Nighttime Electrofishing on the Silver River

Oklawaha River Aquatic Preserve and FWC Freshwater Fisheries biologists partnered together to attempt a nighttime electrofishing event on the Silver River to remove invasive tilapia. FWC’s past attempts in spring systems during the daytime were not successful because the tilapia were spooked before the electrofishing boat could even get close enough to deliver an effective electrical pulse. We went in with low expectations, but shockingly, the nighttime electrofishing was much more successful! As the tilapia were sleeping in the shallow areas, we were able to get right on top of them to deliver a direct shock. Other fish typically float to the surface for about a minute after the shock, but tilapia’s thick, hard scales prevent them from being completely stunned. Instead, they perform a few evasive somersaults before darting away to warn their friends. Netting them has to be quick and tactical, which was the biggest challenge and skill development of the night. After three hours of shocking and swapping turns to give muscles a rest, the boat was filled with 68 tilapia! With these tilapia averaging around 7 pounds each, that’s over 400 pounds! This brings the total number of tilapia removed from the Silver River in 2025 to 263. Most of the species identified were blue and Nile tilapia hybrids, which was great information to learn as we build up this removal effort and share knowledge with partners. Regardless of the number of fish removed, we learned a lot about nighttime tilapia behavior that will hopefully be helpful for other removal attempts around the state. FWC is interested in trying this again in the winter with additional boats. Lastly, a special thanks to the staff of Silver Springs State Park for allowing us access after hours.