Effects of thymol: carvacrol association on health and zootechnical performance of tambaqui Colossoma macropomum

Research in aquaculture shows that thymol and carvacrol are promising additives in fish diets. In this study, the effects of the thymol:carvacrol combination on health parameters and the zootechnical per-formance of tambaqui (Colossoma macropomum) were evaluated. The compounds were incorporated into five concentrations of feed. At intervals of 30 and 60 days, fish were sampled to evaluate haemato-logical, biochemical, and immunological parameters, and after 60 days, zootechnical performance, pa-rasitic load, and resistance to bacteriosis were evaluated. After 30 days, fish that received the highest concentrations of thymol:carvacrol showed a reduction in the number of thrombocytes and lympho-cytes and an increase in eosinophils (p <= 0.05). After 60 days of feeding, haematological parameters were similar between all groups. Regarding the antiparasitic effect of the compounds, all groups had a high parasitic load (monogenean infestation). Regarding the prevention of bacteriosis, high mortality was detected in all groups after the experimental challenge with Aeromonas jandaei, with no greater protection for fish fed thymol:carvacrol. In conclusion, it was observed that haematological results corroborate with research on mammals, in which the anti-inflammatory/immunosuppressive effects of thymol and carvacrol are highlighted. However, the use of additives for aquaculture should be dis-cussed carefully, as the cost-benefit of supplementation is not a consensus.