Early development of the self-fertilizing mangrove killifish Rivulus marmoratus reared in the laboratory

Abstract

The mangrove killifish Rivulus marmoratus was reared at 25° ± 1°C and 17 ppt salinity from 0 to 100 days after hatching (DAH), and its early development was described by examining growth and morphometric parameters, meristic characters (vertebral and fin-ray counts), bone-cartilage development, and pigmentation. Growth was isometric for preanal length, head length, snout length, body depth, pectoral-fin length, dorsal-fin length, anal-fin length, and caudal-peduncle depth. Negative allometric growth was observed in eye diameter and gape size. Meristic counts (mean ± SD) for vertebrae (34.2 ± 0.4) and dorsal- (8.6 ± 0.5), anal- (11.4 ± 0.5), and caudal-fin rays (30.2 ± 0.8) were complete at 0 DAH (n = 5), whereas pectoral-fin rays and pelvic-fin rays were complete by 30 DAH (14.5 ± 0.4, n = 5) and 60 DAH (4.2 ± 0.8, n = 5). Full ossification of meristic elements proceeded in the following sequence: vertebrae (by 30 DAH), caudal-, dorsal-, and anal-fin rays (by 60 DAH), pectoral-fin rays (between 60 DAH and 100 DAH), and pelvic-fin rays (by 100 DAH). Both morphological characters and meristic counts indicate that this species can be considered to be a juvenile after 9.8 mm in standard length (20 DAH).