There is an increasing problem with bacterial disease associated with stress in farmed frogs. In general, little is known about the immune system in farmed tropical ranid species and, in particular, about its functional ability. As part of a study on the non-specific immune system, immunostimulation by β-glucan was evaluated in preventing bacterial disease in cultured ranid frogs. Fifty frogs were grown to a mean weight of 40 g and separated into three experimental groups. These were exposed to a motile aeromonad bacterial challenge alone (Au), bacterial challenge with β‐glucan (Au + glucan) or saline only (controls) to serve as controls. There were four replicate tanks containing five frogs per tank in each experimental group. After bacterial challenge, all the animals were observed twice daily, and the number of mortalities per tank was recorded. The liver was sampled in order to recover bacteria, and any colonies grown were identified. The survival of the β‐glucan-treated frogs was significantly higher than that of the bacterial challenge group alone.