Dimensions, micromorphology, microanatomy and cytochemistry of the gills of a swamp catfish,Chaca chaca have been investigated using morphometric, scanning electron microscopic, light microscopic and cytochemical techniques respectively. The findings have been correlated with the respiratory efficacy of the gill sieve and the physicochemical behaviour of the habitat of the fish.
The filament number among 4 gill arches varies from 144–151 and does not show any significant (P>0·05) difference among themselves. The filament length shows heterogeneity in their relative dimensions at different points along the various hemibranchs of the 4 gills. Lamellar frequency (n) and area (bl) were 31·2 and 0·08316 mm2 respectively. The small gill area (13905·3 mm2) assigns comparatively low level of activity to the catfish. Total lamellar water flow of the gill sieve ofChaca was 20·123 cc/s.
The heterogenous gill arch epithelium contained taste buds and mucous gland openings. Short and stumpy gill rakers signify carnivorous feeding habit of the catfish. The micropockets of the gill filament epithelium entrap some water molecules to protect the gills from desiccation, when the fish is temporarily exposed to water-land interface and acts as a regular source of oxygen to the fish during adverse ecological conditions.