2. Materials and methods
2.1. Facilities and O. niloticus broodstock
All mate choice trials were carried out in the tropical aquarium
facilities of the Institute of Aquaculture, University of Stirling. The
adult fish used in this study (homozygous wild type or homozygous
red: McAndrewet al., 1988)were bred fromstocksmaintained in the
facilities. Trialswere carried out in a circular arena tank (radius=1.05 m;
height=0.50 m; volume=1.73 m3; flow rate=4.14 l/min) in a recirculating
system at 27 °C. Fish were fed twice a day with trout pellets
(Skretting, UK). All adult fish were PIT-tagged (Passive Integrated
Transponder) for identification and a fin biopsy was removed from the
soft-rayed part of the dorsal fin and preserved in 95% ethanol for DNA