Evaluation of subcutaneously implanted visual implant tags and coded wire tags for marking and benign recovery in a small scaleless fish, Galaxias truttaceus (Pisces: Galaxiidae)

Abstract

Visual implant (VI) tags and coded wire tags (CWTs) were tested as methods for marking a small galaxiid fish, Galarias truttaceus, in such a way as to allow benign information recovery. VI tags were implanted beneath the skin of the preoperculum and CWTs were implanted between caudal fin rays. Both types of tag were easily implanted into fish >90 mm total length (4-5 g). Retention rates of both tag types were evaluated under field conditions. Retention of VI tags implanted in the preoperculum was estimated at 100% after 14 days and 92% after 131 days. There was a loss of 8-18% of CWTs within the first four weeks after tagging. Tag loss continued more gradually thereafter and retention was estimated at 71% after 131 days. It was demonstrated that both types of tags could be applied successfully to four other species of Galaxias.