A PhD thesis by Hooi Ling Khaw investigated genetic and environmental interactions in Nile tilapia, and their effects on growth rate and body weight.
Tilapia is the most widely cultured aquaculture species in the world, and Nile tilapia accounts for around 70 per cent of the global tilapia production.
Tilapia are produced both in cage and pond systems, which may mean that different genotypes respond to environments in different ways.
However, the genetic correlation between body weight and size in both systems is high, so that a single breeding program can be used for both production systems.
The research also demonstrates that tilapia show competitive interactions, which have a genetic background.
Those social effects contribute substantially to heritable variation in body weight, with greater competition generally corresponding with greater variation among individuals.
This indicates that breeders could improve growth rate by breeding fish that are less competitive.
Other results of the study show that body weight uniformity in tilapia has substantial genetic variation, but this variation seems unrelated to competition among individuals. Thus uniformity can be improved by genetic selection, but this does not necessarily lead to cooperative fish.
