Idaho is the largest producer of commercial rainbow trout in the U.S. and the University of Idaho’s Aquaculture Research Institute (ARI) is charged with finding ways to improve the industry.

One problem the Idaho aquaculture industry faces is the presence of excess iron in the groundwater, assistant professor Vikas Kumar said. In one of ARI’s many projects, Kumar studied the mitigation of iron toxicity in catfish. Working in collaboration with the University of Arkansas, the team found feeding catfish vitamin C can alleviate the negative effects of too much iron in the water.

“We cannot buy the filter to remove the iron because if we were to buy the filter to grow fish, we would spend millions of dollars to clean the water,” Kumar said. “That’s almost impossible. So, what we did is ask what we could do to the nutrition of the fish.”

Kumar and his fellow researchers also found feeding trout bentonite, a type of natural clay, relieved stunted growth caused by iron toxicity. Kumar said the bentonite binds with the iron molecules, making it indigestible and it is discarded in the fish waste.