Breeding and Early Development of an Endemic, Endangered Freshwater Fish <em>Aplocheilus dayi</em> in Captivity

Abstract

Purpose: Aplocheilus dayi (Ceylon Killifish) is a freshwater fish endemic to Sri Lanka, but its conservation has not received much attention as uncontrolled fishing for ornamental purposes and many other human activities have posed significant threats to its survival. Therefore, this study aimed to provide baseline information on the development of a captive breeding system and to study the embryonic and larval development of A. dayi.Research Method: Matured A. dayi fish were acclimatised for two weeks prior to the experiments. A suitable breeding substrate to facilitate successful spawning was identified using two substrates; spawning mop, and sand while no substrate was used as the control. The subsequent breeding experiment (to find the best sex ratio) was performed using different sex combinations (Male: female 1:1, 1:2, 1:3, and 2:4). Subsequently, eggs were collected and analysed for fertility, hatchability, and embryonic development studies.Findings: Spawning mop seemed to be the most preferred spawning substrate for A. dayi. Egg parameters, including fertilisation rate and hatchability, were not significant upon the sex ratios; however, the ratio between male: and female (1:2) had the highest significance (p<0.05) in egg production (4 eggs/day). Moreover, we found that A. dayi eggs showed a lengthy incubation period (11 - 13 days at 25±1 °C), indicating their dormancy nature to bypass the hostile conditions before being hatched.Research Limitations: The breeding pattern under captivity needs to be examined over an extended period in different experimental settings, such as using other culture techniques with varying density ratios.Originality/Value: A. dayi can be successfully bred in captivity, and further this study gives the readers factual information on the embryonic development of A. dayi.