Sustainable Aquaculture: Insect Meal as Fish Feed

The soaring population growth is significantly amplifying the need for aquaculture, the cultivation of water-dwelling organisms like fish, mollusks, and crustaceans. Given the high protein requirements of fish, climate change implications, and the diminishing availability of marine fish stocks due to overfishing, researchers are actively seeking more sustainable, economic, and ecological alternatives.

Fish on farms are typically provided with two types of feed: plant proteins, such as oilseed meal, cereal protein, and grain legumes, which have been recently linked to adverse gut effects; and Processed Animal Proteins (PAPs), derived from animal by-products like poultry meal and blood meal. PAPs now also encompass insect meal, approved as fish feed by the European Commission in December 2016.

Insect meal, primarily composed of larvae, possesses similar nutritional attributes to fish meal, including essential amino acids, high lipid content, vitamins like B12, and minerals such as iron and zinc. It also exhibits antioxidant and antimicrobial properties. The nutritional composition varies based on factors like insect type, breeding, and protein production process. The larvae of Hermetia illucens, commonly known as the Black Soldier Fly, has proven beneficial for insect meal production. These larvae feed on organic waste, grow rapidly, and have a minimal environmental impact, making them ideal for industrial-scale breeding and flour processing. They contain 60% protein and 40% lipid, proving more nutritious and palatable to fish than plant feeds and fishmeal currently in use. However, to maintain high palatability and protein source, the larvae need to undergo a defatting process to remove lipids, which might otherwise hinder fish digestion.

Research conducted on various farmed fish species (rainbow trout, Japanese sea bass, African catfish, Atlantic salmon, yellowtail, Japanese carp, and eel) revealed that substituting fish meal and vegetable feeds with H. illucens meal resulted in no adverse effects on fish growth. In fact, it increased growth performance in African catfish and yellowtail, without compromising the chemical and physical quality of the fillets.

However, the European Union necessitates further exploration to establish the efficiency of this new feeding method and its administration process, given that each fish species has distinct protein requirements. It is equally crucial to determine the appropriate lipid removal process, which, if not properly executed, could limit palatability and digestibility in fish. The right degreasing method could also help address an additional concern: the alteration of fats in the meat, resulting in a decrease in beneficial polyunsaturated fats and an increase in less healthy saturated and monounsaturated fats.

However, it is clear that H. illucens may represent a future and encouraging dietary alternative in aquaculture. In fact, the use of this new food source could bring environmental benefits: first of all, the repopulation of fish species in seas, lakes and oceans; the reduction of pollution and lowering of costs; and finally, the decrease of cultivated land for plants used in the production of plant meal and feed. The use of H. illucens thus goes a long way toward creating a kind of circular bioeconomy, which is essential nowadays for greater environmental sustainability.