Insects as feed for trout
A problem with fish farming is that commercial fish feed contains fishmeal and fish oil. These raw materials are expensive and not very sustainable, because the already high demand for fish risks leading to overfishing in order to produce fish feed. In addition, the caught fish could be used directly for human consumption instead. Could insects be an option?
The aquaculture industry is looking for more sustainable feed materials. A possible alternative are insects. Insects are a natural part of fish’s feed and can be grown on substrates that cannot be used for human consumption, such as food waste.
In this study, we tested two insect species, house cricket (Acheta domestica) and larvae of superworm (Zophobas morio), as live feed for trout. Both species are already used today as feed in the pet-feed sector, so there is an established production.
We fed the fish for 60 days in five groups with different feeds: commercial feed only, commercial feed in combination with 25% house cricket or 25% superworm or 12.5% of each species, or 100% insects in a mixture with half of each species. We found no significant differences in growth, survival or metabolism between the groups. However, protein efficiency decreased with increasing proportion of insects. The proportion of nutritional valuable omega 3 fatty acids in the fish muscle decreased with increasing amount of insects in the feed, and fish that had received 100% insects tasted less good.
In conclusion is it possible to replace fishmeal and oil in fish feed with insects to some extent, however, a too high proportion of insects can lead to inferior taste and decreased nutritional value. In addition, at present insects are still too expensive to produce to be economic feasible.
Turek J, Sampels S, Tilami SK, Cerveny D, Kolarova J, Randak T, Mraz J, Masilko J, Steinbach C, Burkina V, Kozak P, Zlabek V. 2020. Insects in the feed of rainbow trout, Oncorhynchus mykiss (Actinopterygii, Salmonidae): Effect on growth, fatty acid composition, and sensory attributes. Acta Ichthyologica et Piscatoria 50 (2), 171-181.