Passive integrated transponder (PIT) tags only work in very close proximity of the receiver (cm distance). Therefore, active transponders are mainly used in behavioural monitoring. In the present study, the effects of intraabdominal implantation of PIT tags on survival, well-being and growth performance of juvenile turbot (Scophthalmus maximus) were investigated. Furthermore, the tag retention rate and read out error rate of all tags were examined. Passive integrated transponder tags were implanted in the abdominal cavity of nearly 6 000 turbots. All tags were readout and checked for correct function over a period of 122 days every five and a half weeks. No significant effects of tagging on fish survival (mortality rate <0.2 %), health or growth were detected during the trial period. Tag retention rate was 100 % and no malfunctions were observed. Results suggest that turbots can be marked with PIT tags in the abdominal cavity without obvious negative influences on performance traits and tag retention rate.