The effect of tramadol hydrochloride on early life stages of fish

• Effect of tramadol hydrochloride on fish early life stages was studied.
• Hatching,early ontogeny and both morphometric and condition characteristics were influenced.
• Changes in antioxidant enzyme activity were observed.
• Environmental concentrations of tramadol hydrochloride have effects on aquatic vertebrates.

The aim of this study was to perform the fish embryo acute toxicity test (FET) on zebrafish (Danio rerio) and the early-life stage toxicity test on common carp (Cyprinus carpio) with tramadol hydrochloride. The FET was performed using the method inspired by the OECD guideline 236. Newly fertilized zebrafish eggs were exposed to tramadol hydrochloride at concentrations of 10; 50; 100 and 200 μg/l for a period of 144 h. An embryo-larval toxicity test on C. carpio was performed according to OECD guideline 210 also with tramadol hydrochloride at concentrations 10; 50; 100 and 200 μg/l for a period of 32 days.Hatching was significantly influenced in both acute and subchronic toxicity assays. Subchronic exposure also influenced early ontogeny, both morphometric and condition characteristics and caused changes in antioxidant enzyme activity. The LOEC value was found to be 10 μg/l tramadol hydrochloride.