Radiographic studies on morphological anomalies in artificially spawned Heterobranchus longifilis Valenciennes, 1840 F1 generation
This study was designed to examine radiographically the morphological anomalies in artificially spawned 24-week-old Heterobranchus longifilis. A total of 22 morphological deformities observed from an F1 population of 4,871 were classified. Based on anatomical positions, most of the anomalies (49.99%) manifested in the bodies as stunted growth with a weight range of 240-358g, standard length (SL) of 18.7-29.1cm and stump body trait with a weight range of 445-810g, SL of 22.9-35.9cm. Anomalies of the vertebral column accounted for 27.27% with a weight range of 410-945g, SL of 27.4-36.8cm. Fin aberrations including agenesis were seen in 22.73% with a weight range of 548-840g, SL of 34.1-39.2cm. Radiographic examination revealed anomalies such as hypoplasia and hyperplasia of fins, supernumeracry and agenesis of fins, fin cleft, and fusion of fins, scoliosis and kyphosis. The phenotypic lateral body curvatures and stump body trait were basically due to varying degrees and positions of scoliosis and thus, pathological. The fin aberrations and agenesis were probably congenital. The anomalies affected feed accessibility; thus; impaired the growth of the fishes evidenced by the low body weights recorded in the deformed fish compared to the normal fish. In conclusion, the percentage of morphological aberrations observed in the F1 population is negligible (0.45%), thus it will not adversely affect production of H. longifilis via artificial induction.
Keywords: Artificial induction, Heterobranchus longifilis, Morphological anomalies, Radiography