Safest level of tricaine methanesulfonate (ms-222) to induce anesthesia in juveniles of Matrinxã, Brycon cephalus

The use of MS-222 as an anesthetic for matrinxã juveniles was investigated. At dosage of 100 mg/L or lower fish did not achieve a complete anesthesia state. At 150 mg/L, MS-222 induced anesthesia within 36 seconds and recovered from a 10 minutes period of anesthesia within 5.2 min. Higher concentrations (200, 250 and 300 mg/L) anesthetized fish in lesser times, with the offset of mortality (16.7 and 33.3%) at the 200 and 300 mg/L MS-222 doses, respectively. The only significant differences observed in the hematological parameters, was for the glucose values in fish anesthetized with 250 and 300 mg/L. From the results, the recommended dose of MS-222 for handling matrinxã juveniles is 150 mg/L.