1. The air-breathing behaviour of Hoplosternum thoracatum and Brochis splendens has been studied and their strategy of coordinating the respiratory and hydrostatic functions of the accessory respiratory organ has been examined. 2. H. thoracatum and B. splendens are continuous but not obligate air-breathers and individuals of the former breathe air in synchrony with each other. 3. Frequency of a...

Exposure of a facultative air breather, Hoplosternum littorale, to 12.5, 25, and 37.5% of the water soluble fraction (WSF) of Urucu crude oil, resulted in a rapid increase in air-breathing frequency (ABF) sustained over the 45 min period of exposure. Following 4 h exposure to a graded increase in WSF up to 50%, there was no significant affect on haematocrit, or plasma [Na+] and [K+]. Crude oil ...

Two new species of Henneguya (Myxozoa) were described from specimens collected on the gills of Hoplosternum littorale (Hancock, 1828) (Callichthyidae) and Cyphocharax gilbert (Quoy and Gaimard, 1824) (Curimatidae), from Guandu River, State of Rio de Janeiro, Brazil. The species described were compared with the related species of the genus. The new species of Henneguya parasitic on H. littorale ...

Sensitivity to acid water was assessed in three species of Amazonian fish that encounter naturally acidic blackwaters to differing degrees in the wild: tambaqui (Colossoma macropomum), matrincha (Brycon erythropterum), and tamoatá (Hoplosternum littorale), in decreasing order of occurrence in blackwater. Fish were exposed to a graded reduction in water pH, from pH 6 to 5 to 4 to 3.5, followed b...