Observation on the reproductive behavior and embryo of the daisy’s ricefish, Oryzias woworae in laboratory condition

Abstract

Oryzias woworae is an endemic ricefish from Muna Island, Southeast Sulawesi, traded as an ornamental fish. Information on the biology of these fish is very lacking, including their reproductive. These fish also face the threat of population decreasing in the wild. The research aimed to examine the spawning behavior and embryonic of O. woworae as the basis for aquaculture. Fish spawning was carried out using 1 male: 1 female ratio, which was repeated three times. The observed spawning behavior was pre-spawning, mating process, egg number, and morphology. Behavioral observations were carried out for five days of spawning. Observation of embryos was carried out to see the stages of embryo development until hatching. The results obtained on pre-spawning behavior were changes in body color and blackened fins in males, which did not occur in female fish. Males actively swim by approaching their dorsal and anal fins while chasing females. The female releases the eggs and is attached to the substrate, rapidly fertilized by the male fish. There is a phenomenon of females carrying eggs on the genital pore before being released to the substrate (non-pelvic brooder). Spawning only occurs during the day, and spawning is getting faster, which is at 09:00 AM on the fifth day. Oryzias woworae eggs have a diameter of 1.3 ± 0.2 mm, equipped with attaching and non-attaching filaments. Observations of O. woworae embryos showed that embryo hatching occurred at seven days 23 hours post-fertilization.