Sustainable Fish Feed: The Alternatives to Fishmeal That Are Changing Aquaculture

One of the most significant criticisms of aquaculture as a sustainable food production system is the dependence of many farmed fish species on fishmeal and fish oil derived from wild-caught forage fish — anchovies, herring, menhaden, and similar species. A feed input that depletes wild fish populations to produce farmed fish is not, by most definitions, a sustainable system. The aquaculture feed industry has been working on this problem for two decades, and the alternatives being developed and commercialized are changing the nutritional composition of aquaculture feeds in ways that have significant implications for feed efficiency, fish health, and the environmental footprint of aquaculture production.

Plant-Based Protein Alternatives

Soybean meal has been incorporated into aquaculture feeds as a partial fishmeal replacement for decades, and it works well for omnivorous species like tilapia and catfish that can digest plant protein efficiently. Carnivorous species like trout and salmon are less capable of efficiently utilizing high plant-protein diets because their digestive systems are adapted for animal protein. Current research has focused on processing plant proteins to remove anti-nutritional factors and improve digestibility for carnivorous species, with meaningful progress in recent years. Canola protein, corn gluten, and various legume proteins are all under active development as fishmeal alternatives.

Insect Protein

Black soldier fly larvae (Hermetia illucens) has emerged as the most promising insect-based fishmeal alternative in aquaculture research. BSF larvae can be raised on organic waste streams — food processing byproducts, agricultural waste — converting low-value organic material into high-quality protein and fat with an amino acid profile that closely resembles fishmeal. Several commercial insect protein producers are now supplying aquaculture-grade BSF meal at prices approaching conventional fishmeal. Feed trials with catfish, tilapia, trout, and salmon have shown acceptable or improved growth performance with BSF inclusion rates of 20 to 50 percent fishmeal replacement.

Single-Cell Proteins

Algae, yeast, and bacterial biomass produced through fermentation processes represent a category of single-cell proteins that can be produced at industrial scale without land or water inputs proportional to conventional agriculture. Algae-derived omega-3 fatty acids — the nutritional equivalent of fish oil without the fish — are already commercially available and are used in some premium aquaculture feeds. The scaling of single-cell protein production to commercial aquaculture feed application levels is actively underway, and the next decade is likely to see significant commercial incorporation of fermentation-derived proteins in mainstream aquaculture feed formulations.