Hybridisation and subsequent introgression threaten many species world-wide through the loss of genetic and species diversity. The Running River rainbowfish is one such species. As multiple species of Melanotaenia are threatened by introgressive hybridisation with Melanotaenia splendida we decided to investigate the factors influencing hybridisation with M. splendida. This was achieved through the use of mate selection and cross-breeding experiments. Here we present the bulk of our findings.