Catfish genus can be defined as fish that displays an eel (snake) shape, having an elongated cylindrical body with dorsal and anal fins being extremely long (nearly reaching or reaching the caudal fin) both fins containing only soft fin rays The outer pectoral ray is in the form of a spine and the pelvic fin normally has six soft trays. The head is flattened, highly ossified, the skull bones (above and on the sides) forming a casqued and the body is covered with a smooth scale less skin.
The skin is generally darkly pigmented on the dorsal and lateral parts of the body. The color is uniform marbled and changes from grayish olive to blackish according to the substrate. On exposure to light skin the color generally becomes lighter.They have four pairs of unbranched barbels, one nasal, one maxillar (longest and most mobile) on thevomer and two mandibulars (inner and outer) on the jaw. Tooth plates are present on the jaws as well as on the vomer. The major function of the barbells is prey detection. A supra-branchial or accessory respiratory organ, composed of a paired pear-shaped air-chamber containing two arborescent structures is generally present. These arborescent or cauliflower-like structures located on the secondhand forth brachial arcs, are supported by cartilage and covered by highly vascularised tissue which can absorb oxygen from atmospheric air (Moussa, 1956).
The air chamber communicates with the pharynx and with the gill chamber.The accessory air breathing organ allows the fish to survive for many hours out of the water or for many weeks in muddy marshes.
Written by :Gertjan DE GRAAF and Johannes JANSSEN NEFISCO FOUNDATIONAMSTERDAM, THE NETHERLANDS
Figure 3: Morphological characteristics of C. gariepinus.
4. Sexual Characteristics The male and females of C. gariepinus can be easily recognized as the male has a distinct sexual papilla, located just behind the anus. This sexual papilla is absent in females
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