When subjected to increasing sulfide concentrations,
under normoxic conditions, the lethal limit of tamoata´ was
about 70 AM of this compound (Fig. 2a). However, under
hypoxic conditions the lethal limit rose to 87 AM (Fig. 2b).
This increase in the sulfide tolerance may be attributed to
the air-breathing behavior of the species, which can be
confirmed by the analysis of Fig. 3a and b. When exposed to
different sulfide concentrations and under normoxia, the
aerial respiration of tamoata´ increased significantly at a
sulfide concentration of 15 AM (Fig. 3a). However, hypoxia
induced aerial respiration (Fig. 3b) and fish displayed
significantly higher fRA at a sulfide concentration of 3
AM. Since high sulfide concentrations are always associated
with environmental hypoxia, this last situation simulates the
natural conditions where tamoata´ occur.