THE EFFECT OF LONG-TERM THERAPEUTIC BATH OF MALACHITE-GREEN ON COMMONCARP (CYPRINUS-CARPIO L)

The aim of this paper was to determine acute toxicity of malachite gre en of the Vert Malachite J3E SA Crystaux type for common carp and to e valuate the effect of a 6-day therapeutic bath in 0.5 mg.l(-1) concent ration of this pharmaceutical on values of selected haematological ind icators including micronuclei test, as well as on histological composi tion of tissues of one-to two-year-old carp. The 48hLC50 value of the malachite green tested was 0.84 mg.l(-1). After the 6-day bath, change s in red blood picture [decrease in haematocrit value -PCV (P<0.001), decrease in mean corpuscular volume -MCV (P<0.05) and increase in mean corpuscular haemoglobin concentration -MCHC (P<0.01)] as well as in w hite blood picture/decrease in both relative and absolute monocyte cou nt (P<0.05 and P<0.01), respectively/were recorded in treated fish (n= 30) compared to the control group (n=29). Other indices of red and whi te blood picture in these fish did not differ from the control group. A decrease in total protein concentration (TP, P<0.01) in blood plasma was found in fish treated with malachite green. By means of a micronu clei test, no effect of long-term bath in malachite green on increase of their frequency in erythrocytes was proved. Histological examinatio n revealed mild regressive changes on gills, mild dystrophic changes i n parenchymatous tissues and an increased macrophage activity in treat ed fish. These changes indicate an increased sensitivity of the fish t reated with malachite green to hypoxia and impaired proteosynthesis.