Morphology of gills of the seawater fish Cathorops spixii (Agassiz) (Ariidae) by scanning and transmission electron microscopy

Gills of the seawater fi sh Cat/w raps spixii (Agassiz, 1829) were submitted to routine processing for observation in scanning and transmission electron microscopy. The wrinkled surface of the gill filaments showed well-defined cellular ultrastructures. Microridges on cellular surface were projected over all gi ll structures, including respiratory lamellae. Chloride cells were usually at primary lamellae. Some rod let cells were fo und. Mucous secretory cells were uncommon at all parts of the gill arches. The pharyngeal region of the gill arches showed a lot oftaste buds but no spines. There were smal l and strong rakers. Such morphology is indicati ve of fishes that swallow small food but do not have filtering habits. At the ultrastructural level the gills of C. spixii presented the typical morphological pattern of Teleostei fishes.