Preference in water depth for egg deposition of female medaka, Oryzias latipes.

Abstract

The present study examined the preference in water depth for egg deposition of female, orangered variety medaka Oryzias latipes in order to obtain basic information for conservation of wild medaka. Substrates for egg deposition were set at various depths in experimental aquaria and male and female medaka were kept in the aquaria for seven days to observe spawning. The number of eggs and the egg deposition depth were recorded every day. The female medaka deposited eggs on the substrates at various depths but notably a significantly large number of eggs were deposited at shallow depths. These results indicate that female medaka gives a preference to shallow water depths for egg deposition.