Skeletal development and deformities in cultured larval and juvenile seven-band grouper, Epinephelus septemfasciatus (Thunberg) Naoki Nagano 1à , Akiko Hozawa 1 ,Wataru Fujiki 1 ,ToshiyukiYamada 2 , Kadoo Miyaki 2 ,Yoshitaka Sakakura 3 & Atsushi Hagiwara 4 1 Nagasaki Industrial Promotion Foundation, Nagasaki Prefectural Institute of Fisheries, Nagasaki, Japan 2 Larval Rearing Centre, Nagasaki Prefectural Institute of Fisheries, Nagasaki, Japan 3 Faculty of Fisheries, Nagasaki University, Nagasaki, Japan 4 Graduate School of Science and Technology, Nagasaki University, Nagasaki, Japan Correspondence: N Nagano, Faculty of Agriculture, Miyazaki University, 1-1 Gakuen-kibanadai-nishi, Miyazaki, 889-2192, Japan. E-mail: n-nagano@cc.miyazaki-u.ac.jp à Present address: Faculty of Agriculture, Miyazaki University,1-1 Gakuen-kibanadai-nishi, Miyazaki,889-2192, Japan. Abstract The seven-band grouper, Epinephelus septemfasciatus (Thunberg), is currently recognized as a potential new species for aquaculture in Japan. This study de- scribes normal and abnormal skeletal development of the jaw and vertebrae in cultured larvae and early ju- veniles of E. septemfasciatus. The ontogenetic stages at which skeletal deformities of jaw and vertebra developed were also described for this species. Osteo- logical observations were made using a clearing and staining method for larvae and soft X-ray photo- graphs for juveniles. A high incidence of skeletal deformities was observed in the jaws and vertebral column during the larval and juvenile stages. Most of the jaw deformities were explained by an abnormal maxilla curvature. Jaw deformities were visually evident from £exion stage after ossi¢cation of the deformed elements. Deformities in the vertebral col- umn (mostly lordosis) were observed from the post- larval stage and became more evident as growth proceeded. The lordosis generally occurred on the positions of the 8^11th vertebra. These types of defor- mities are compared with those of other species, and possible causative factors of the skeletal deformities are discussed. Keywords: seven-band grouper, larval rearing, jaw deformity, vertebral column deformity Introduction Skeletal deformities in reared ¢sh are a major con- cern in aquaculture and have been described for many ¢sh species (reviewed by Divanach, Boglione, Menu, Koumoundouros, Kentouri & Cataudella 1996; Gavaia, Dinis & Cancela 2002; Cahu, Zamboni- no Infante & Takeuchi 2003). Most of the skeletal deformities include jaw, operculum, spinal (lordosis, kyphosis, scoliosis and vertebrae fusion) and ¢n mal- formations. Deformities in the juvenile stage have a direct impact on commercial aquaculture, as they re- duce the market value of ¢sh products and require manual sorting. So far, early detection and sorting of the deformed ¢sh is the only feasible option for management in commercial hatcheries. Groupers (family Serranidae, subfamily Epinephe- linae) are one of the most commercially important marine ¢sh in coastal ¢sheries of tropical and subtro- pical seas. Although many attempts have been made to rear larval grouper, high mortality in the early stages and the occurrence of skeletal deformities are critical problems (Sugama & Ikenoue 1999; Song, Oh, Seo, Ji, Lim, Lee & Kim 2005). Cultured long tooth grouper, Epinephelus bruneus Bloch, presented mal- formations of 49.5% in the population (Song et al . 2005). The seven-band grouper, E. septemfasciatus (Thunberg), has been recognized as a potential new species for aquaculture in Japan and is a commer- cially important species. It reaches up to 90 cm in Aquaculture Research, 2007, 38, 121^130 doi: 10.1111/j.1365-2109.2006.01627.x r 2007 The Authors Journal Compilation r 2007 Blackwell Publishing Ltd 121