Retention of Surgically Implanted Ultrasonic Transmitters in the Brown Bullhead Catfish

Our objective was to compare the ability of brown bullheads Ameiurus nebulosus to tolerate the implantation of ultrasonic transmitters with different coatings. A total of 14 brown bullheads were surgically implanted with ultrasonic transmitters; 7 transmitters were coated with paraffin wax and 7 with Scotchcast, an inert epoxy resin. Six brown bullheads were held as controls with no surgical procedures. Fish were held for 75 d in a flow-through, gravity-filtered series of tanks and monitored for transmitter expulsion, growth (i.e., percent relative weight change), condition (i.e., relative weight), and mortality. All fish with paraffin-coated implants retained their transmitters for the duration of the experiment, whereas two fish with Scotchcast implants expelled their transmitters within 50 d. All fish in the experiment survived, and the implanted fish exhibited growth and condition similar to those of the controls. On the basis of these results, we conclude that brown bullheads tolerate implantation of paraffin-coated transmitters and this attachment method may be used for brown bullheads in telemetric field studies.