Parasite fauna monitoring of matrinxã Brycon amazonicus (Spix & Agassiz, 1829) raised in an intensive husbandry system in a stream channel in the state of Amazonas, Brazil

Abstract

The matrinxã, Brycon amazonicus, is one of the main species being used for aquaculture and fishery activities in the Amazonian region, yet little is known about the parasites that cause its diseases. The present study monitored parasite fauna infesting an intensive husbandry system in a stream channel. The collections were carried out monthly from September, 1997 to January, 1998. Water quality parameters, fish removal procedures, as well as biometry and anaesthetic data were observed in order to monitor the management conditions. Of the 80 sampled fish, 71 (89%) were infested with four Monogenoidea species (Anacanthorus spiralocirrus, Jainus amazonensis, Tereancistrum kerri and Trinibaculum brazilensis), 12 (15%) one of Nematoda Spirocamallanus inopinatus, and three (3.75%) with the Copepoda Ergasilus bryconis. Monogenoidea presented the highest prevalence and intensity of infestation. The Kruskall-Wallis non-parametric variance analysis showed a significant difference (P < 0.05) in the monthly parasite indexes of A. spiralocirrus, J. amazonensis and T. brazilensis, however no significant difference (P > or = 0.05) was detected for T. kerri. Evaluation of the management conditions pointed out that monthly capture anaesthesia and hauling procedures may have been responsible for some of the clinical signals such as loss of scales, erosion and no pigments on the caudal fin and cornea opacity, which were the most frequently found injuries in husbandry.