A TEAM of researchers in the United States may have overcome one of the main environmental criticisms connected with fish farming.

The researchers from the Institute of Marine and Environmental Technology in Baltimore have announced that they have developed a plant-based diet for three popular saltwater fish — striped bass, cobia and Mediterranean sea bream. Taste-testers can’t tell the difference between fish raised on the plant-based diet (vegetarian) and those raised on fish meal, they say.

Both diets contain fish oil, so neither was totally fish-free, but the researchers also raised fish on a vegetarian diet using wheat, corn, soy and algae meal to replace the oil. That raises the possibility of fish-free aquaculture for saltwater, carnivorous fish, said Aaron Watson, a graduate student at the institute.

The Baltimore Centre is a highly respected institution which looks at many aspects of marine environmental sustainability involving people and natural resources. One of its aims is to help reduce the environmental impact of fishing and fish farming. It even has its own fishing research fleet.

US President Barak Obama has already give to the go-ahead for a major growth in his country’s aquaculture plans and Mr Watson added: “If we wish to get aquaculture to expand, we need to find alternatives.”

American nutritionists are constantly urging people to eat at least two fish meals a week for good heart health, but many are worried about some of the environmental concerns surrounding fish farming – witness the debate in British Columbia, Canada. It is hoped that the results of the Baltimore research will help overcome some of those concerns.

Mr Watson said that the tests showed that a plant and algae diet had a same levels of heart-healthy fats as a fish based diet which should give more confidence to consumers.