Protruding whip antenna radio transmitters were implanted in fish with abdominal pelvic fins. This surgical technique enables the transmitter to be positioned anywhere in the peritoneal cavity without piercing vital organs through the use of a shielded needle to guide an antenna along the intestine under the pelvic girdle. Results of this technique used on several species including some with thoractic ventral fins show that fish lived a minimum of 28 days after implantation, indicating that major damage to the internal organs had not occurred. Best results were obtained when fish were captured, tagged, and returned to open water.