(A) Medaka at stage 43 (body length of 18 mm) double-stained with alcian blue (cartilage) and alizarin red (bone). (B) Newly hatched medaka larva at stage 40. (C) A caudal fin in an adult medaka (3 months old; stage 44). Anterior is to the left and dorsal is up. a, anal fin; c, caudal fin; d, dorsal fin; m, membranous fin; pec, pectoral fin; pel, pelvic fin.