Osteological development and deformities in hatchery‐reared longtooth grouper (Epinephelus bruneus): Vertebral column, dorsal‐fin supports and caudal‐fin skeleton

Skeletal deformities are one of the serious problems in hatchery‐reared longtooth grouper (Epinephelus bruneus). In this study, seed production of longtooth grouper was carried out in four large hatchery‐grade tanks. Osteological development of the vertebral column, caudal‐fin skeleton and dorsal‐fin supports in larvae and juveniles was described. The vertebral ontogeny started at 4.8 mm total length (TL) with the formation of neural spines 2 and 3, and the vertebral centra began forming at 5.3 mm TL. By 16 mm TL, all vertebral bony elements were formed except for the dorsal ribs. The onsets of the ontogeny of the caudal‐fin skeleton and dorsal‐fin supports occurred at approximately 5.1 mm and 3.9 mm TL, respectively, and the completion of these bony elements occurred at approximately 20 mm TL. The incidence of deformity was examined; some type of deformity was observed in 57%–68% of the specimens. These deformities mainly occurred as three types: lordosis, around vertebrae 1–5; saddleback‐like syndrome, around vertebrae 7–11; and vertebrae fusion, around vertebrae 22–24. The incidence of prehaemal lordosis was significantly higher among individuals with an uninflated swim bladder than among those with an inflated swim bladder.