The present paper is the first part of the catalogue of marine fishes belonging to the collection of the Laboratory of Ichthyology (Universidade Federal do Rio de Janeiro-RJ) to be published. Here are included Chondrichthyes (Rajiformes) and part of Osteichthyes, Teleostei (Elopiformes to Dactylopteriformes) in a total amount of 30 families, 52 genera and 62 species. The most part of the material have been collected at the littoral of the State of Rio de Janeiro. For each species considered is given the vulgar name (when known in Southeastern Brazil), the known distribution (in Western Atlantic Ocean) and some data as collecting locality, total number of collected specimens and the register number in the collection. Scorpaena isthmensis Meek & Hildebrand, 1928 (Scorpaenidae) is for the first time mentioned for the Southern littoral of Brazil.