How important is the diet composition for catfish fingerlings, compared to other factors of growth and survival? New research, published in the Journal of Insects as Food and Feed, looked at the difference between fish meal and insect meal.

The fingerling stage is important to secure good growth and health throughout the growing phase of farmed fishes like catfish. In this stage water temperature, growth and survival are the main criteria. An Italian research group therefore wanted to know how large the effect of diet formulation in this fingerling stage is and performed a pre-fattening phase trial to evaluate the effect of partial replacement of fishmeal (FM) with insect meal (Tenebrio molitor) in common catfish (A. melas) fingerlings.

Growth performance and survival rate where measured after 90 days. It was shown that fish, that received the insect meal (IM) diet reached a final mean body weight of 4.18±0.6 g, which was significantly lower than that reached by the fish meal (FM) group (5.13±0.7 g). The highest specific growth rate (SGR) was recorded at 30 days of experiment in both groups (FM = 5.17%/d; IM = 3.18%/d). At 60 days, SGR of the IM group was significantly higher (3.16 %/d) than that of the FM one (2.79%/d; P<0.05) in both groups, without showing significant differences (fm="2.50%/d;" im="2.64%/d)." the survival rate of fm group (79%) was higher than that of im one (70%; p><0.01). fcr ranged from 3.8 (fm) to 4.1 (im) without showing significant differences.>

The researchers explain: "We tested the T. molitor meal in the feeding of 28-31 days old common catfish (A. melas) fingerlings. In this phase, the most important parameters of a rearing technique are survival and growth whereas feed conversion is less important. In our trial, catfish fed on a diet in which 50% of fishmeal was substituted with mealworm meal reached a final mean body weight significantly lower than that of fish fed on a fishmeal based diet. Specific growth rate showed a good value during the first month but then it decreased in both groups at the end of the second month, remaining at the end of the trial slightly higher in catfish fed on IM diet in comparison to those fed on FM diet."

Source: Wageningen Academic Publishers