And the fitness of these fish is hereditary, report Wageningen researchers in Scientific Reports.
The researchers put the fish through a swimming test in which the tilapia had to swim against a current while the researchers gradually increased the strength of the current to measure the fish’s fitness level. Researchers Samuel Mengistu found that the fish that swum faster grew more slowly. His co-supervisor, Arjen Palstra from Breeding and Genomics, thinks an old evolutionary principle is behind this: to escape its enemies, the fish either needs to grow faster or to swim faster.
The researchers have evidence that the faster fish are also more resistant to diseases. So they advise tilapia farmers to use the swimming test in their breeding programmes. Up to now, breeders tend to select primarily for fast growth. Now that the water the fish live in is warming up and the pressure of disease is increasing, a healthy immune system is increasingly important. The Wageningen research team, led by personal professor Hans Komen, is going to do the fitness test with other fish too, such as trout and salmon.