Hypostomus punctatus was collected between June/1987 and July/1988, in three sampling stations with different features, along the Ubatiba stream (Maricá, Rio de Janeiro state). Sampling stations 2 and 3 were more similar (50% similarity) to each other. The species was frequent and persistent in all sampling stations. The size varied from 1.0 to 22.2 cm. The occurrence of different size classes along the stream was probably related to the kind of environment. Young forms prevailed in the total sample and were mainly collected next to the submersed riparian vegetation. Adults occurred just in sampling stations 1 and 2, and were found most often in rapids with rocky bottom, and in pools among submersed branches.
fish; Hypostomus punctatus; longitudinal distribution; structure in size; coastal streams
