Abstract
Adipose fins of 33 species belonging to the Salmoniformes, Cypriniformes, Siluriformes and Myctophiformes were studied. Cartilaginous structure was found in the base of the adipose fin in 14 species of the Salangidae, Osmeridae, Plecoglossidae, Myctophidae and Neoscopelidae.In the Osmeridae, the cartilaginous structure can be divided into two types: a rather large slender cartilage observed in Spirinchus, and a small pear-shaped cartilaginous structure observed in Thaleichthys, Osmerus and Hypomesus. The former is similar to that of the Salangidae. The latter is similar to the cartilage of the Plecoglossidae in shape and location. In the Myctophidae and Neoscopelidae, cartilage and chondroid tissue are ventrally inserted in the underlying muscle layer, and different from the cartilaginous structure found in three families of the Salmoniformes in morphological characters.
As far as it was observed, no cartilaginous structure was detected in the adipose fin of fishes belonging to the families Salmonidae, Retropinnidae, Prototroctidae, Aulopodidae, Synodontidae and Chlorophthalmidae, suborders Argentinoidei and Characoidei, and the order Siluriformes.
