Hemato-immunological and biochemical parameters of silver catfish Rhamdia quelen immunized with live theronts of Ichthyophthirius multifiliis.

This study investigated the immunization by intraperitoneal injection (i.p.) (assay I) and immersion bath (assay II) with live theronts of Ichthyophthirius multifillis in Rhamdia quelen and its influence on the hemato-immunological and biochemical parameters. Fish were divided in control (non immunized no challenged); non immunized and challenged with 12,000 theronts/fish; non immunized and challenged with 22,000 theronts/fish; immunized and challenged with 12,000 theronts/fish; immunized and challenged with 22,000 theronts/fish. Six days after challenge, either in the assay I or in the assay II the prevalence of I. multifillis in the gills was higher in non immunized fish (33.33% and 27.77%, respectively). In the assay I showed higher numbers of thrombocytes, leukocytes, lymphocytes, neutrophils and monocytes 20 days after injection and lower numbers after challenge. The immunoglobulin values were higher in fish non immunized. Fish immunized by immersion bath (assay II) showed greater values of catalase (CAT) in the liver (1245.49 U/mgprt) when compared to i.p. (198.79 U/mgprt). The levels of CAT in the liver of fish from the assay II were greater (1738.47 U/mgprt) 14 days after immunization than that observed 21 days after (1114.26 U/mgprt). The vaccination by i.p method showed influence on the hematological parameters. On the other hand, the immersion bath vaccination showed greater influence on the catalase activity in the liver. The results showed that new parameters like total protein, immunoglobulin and antioxidant enzymes could be considered in evaluating the host response to infection.

Hematological and histopathological changes in silver catfish Rhamdia quelen (Siluriformes) exposed to clomazone herbicide in the Madre River, Santa Catarina State, Southern Brazil.

This study evaluated the influence of the clomazone herbicide (2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone) contamination on the hematological parameters and histological changes in gills and liver of silver catfish (Rhamdia quelen) from Madre River, Santa Catarina State, Southern Brazil. Fish were collected between March 2010 and January 2012 at two different sites of the Madre River, one site receiving residual water (contaminated site) from rice culture (n=49) and another that do not receive residual water (reference site) (n=48). The herbicide clomazone analysis detected 3.40±1.70 µg/L in the contaminated site and 1.1±0.33 µg/L in the reference site. Fish from contaminated site showed increased (P<0.05) number of monocytes suggesting the possible defense response as a result of chronic exposure to clomazone. On the other hand, no difference was found in the hematocrit percentage, red blood cell count, total thrombocyte number, white blood cell count, lymphocytes, and neutrophils number. Fish from both sites showed histopathological changes in gills and liver, possibly caused by chronic exposure to contamination. The influence of herbicide sub doses on fish health is also discussed.

New technique for collecting eggs from monogenean parasites.

A novel and easily constructed apparatus for collecting monogenean eggs released by the parasites into the water is described and illustrated. Use of this technique may lead to a better understanding of the parasite's biology, which, in turn, may lead to the improvement of parasite management strategies in fish farms where monogeneans are potentially harmful to their hosts. The technique is also useful for studies of eggs or free-living stages of other fish parasites.