The use of alizarin red S and alizarin complexone for immersion marking Japanese flounder Paralichthys olivaceus (T.)

Alizarin red S from 200 to 400 mg/l and alizarin complexone from 50 to 300 mg/l were used to mark Japanese flounder, Paralichthys olivaceus. Immersion for 24 h produced detectable marks in sagittae, ctenoid, cycloid scales, fin rays (dorsal, anal, pectoral, caudal and ventral fin rays) and parts of dissected asteriscus after 60 days in culture. All treatment concentrations had good marks on otoliths. Violet marks were visible under normal light after marking with 200–400 mg/l ARS and 300 mg/l AC. Scales and fin rays showed acceptable fluorescent marks at higher concentrations (400 mg/l ARS, 300 mg/l AC and 250–400 mg/l ARS, 300 mg/l AC, respectively). The best results were obtained after marking with ARS at 400 mg/l and AC at 300 mg/l. There was no significant difference on survival and growth of marked fish relative to controls throughout experiment (P > 0.05).