Developing an algae-based food to replace fishmeal in fish farming

Fish prove to be a reliable source of high-quality protein and polyunsaturated fatty acids that may decrease risks of chronic diseases such as diabetes, hypertension and cancer. Although fish is an excellent dietary source of those nutrients, the average annual fish consumption is only 6.5 kilograms per person in the U.S., partially due to limited local production and high cost of imported seafood. Expansion of local and domestic aquaculture is also hindered by the high cost of fish feed, which relies on expensive, animal-based ingredients. Fish producers have looked to plant-based solutions for fish feed ingredients, but challenges persisted in finding the right recipe that both keeps costs down and keeps fish healthy and nutritious for consumption.

This project sought alternative diets for fish, substituting expensive fish meal, fish oil and astaxathin — a bioactive antioxidant compound that occurs naturally in certain algae — with different combinations of microalgae, soybean meal and other plant-based ingredients to find the optimal mix. The research included two parallel experiments on more than 600 fish, across 16 weeks, examining 12 diet variables. Performed in well-equipped federal research facilities, the project team focused their fish diet study on rainbow trout, which is cultured in 69 countries and supports a $2.4 billion global industry. The U.S. alone produces over 20,000 metric tons of rainbow trout in freshwater systems annually, making it the eighth-largest producer worldwide. A staple for New York state hatcheries and farms, rainbow trout also has one of the highest protein requirements among fish and is a well-established model for aquaculture research, making it a prime candidate for this study.