Female (A–E) and Male (F–L) medaka (d-rR strain). The shape of the dorsal fin differs between the sexes (B, female; G, male). The posterior margin of the male dorsal fin has a cleft (G, arrow). The shape of the anal fin differs between the sexes (C, female; H, male). The female anal fin rays are bifurcated (C, inset). The urogenital papillae are prominent in the female (D, arrow; E, dotted line) but less developed in the male (K, L). The male anal fin has papillar processes on the posterior portion (I, J). Scale bar, 5.0 mm.