress, and below 1 mg/L can lead to suffocation. A pH range of 7 to 8.4 is ideal. Therefore, cages should be placed in sunny, sheltered areas with open waters, stable water levels, clean and unpolluted sources, convenient transportation, and some wave action or slow currents. The water depth should be over 5 meters, with transparency exceeding 80 cm, and water temperature above 22°C for 3–5 months. Dissolved oxygen should be above 3 mg/L, and pH within the suitable range.
Second, cage setup should follow standardized practices. Experts recommend a three-stage cage system: first, stocking 4–5 cm fingerlings in small cages, then moving them to medium-sized cages as they grow, and finally transferring them to large adult cages. The net mesh sizes are 0.6–0.8 cm, 1–1.5 cm, and 2.5–3.5 cm, respectively. Each cage measures 5m x 5m x 3m, using a single-layer polyethylene woven net. The outer mesh size is 3.5–5.5 cm, and double-polyethylene nodules are used to secure the cage. Bamboo frames are common, with cages staggered in lines, spaced 5 meters apart, and 30 meters between groups. A feed table made of thick cloth and bamboo is placed at the center of each cage. Nets should be installed 10 days before fish are introduced to allow algae to grow, preventing injury to the fish.
Third, stocking should be done carefully. Selecting pure, healthy larvae is crucial. Large mouth larvae have longer upper caudal fin leaves, yellowish-brown coloration, and active behavior, while soil-type larvae have shorter fins, black coloration, and poor growth. Fry should be stocked at a density of 400–600 per square meter when they reach 4–5 cm. After 15–20 days, they are sorted and moved to different cages. Fish over 8 cm are reared at 300–400/m², then moved to larger cages at 16 cm, with a density of 200–250/m². When they reach 25g, they are transferred to the final stage at 120–150/m². For annual releases of 400g fingerlings, stocking density should be 30–50 per square meter.
Fourth, feeding should be scientific. As a carnivorous species, it preys on fish, shrimp, and aquatic insects. During the fry stage, it needs to transition from live bait to artificial feed. Cage-raised fish are mainly fed compound feed. Four types of feed are commonly used: conversion feed, fingerling feed, adult feed, and autumn feed. Protein content ranges from 40% to 50%, with adult feed containing around 35%. Feed formulas include fishmeal, starch, soybean meal, yeast, peanut powder, bone meal, and fish oil. Pellets must be firm to prevent disintegration in water. Feeding stations are placed every 10 square meters, suspended 20–30 cm above the bottom. Feeding frequency and amount vary depending on fish size. Daily feeding rates range from 8–10% for smaller fish to 1–3% for larger ones. Last feeding is usually around 10 PM. For every 1 kg of large mouth bass, about 2–3 kg of compound feed is needed.
Finally, daily management is critical. Regular checks for cage damage, cleaning of feed tables, and removal of leftover food are necessary. Cages should be cleaned every 5–10 days to prevent algae buildup. Fish growth should be monitored regularly, and records of water temperature, feeding, dissolved oxygen, mortality, and disease should be kept. Disease prevention is key—fish should be disinfected before stocking, and overcrowding should be avoided. Medications can be added to feed, but caution is required due to the fish’s sensitivity. Common diseases include white mouth, small melon worm, hemorrhagic disease, enteritis, and rickets. Professional help should be sought for accurate diagnosis and treatment.
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