The functional significance of egg-spots in the maternal mouthbrooder
Pseudotropheus aurora Burgess 1976, has been examined in the field. Egg-spots
are conspicuous orange spots on the anal fin of males which are believed to mimic
eggs and function both to attract females and to ensure fertilization. The egg-spots
of Astatotilapia elegans (Trewavas, 1933) are male sexual signals that attract
females and stimulate them to spawn but do not increase fertilization rates. The
present work seeks to establish whether this finding is transferable to the field
and to another species. A pilot experiment in the laboratory suggested that female
choice of males is based on numbers of spots. In the field, experiments tested which
male would stimulate the females to spawn more frequently. The field experiments were
undertaken off Thumbi Island West in the southern part of Lake Malawi where
P. aurora was introduced about 20 years ago.