Transport stress in matrinxã, Brycon cephalus (Teleostei: Characidae), at different densities

Matrinxã, Brycon cephalus, is a nativeteleost fish from the Amazon Basin, and is of economic importance forcultivation for food and sport in Brazil. Mortality losses due to handling andtransport of this stenohaline freshwater species are common. The effects oftransportation at different densities on the biochemical stress responses ofmatrinxã (mean weight 1 kg) were examined. Fish weresubjected to three different transport densities (100, 200, and 300 kgm^–3) for four h in water with added salt (0.6%). Thefish were bled at departure (baseline level), arrival (immediately aftertransportation) and at 24 and 96 h after arrival (recoveryperiod).Blood glucose, cortisol, sodium, chloride, potassium and ammonia were used asstress bioindicators. No mortality was observed and no alterations in plasmacortisol were registered. However, blood glucose and ammonia levels increasedand serum sodium and plasma chloride decreased on arrival for the fishtransported at the highest densities. These stress responses were transient andthe concentrations returned to baseline levels within 24 h. Thisstudy showed that matrinxã can be transported at densities as high asthose tested in the present study, at least under the conditions employed inthis study. A recovery period of at least 24 h is stronglyrecommended.