Behavioural and brain biomarker responses in yellowfin bream (Acanthopagrus australis) after inorganic mercury ingestion

To assess the effects of inorganic mercury ingestion on fish general behaviour and brain biochemical markers (acetylcholinesterase – AChE; lipid peroxidation – LPO; glutathione S-transferase – GST; catalase – CAT), juvenile yellowfin bream(Acanthopagrus australis) were fed mercury dosed food (low = 0.7 mg kg⁻¹, medium = 2.4 mg kg⁻¹ and high = 6 mg kg⁻¹) or undosed food (control = 0.2 mg kg⁻¹) for up to 16 days (5 replicates per treatment). Behavioural indicators, LPO levels and GST activity significantly changed overtime, but were not affected by mercury concentration. In contrast, CAT activity was higher in exposed fish in comparison to controls after 4 days, but not after 8 and 16 days. An additional depuration treatment was evaluated and fish from this treatment were less active and had significantly lower LPO levels and CAT activity than fish constantly exposed to the medium treatment. Overall, results from the present study indicate that a diet containing inorganic mercury impaired yellowfin bream growth and initially affected fish brain CAT activity, however fish were able to recover even with continuous exposure.