Evaluation of PIT‐tagging in cyprinids

Laboratory and field experiments were used to investigate how different marking procedures, with 23 mm PIT (passive integrated transponders) – tags, affected mortality, body condition and tag expulsion in small roach Rutilus rutilus and rudd Scardinus erythrophthalmus (117 to 163 mm total length). In a laboratory experiment mortality was low (≤ 6%) and only occurred among fishes that had their incision closed with sutures. The latter also had a specific growth rate that tended to be lower than the fish tagged without sutures. The different marking procedures did not adversely affect the body condition of fishes either in the laboratory experiment (after 37 days) or in the field experiment (up to 369 days). No tag expulsions were observed among laboratory fishes PIT‐tagged without sutures. Marking without the use of sutures to close the incision, appears to be the most appropriate PIT tagging procedure for small cyprinids.