Sizing Nursery Tanks: Managing Stocking Densities and Grading Schedules to Stop Cannibalism
The Silent Harvest of the "Shooters"
In any batch of catfish fry, 5% will grow twice as fast as their siblings due to aggressive feeding genetics. If left unsorted, these large individuals ("shooters") consume smaller fish whole, leading to alarming batch count shrinkages.
The Rigorous 14-Day Grading Rhythm
- Day 1 to 14: Stock 2,000 fingerlings (4cm) per 1,000-liter circular nursery tank with continuous aeration.
- Day 15: Drain water to 10cm, pass stock through graded perforated sorting screens (mesh sizes 6mm, 8mm, 10mm).
- Segregation: Divide the population into three separate tanks: Shooters (Alpha), Medium (Beta), and Smaller (Gamma).
- By feeding each group feed pellets precisely matched to their mouth gape, cannibalism drops from 35% down to under 2%.
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