A unique adhesion apparatus on the eggs of the catfish Clarias gariepinus (Teleostei, Clariidae)

Eggs of the catfish Clarias gariepinus were investigated for the first time using light and electron microscopy (SEM and TEM). In shape, they differ strongly from those of other teleosts, their characteristic profile resembling a fur cap. This shape is unique among the eggs of teleostean fishes. The eggs of C. gariepinus are attached to substrata at their animal pole, which shows an annular bulge consisting of numerous tiny attaching-filaments. These filaments seem to be a part of the zona radiata externa. The micropyle, located within the center of the annular bulge, is a straight opening in the zona radiata. Different ways of egg adhesion in teleosts were compared and discussed as well as the position of the micropyle with respect to fertilization.