The present work presents a part of the series of studies designed to find out how far the oesophagus and stomach of the characinid fish Alestes dentex Gunther &Trosehel 1854, morphologically and histochemically, are adapted with the peculiar carnivorous habit. The general histology, the tunics, with their arrangement and their constituents, tissues, and transition from one region to another are given detailed treatment. The reaction of the different portions to the various histochemical tests receives particular stress. Results revealed that the oesophagus is a short distensible
tube; grossly divisible into cranial and caudal portions. The basic layers making up the wall of the oesophagus are mucosa, submucosa, muscularis and serosa. The mucosa is disposed into primarily longitudinal folds. Small secondary folds are also present at the bases of the crypts. The epithelium is provided with stratified and columnar cells. They contained acid and neutral mucopolysaCcharides (MPS). Toluidine blue (TB) indicating the presence of the purely acid MPS. Tunica propria can easily be detected. Submucosa, of areolar connective tissue is richly supplied with lymphocytes, blood vessels and occasional nerve fibers. Muscularis mucosa is well developed. Taste buds absent.Muscularis externa of one layer, only the circular. Serosa of squamous epithelium,one cell thick. The stomach is of the siphon type, grossly divisible into cardiac, fundic, and pyloric regions. The pyloric region is extremely short and is provided with the pyloric
sphincter. The mucosa is provided with highly primary rugae. The latter are subdivided mostly into a network of secondary ones.