Aquaculture, otherwise known as fish farming, is the fastest growing food sector, but while it’s more sustainable than beef farming, the industry could make key changes that would make it far more environmentally-friendly. Changing what farmed fish are fed is a crucial first step.

Most aquaculture operations feed fish a combination of fishmeal and fish oil. In essence, they’re basically fed other, smaller fish. If this sounds concerning, that’s because it is. 20 percent of fish caught around the world each day are used for fish meal, meaning farmed fish operations are expected to strip the oceans of small forage fish like herring and anchovies by 2037, which would have devastating effects on marine ecosystems and human populations which rely on fish-based diets. 

Other common additives, like soy and corn, also contribute to water pollution. Fortunately, a team of researchers at UC Santa Cruz, led by Pallab Sarker, have developed a fish-free formula that replaces these harmful ingredients with microalgae. Microalgae is abundant, easy to cultivate, and has a low environmental footprint. The team tested their new feed in tilapia farms with great success. Fish fed with algae achieved 58 percent higher weight gain than traditionally-fed counterparts. These fish also had higher concentrations of DHA omega-3, the fatty acid critical for human health.

Farmed fish will continue to play a larger role in human diets as our populations grow. It offers the benefit of having less of an impact on wild populations, but pollution and lower nutritional value in the product make many consumers wary. With algae-based feed, we could cultivate healthier populations for human consumption with a smaller environmental footprint. 

Moving forward, the researchers hope to find a manufacturer for their algae feed to introduce it to the commercial market. They are also working on developing a formula for trout and salmon feed as these species have a more carnivorous diet than tilapia.