The effect of male colouration on reproductive success in Nile tilapia (Oreochromis niloticus)

Abstract

Red tilapia stocks have been developed for aquaculture from rare colour mutations. This study was carried out to discover if male body colour (wild type or red) influences mating success in the Nile tilapia (Oreochromis niloticus), by allowing females to choose between wild type and red males under semi-natural spawning conditions. In a series of eight trials, ten females (wild type females in four trials, red in the other four) were placed in an arena tank with two size-matched males, one wild type and one red. Each trial ran for 5 weeks, during which fish were allowed to spawn and eggs were collected from the mouths of the females after spawning. Paternity was assessed using microsatellite genotyping and phenotype scoring. Where both males contributed to a batch of fry from a single female, the batch was allocated to the "primary" sire for statistical analysis. No significant epartures from equal mating success as the primary sire were observed between red and wild type males. However, there was a significant difference between the red and wild type females in the frequency of secondary paternal contribution to egg batches. These results are discussed with reference to spawning of Nile tilapia in natural and aquaculture environments.