Distribution of suckermouth armoured catfishes (Siluriformes, Loricariidae) across the salinity gradient of the Mekong Delta, Vietnam.
It has been suggested that suckermouth armoured catfishes of the genus Pterygoplichthys Gill, 1858 (Siluriformes: Loricariidae) might use brackish water systems as a means to disperse between freshwater bodies. This study aimed to explore the dynamics of Pterygoplichthys spp. distribution in relation to salinity gradient and provide population characteristic data, namely length, weight, condition factors by sampling the Co Chien and Ham Luong rivers, Mekong Delta, Vietnam. Contrary to initial predictions, there was neither evidence for the presence of Pterygoplichthys spp. in brackish waters in the Mekong Delta nor for the fishes' colonisation of an area that fluctuates seasonally between freshwater and brackish water. Length-weight relationship and condition factor of the fishes demonstrated negative allometric growth and good physiological condition. The findings from this study could help fishery managers to map out the distribution of Pterygoplichthys spp. in the Mekong Delta as well as raise awareness on the perils of releasing aquarium pets.