The Biology and Culture of Tilapias

and "stump body" (Plate 3). "Saddle back" fish lack all or part of the dorsal

fin and in extreme cases, some or all of the pectoral, pelvic and anal fins also.

Such fish were, from his studies, also less resistant to diseases such as Sapro-

legnia fungus infection. In the "stump body" the body is compressed antero-

posteriorly, with no two fish showing the same skeletal anomaly. The

saddle back form has not been described elsewhere than in the Auburn fish

and it is the stump body anomaly that is the one which is widely observed.

Plate 3a. Normal Sarotherodon aureus radiograph.

Plate 3b. Fish showing the saddle back spinal deformities (arrowed) and dorsal fin anomaly.
(From material kindly supplied by Dr. D. Tave).