Copper sensitivity of wild ornamental fish of the Amazon

The copper sensitivity of 10 wild ornamental fish from Rio Negro, an ion-poor river in the Amazon, was analyzed in the absence of dissolved organic carbon (DOC). No mortality was observed at concentrations up to 700 μg Cu l−1 for two species exposed to CuCl2·2H2O dissolved in standard EPA-USA water. Copper sensitivity of fish was also tested in INPA groundwater, which is similar to that of the Rio Negro, but lacking typical DOC of Rio Negro water. In these experiments, all four characid fish species were more sensitive to copper than the catfish and the cichlids. LC50 values ranged from 12.8 μg Cu l−1 for the characid Hemigrammus rhodostomus to 74.1 μg Cu l−1 for the callichtyid Dianema urostriatum. Copper sensitivity of Hyphessobrycon socolofi was 52-fold lower in EPA (1405.5 μg Cu l−1) than in INPA water (26.8 μg Cu l−1). The differences in values of LC50 may be related to species-specific physiological abilities to ion-regulate under the original conditions of the habitat of the analyzed species.