Review on the use of insects in the diet of farmed fish: Past and future

• Insects AA profile is usually adequate for both freshwater and marine fish.
• Good results with non-defatted mealworms and silkworms but defattening meal advised.
• Process of insect meal improves nutritive value, digestibility and palatability.
• Finishing FM-rich diets in marine fish to recover n-3 HUFA in fillets.
• Mealworms, silkworms and maggots were the most potent FM alternatives.

The decrease in the availability and the increase in the prices of fishmeal and fish oil have prompted the search for sustainable alternatives for aquaculture feeds. Insects, which are part of the natural diet of fish, leave a small ecological footprint and have a limited need for arable land, may represent a good candidate. Over the last decade, studies of the replacement of fishmeal with insects in the diet of fish have emerged and the promising results have encouraged further research. The present review displays these results in tables and emphasizes the achievable dietary inclusion levels. It discusses the potential of locusts, grasshoppers, termites, yellow mealworms, Asiatic rhinoceros beetles, superworms, domesticated silkworms, common houseflies, common mosquitoes and black soldier flies for use as fishmeal and/or fish oil replacement in the fish diet. The review succinctly compares the composition of the insects with the requirements of the fish (proteins and amino acids, lipids and fatty acids, vitamins and minerals). This review also discusses the potential hurdles of using insects in fish feeds (toxicity of insects through bioaccumulation, deficiencies in amino acids or fatty acids, chitin content, palatability, digestibility), and the available ways of avoiding these drawbacks (control of the dietary substrate of insects in mass rearing units, manipulation of the diet of insects, mixture of dietary proteins, use of aquatic insects, processing of insect meal). Finally, it suggests paths worthy of future research on these new fishmeal alternatives.