Abstract:
Freshwater fishes in Sri Lanka is a diverse group and one of the major components for its diversity richness allied with high degree of endemism. Aplocheilus dayi is one of the nationally
threatened endemic fish species in Sri Lanka confined to very limited locations. Despite their
economic, conservation and scientific importance to date, there are very limited information
available on the extent of its reproductive biology and breeding performances. Hence, a preliminary study was designed to gather the fundamental information on the reproductive biology
and captive breeding of A. dayi. Morphological characters including body coloration, fin shapes
were used for sex determination. Maximum observed total length in A. dayi was 60 ± 1mm and
50 ± 1mm for males and females respectively. Male is more colourful and presence of red
colour stripe in the caudal fin, 3–4 black spots in the abdominal area and pointed fins are some
prominent characters. In contrast female is less colourful, having 6–7 horizontal black colour
stripes together with black spotted rounded caudal and dorsal fins. Breeding experiment was
arranged in glass tanks (L-18” x W-10” x H-10” and water depth = 10cm) using different sex
combinations i.e male: female 1:1, 1:2 and 1:3 along with alternative substrates i.e. aquatic
plants, Sand and Acrylic yarn mop. It was assumed that the water quality changers were insignificant throughout the experimental period. According to the results highest spawning was
recorded in 1 male: 2 female combination with 12–13 eggs/day where the Acrylic yarn mop
used as the substrate. However, pair breeding was unsuccessful and egg eating behaviour was
also observed in the tanks where 03 females used. During the experimental period different
feed types including commercial pelleted feeds and live feeds such as daphnia, mosquito larvae, bread worms, black solider fly larvae and Artemia were used. However, it seems that fish
more interested on live feeds especially the mosquito larvae since fish fed with mosquito larvae
had the highest egg laying percentage. The eggs were hatched using water incubation technique
and the hatching time extended up to 12–14 days claiming the slow metabolism which is a characteristic feature of killifish species.
