Grading Fish - Tech Talk 69
Commercial aquaculture requires periodic size grading of most species to prevent cannibalism, reduce growth rate variation and improve yield. When fish are not graded it is common to have a harvest with 25% of the fish being undersized. This is due to the larger fish dominating the others and consuming more food.
Efficient management requires knowledge of growth rates, stocking densities, feed requirements and general health—all of which can be learned through grading and counting.
Graders can be species specific. Selecting the wrong grader type for your species and fish size can make the grading process inefficient and/or damage the fish, so ask others for their experience before you buy.