Researchers from the Seaweed Research Group of the University of the Sunshine Coast in Australia found that feeding rabbitfish with a seaweed called Ulva in small doses could significantly enhance the fishes’ immune response.

The objective of the study was to boost the immune system of fish, so they don’t require treatment down the track. Researchers dried and powered the seaweed and used a standard blender to mix it with water and a commercially-available fish feed at a rate of just two percent of the feed. The feed was dried again into pellets.

“The seaweed can either be recognized by the fish’s immune system or indirectly by modifying the gut microbiome of the fish which, in turn, has a positive effect on the innate immune system of the fish. We found that we could double the immune response in the fish that were treated with seaweed, compared to the non-treated fish,” said Valentin Thépot, Ph.D. candidate.

Associate Professor Nicholas Paul said that disease is a major limiting factor for aquaculture, costing the industry up to $6 billion each year, a threat currently tackled largely through antibiotic use. “Promoting the immune system of the fish in a natural organic or natural way, rather than with chemicals, is ultimately better for the environment and for us.” He said that preliminary results like this are feeding confidence to build new industry around farming seaweed.  “There are 10,000 different species of seaweed in the world and they all have different properties that can be used for various applications, and we are actually finding some really high-value ones like this,” Paul said.