Physiological and biochemical responses of silver catfish, Rhamdia quelen, after transport in water with essential oil of Aloysia triphylla (L'Herit) Britton

Abstract

This study investigated the efficacy of the essential oil of Aloysia triphylla in the transport of silver catfish (Rhamdia quelen) considering survival, water quality, ionoregulatory balance and biochemical parameters. Fish (262.0±73.5g) were divided into three groups: 0 (control), 30 or 40μL/L EO of A. triphylla was added to the water and transported in plastic bags for 6h. At the end of transport, dissolved oxygen, alkalinity, pH, temperature, and un-ionized ammonia levels in the water of transport were not significantly different between treatments, but the control group presented the highest total ammonia levels. Fish transported with the EO of A. triphylla had lower plasma cortisol and ion loss and higher plasma Na+ and Cl− levels than control group. Hepatic glycogen, lactate and glucose levels were lower in the liver of fish transported with EO of A. triphylla when compared to the control. Total free amino acids and protein values in the liver were higher in the treatment with 40μL/L EO of A. triphylla. Muscle lactate and glucose levels were higher and lower, respectively, in fish transported with EO of A. triphylla compared to control fish. Thiobarbituric acid-reactive substance levels in the liver and muscle were lower in silver catfish transported with EO of A. triphylla when compared to the control fish. Catalase (CAT) activity was lower in the kidney and higher in the gill of fish transported with EO of A. triphylla when compared to controls. On the other hand, hepatic CAT activity was lower and higher in fish transported with 30 and 40μL/L EO of A. triphylla, respectively, when compared to controls. Protein carbonyl contents of fish transported with EO of A. triphylla were lower when compared to the control. Based on the reduced plasma cortisol levels, ammonia excretion, ionoregulatory changes and improved fish oxidative status, the use of EO of A. triphylla in the water of transport is advisable for fish transportation, 40μL/L being the best concentration.