Long-term effects of passive integrated transponder tags in far eastern catfish, Silurus asotus

Abstract

The aims of this study were to determine the most suitable site and the histological responses to passive integrated transponder (PIT) tags inserted into three sites in far eastern catfish, Silurus asotus. During the experimental period, the tag retention rate and readability rate were greater for dorsal tags than for abdominal cavity or tail tags (P<0.05). The standard length, body weight, growth rate (GRW), condition factor (CF), and specific growth rate (SGR) were not significantly different among the experimental groups (all P>0.05). GRW and SGR were lower in the winter than in the other season (P<0.05). In fish with abdominal tags, the tag was located in abdominal fat (in 60% of fish), around the kidney (15%), outside the air bladder (15%), or inside the air bladder (10%). Fibroblasts and a fibrous capsule were found in the tag site, but not in the epidermis. Melanopores and mucous cells were only found in the epidermis, and the area of mucous cells was larger than that of other cells in the epidermis. Based on the high rates of tag retention, readability, and survival, our results suggest that the dorsal muscle is the most favorable tag site for selective breeding systems of far eastern catfish.