PRELIMINARY STUDY ON THE EFFECTS ON JUVENILE

PACHECO MARINO, S.G; PLAUL, S.; ANDRÉS LAUBE, P.F.; BARBEITO, C.; SALIBIÁN, A.

La Plata

Congreso; IX Congreso y 6tas Jornadas de educación de la Sociedad de Ciencias Morfológicas; 2007

AAPVET

The objective of the present work was to obtain some preliminary knowledge of the effects of the Malachite Green (MG) on juvenile pejerrey Odontesthes bonariensis (Valenciennes, 1835). In order to perform the toxicological trials, specimens, of 39 days of age were used. Semi static bioassays with daily renewal of the media were performed; the temperature was kept constant at 17 °C and the photoperiod was natural. Fours  concentrations were tested  [0.0 (controls), 0.1, 1.0 and 10.0 ppm]. The MG solutions were prepared with reconstituted US EPA hard water (pH: 7.6-8.0; hardness 160-180 mg CaCO3/L; alkalinity: 110-120 mg CaCO3/L). Five individuals were incubated in each solution. Survival was recorded every 24 hours, during two days. At the end of the assays fish were fixed in phosphate-buffered formaldehyde. A mortality of 100% was observed at the highest concentrations after 24 hours. 48 hr exposure no mortality was recorded in the group exposed to 0,1 ppm as well as in the control group. The histopathological analysis of the samples showed that the most affected organ by MG at 1.0 ppm was the liver; degenerative lesions were found in some of the individuals which appeared spread to the whole organ. We concluded that under our experimental conditions the toxic effect is dose-dependent; the highest concentration of MG resulted lethal for juvenile pejerrey.