Stewart, D.R. and J.M. Long. 2011. Mass-marking Channel Catfish Fingerlings by Immersion in Oxytetracycline. Proceedings of the Oklahoma Academy of Science 91, 31-36.
Abstract
Oxytetracycline (OTC) has been extensively used for marking a variety of fish species,
but has never been successfully used to mark channel catfish Ictalurus punctatus. Channel
catfish fingerlings (~ 25 mm TL) obtained from the Oklahoma Department of Wildlife
Conservation at Byron Fish Hatchery were kept in Living Streams (791 to 1,018 L) equipped
with recirculation units. Marking trials consisted of immersing channel catfish in one
of three concentrations (250, 450, and 700 mg/L) OTC hydrochloride [HCl] for 6 hours.
Samples of channel catfish were obtained from each group at 1-week and 4-week postimmersion.
Lapilli otoliths and pectoral spines were removed to assess mark presence
with an epi-fluorescent compound microscope. After one week, no marks were detected
on pectoral spines for all treatments, mark detection on otoliths depended on concentration,
but never exceeded 43% (700 mg/L). After four weeks, all otoliths and pectoral
spines were determined marked for 700 mg/L OTC, 20% for fish immersed in 450 mg/L
OTC, and 0% were marked after four weeks at the 250 mg/L OTC. Results show, channel
catfish fingerlings can be successfully marked with immersion in OTC at 700 mg/L for at
least 6 hours. © 2011 Oklahoma Academy of Science.