Swim bladder inflation as a possible cause of saddleback-like syndrome malformation in hatchery-reared red spotted grouper Epinephelus akaara

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

“…Meanwhile, it has been suggested that an over‐inflated swim bladder could be a cause of vertebral deformities, such as kyphosis, found near the cranial region in Atlantic cod ( Gadus morhua ; Grotmol et al, ) and dusky grouper ( E. marginatus ) (Boglione et al, ). In addition, it has also been suggested that an inflated swim bladder could be a cause of saddleback‐like syndrome positioned in the occipital region in red‐spotted grouper (Iwasaki et al, ). In the present study, kyphosis was not observed near the cranial region, but other deformities, including saddleback‐like syndrome, were observed in the occipital region to a small degree (Figure ).…”

“…Saddleback‐like syndrome has been frequently observed in red‐spotted grouper, but the occurrence positions of saddleback‐like syndrome differed between the two relative fish species that is it mainly occurred in the mid‐dorsal region and the occipital region in longtooth grouper and red‐spotted grouper respectively (Iwasaki et al, ; Setiadi & Tsumura, ). This fact is very interesting, and it might mean that the causes of saddleback‐like syndrome are different between grouper species and that the deformity could be induced several causes.…”

“…Lordosis and kyphosis are conditions of spinal curvature, wherein the vertebral column assumes a V or reverse‐V shape respectively. Saddleback‐like syndrome was recognized as a V‐shaped dorsal‐profile depression, accompanied by deformities and misalignments of the neural spines (NS) of the vertebrae and the pterygiophores of the dorsal fin but without any missing fin elements (Iwasaki et al, ). Vertebral fusion was defined as fused plural neighbouring centra with the plural pairs of NS and haemal spines (HS).…”

“…Some information is available on the skeletal development of the dorsal‐ and pelvic‐fin spines of longtooth grouper (Sawada et al, ), but there is no published information on the osteological development of the vertebral column, caudal‐fin skeleton or dorsal‐fin supports. Furthermore, it is well known that swim bladder inflation can strongly influence the occurrence of deformities such as spinal curvature (i.e., lordosis or kyphosis) and saddleback‐like syndrome in many fish species, including groupers (Boglione et al, ; Chatain, ; Grotmol, Kryvi, & Totland, ; Hayashida, Tsukashima, Matsukiyo, & Kitajima, ; Iwasaki, Teruya, Mizuta, & Hamasaki, ; Jacquemond, ; Kitajima, ; Kitajima, Tsukashima, Fujita, Watanabe, & Yone, ; Nagano et al, ; Tsuji et al, ; Uji, ). Hence, the influence of swim bladder inflation on deformities in longtooth grouper should be studied.…”