RESPIRATORY RESPONSES TO HYPOXIA IN RELATION TO MODE OF LIFE OF 2 ERYTHRINID SPECIES (HOPLIAS-MALABARICUS AND HOPLIAS-LACERDAE)

Predominantly, Hoplias malabaricus inhabits stagnant O2 poor environments, whereas Hoplias lacerdae occurs in well‐aerated streams. The present study evaluates the influence of mode of life on O2 uptake and gill ventilation in equally‐sized (300 g) specimens of this genus at 25° C. Comparing the species, H. lacerdae was characterized by the highest O2 uptake and gill ventilation combined with a relatively higher cost of breathing and a lower O2 extraction. Both species substantially increased ventilation in response to hypoxia with the difference that H. malabaricus exclusively augmented tidal volume, whereas H. lacerdae also increased breathing frequency. Copyright © 1992, Wiley Blackwell. All rights reserved