Economic and Environmental Impacts of Improving Growth Rate and Feed Efficiency in Fish Farming Depend on Nitrogen and Density Limitation

The aim of fish breeding is to increase profit by producing faster growing fish with lower feed intake. However, little is known about the economic and environmental impacts of selective breeding programs for fish. We modelled a fish farm producing African catfish in a Recirculating Aquaculture System (RAS) to calculate economic values of growth rate and feed efficiency with production limited by fish density in rearing tanks and fish nitrogen emission. We also calculated “environmental values” with Life Cycle Assessment. The economic and environmental values of growth rate and feed efficiency depended on the limiting factor. When nitrogen was the limiting factor, economic and environmental values of growth rate were zero. But, on the other hand, feed efficiency always had positive economic and environmental values. Therefore, fish breeders may need to adapt their breeding objectives according to the limiting factor.