Mated pairs of convict cichlidsCichlasoma nigrofasciatumwere exposed to one of two acidities (pH 5.0–5.5 and pH 7.0) and allowed to breed. Two conspecifics similar in size to the parents were placed in the tank to act as objects of parental aggression. These conspecifics were isolated from the parents by a grid barrier that allowed free visual and chemical interchange between conspecifics and parents. Significant alterations in brooding behaviors and aggressive activities occurred in pairs exposed to pH 5.0–5.5 compared to those at pH 7.0. Females reduced brooding behaviors at lower pH and males increased brooding behaviors to compensate for reductions by females. Aggressive behaviors, especially by males, increased under low-pH stress. Increased visual aggression may reduce the need for physical altercation in stressed environments.