Plasma Electrolyte Disturbance in Matrinxä, Brycon cephalus Transported Under Influence of Benzocaine

Physiological responses of matrinxä Brycon cephalus to hauling operations with benzocaine in the water were assessed. Thirty fish (mean weight =1.0 kg) were transported for 4 hours in 200-L tanks containing different concentrations of benzocaine: 0,5,10, and 20 mg/L. Blood samples were collected at departure (baseline condition), immediately after transport (arrival), and 24 and 96 hours later (recovery period). Plasma cortisol and serum potassium levels rose in fish from all treatments during transport and returned to the baseline condition 24 hours later. Blood glucose was elevated in all treatments after transport. Glucose levels offish transported in 0 and 5 mg/L benzocaine returned to the baseline condition after one day, while fish from treatments of 10 and 20 mg/L had hyperglycemia during the entire recovery period. Serum sodium and plasma chloride decreased during transport. Recovery of sodium occurred 24 hours later, except for fish from treatment of 20 mg/L, and plasma chloride recovered at 96 hours. Plasma ammonia increased during transport, especially for fish from treatments of 10 and 20 mg/L, and fish from treatment of 20 mg/L returned to the pre-transport status only in 96 hours. During the experimental period, 50% of the fish died after transport in 20 mg/L benzocaine; no fish died in the other treatments. The results indicate that transportation of matrinxä in benzocaine offered no advantages and 20 mg/L was harmful. © 2001 Taylor & Francis Group, LLC.