Some Aspects on the Anatomy and Histology of the Alimentary Canal of Hydrocyon lineatus, White Nile, Sudan

The present study is an attempt to describe the gross anatomy and histology of the alimentary canal of the economically important Nile fish, Hydrocyon lineatus, which is exclusively a carnivorous fish. The genus Hydrocyan is a member of the family Characidae. The family Characidae is a very generalized group confined to the fresh waters of Africa and South America. The species number about 500, of which only one-fifth are African. Of the twenty African genera only eight are represented in the Nile system. Living specimens of Hydrocyon lineatus were used during this work to study some aspects of the anatomy and histology of the alimentary canal. The general organization and structure of the different layers was found to confirm to the case found in general chordate organization. Nonetheless, it was thought pertinent to conclude that similarity in structure of the caeca to that of the intestine would justify replacement of the old nomenclature from pyloric caeca to intestinal caeca. Again, the presence of an intestinal mucosal fold could possibly be a characteristic diagnostic feature of the group in as much as it could be pleisiomorphic characteristic only occurring in lower groups of chordates.