Surgically implanted radio transmitters are useful for monitoring fish behaviour, movement patterns and home range. In Chile, there are no reports using this particular technique in native freshwater fish. Therefore, no standardized protocols have been developed in Chile to describe surgical procedures for inserting the implant nor the required dose of anaesthetics and medications applied to avoid fish mortality. This study describes a procedure for implanting a radio transmitter in Diplomystes camposensis, a native fish of southern Chile, which can be valuable for future research. The procedure was successful on these organisms because it prevented post surgical mortality and allowed fish monitoring throughout the entire life span of the transmitter. Our research can serve as a guide for future studies involving surgical implants of radio transmitters on native fish with high conservation values, in which mortality due to research should be minimal.