Canonical correspondence analysis (CCA) showing the relationship between species composition and environmental variables across the different sites and the invasion status in the Kowie River catchment. Abbreviations: Anguilla mossambica (AMOS), Clarias gariepinus (CGAR), Coptodon rendalli (CREN), Cyprinus carpio (CCAR), Enteromius anoplus (EANO), Gilchrestella aestuaria (GEST), Glossogobius callidus (GCAL), Lepomis macrochirus (LMAC), Micropterus punctulatus (MPUN), Micropterus salmoides (MSAL), Monodactylus argenteus (MARG), Monodactylus falciformis (MFAL), Myxus capensis (MCAP), Oreochromis mossambicus (OMOS) and Tilapia sparrmanii (TSPA).