The stocking of western mosquitofish (Gambusia affinis) to control mosquitos has been shown to negatively impact native fishes, especially species with similar ecological requirements such as topminnows. As a result, using fish species (e.g., blackstripe topminnow; Fundulus notatus) that are native and rarely exhibit aggressive behaviors toward ecological equivalents may serve as a non-intrusive means of mosquito control. In this study, a series of laboratory microcosm experiments were used to examine intra- and interspecific agonistic behavioral interactions (e.g., chases and nips) between blackstripe topminnow and northern starhead topminnow (Fundulus dispar), northern studfish (F. catenatus), and banded killifish (F. diaphanus) at three different fish density combinations and in the presence or absence of vegetation. Few agonistic behaviors were exhibited toward conspecifics, but interspecific chasing and nipping did occur, albeit it at low levels, in the presence of blackstripe topminnow. The number of these interspecific chases and nips was not influenced by vegetation or topminnow species density. Fin damage incurred by topminnows was minimal, regardless if tanks contained only individuals of the same species or another species (blackstripe topminnow). Three percent of blackstripe topminnows had damage to their caudal fins that was intraspecific in nature, but there was no fin damage for the other three topminnow species. Based on these results, we suggest that blackstripe topminnow be considered as an alternative to western mosquitofish for mosquito control in drainages for which it is a native species.
