| Abstract: | Aggression in the convict cichlid Cichlasoma nigrofasciatum was measured under two different environmental parameters after introduction of a conspecific intruder. Measurements were made after 24-hr and 48-hr teritorial residence times at both 26°C and 30°C. Eight fish established territories in individual tanks each containing one terra cotta pot. Intruders contained in a glass cylinder were introduced into the territories. An opaque divider separating the resident from the intruder was removed after a 15-min acclimation period. At 26°C, we observed a significant difference in the mean number of bites of the cichlids of 24-hr and 48-hr residency durations, whereas, at 30°C, such a difference did not exist. Statistical analysis showed that cichlids exhibited more aggression at 30°C than at 26°C. Increased aggression levels at the higher temperature may be related to the fact that cichlids establish territories and spawn at about 30°C. |
