Interactions between native and non-native cichlid species in a Costa Rican river

The convict cichlid, Amatitlania siquia, is a serially monogamous, bi-parental cichlid species native to Costa Rican rivers. Numerous field studies conducted in the Rio Cabuyo (Lomas Barbudal, Costa Rica) have provided a wealth of information regarding the behavioral ecology of this species. Recently a cichlid species that was previously not found in the Rio Cabuyo was identified as Hypsophrys nematopus. This influx of this non-native species provides an interesting ability to study the interactions of this potentially invasive species and to monitor the changes made by the native cichlid species. Over the course of several field seasons, I investigated the interactions between the native convict cichlid and the non-native cichlid. I surveyed the distribution of breeding pairs of both species and conducted behavioral tests to examine the interactions between the native and non-native species. I found an overall decline breeding pairs of both species over the course of the study. I found that both species were more aggressive to conspecific intruders and that female convict cichlids were aggressive to juveniles but males were not. These results provide important information concerning how native species interact with non-native species. It appears that the A. siquia population may experience a change in its reproductive behaviors due to the influx of H. nematopus.