Swimbladder and skeletal deformations in hatchery bred Spams aurata

Among hatchery bred Sparus aurata, 5.4% of the offspring of a single parent pair showed severe skeletal deformations coupled with marked growth retardation and pathological changes in the swimbladder. This resulted from extreme proliferation, then hypertrophy, of the cuboidal epithelial cells of the gas gland and proliferation of the rete mirabile. This caused almost complete congestion of the swimbladder air space. The nature of the pathological changes in the swimbladder and the possibility of hereditary origin for both the skeletal and swimbladder deformations are discussed.