ABSTRACT:Malachite green has been used as an effective compound to control external fungal and protozoan infections of fish since 1933 but it has never been registered as a veterinary drug for use in food fish because of its potential carcinogenicity, mutagenicity and teratogenicity in mammals. The present paper reviews negative sideeffects of malachite green including its accumulation and persistence in fish that have been treated and describes other alternative substances for the treatment of fish and fish eggs.

The aim of the study was to evaluate acute toxic effects of the preparation Sencor 70 WG (metribuzin 70% W/V) on hematological, biochemical indices and histology of the common carp (Cyprinus carpio L.). In carp exposed for 96 h to Sencor 70 WG in the concentration of 250.2 mg/L, showed significantly lower (p<0.01) values of plasma total proteins, albumins, total globulins, triacylglycerols, lactate dehydrogenase, lactate, inorganic phosphate, hematocrit, hemoglobin concentration, mean erythrocyte volume, the leucocrite value, lymphocyte, and significantly higher (p<0.01) values of glucose, ammonia, calcium, monocytes, neutrophile granulocytes, developmental forms myeloid sequence and basophiles compared to the control group. Histopathological examination revealed hyaline degeneration of the epithelial cells of renal tubules of the caudal kidney. This alteration of kidney resulted in hypoproteinemia, followed by generation of transudate in body cavity.

AbstrAct:The aim of this study was to assess the effect of metribuzin on rainbow trout (Oncorhynchus mykiss). An experimental group of fish was exposed to Sencor 70 WG pesticide product (active substance 70% of metribuzin). The acute semistatical toxicity test lasting 96 h was performed on rainbow trout juveniles. The 96hLC50 value of Sencor 70 WG was 89.3 mg/l. An examination of the haematological and biochemical profile and histopathological tissue examinations were performed on one-to two-year-old rainbow trout after 96 h of exposure to Sencor WG 70 in a concentration of 89.3 mg/l. The experimental group showed significantly lower values (P < 0.01) of plasma total proteins, triacylglycerols, aspartate aminotransferase, ammonia, calcium, lactate, alkaline phosphatase, erythrocyte count, haematocrit and significantly higher (P < 0.01) values of erythrocyte haemoglobin compared to the control group. A significant decrease (P < 0.01) in both the relative and absolute lymphocyte count and a significant increase (P < 0.01) in both the relative and absolute count of neutrophile granulocytes were also recorded in the experimental group. The histopathological examination revealed mild proliferation of goblet cells of the respiratory epithelium of secondary gill lamellae and hyaline degeneration of epithelial cells of the renal tubules of the caudal kidney. This alteration of kidney resulted in hypoproteinaemia, followed by the formation of transudate in the body cavity. The metribuzin-based Sencor WG 70 pesticide product was classified among substances harmful to fish.

The aim of the study was to assess the effects of the anthelminthic, praziquantel, on the haematological and biochemical indices of the blood of common carp (Cyprinus carpio L.). Fish were divided into six groups: two groups received 30 mg kg(-1) body weight (bw) of praziquantel, and two groups were given 50 mg kg(-1) bw of praziquantel mixed into the heat-treated amyloid vehicle. Fish in the remaining two groups were given only the amyloid vehicle and were used as controls. Fish were examined either 24 or 96 h after administration. Praziquantel treatment was characterised by a significantly lower erythrocyte count, haemoglobin level, packed cell volume and total protein at both dose levels after 24 h compared with the controls, but these parameters were similar to the control values at 96 h. The activity of alanine aminotransferase (ALT) was significantly higher after 96 h in the treated groups, which could be attributed to slight hepatocyte damage caused by praziquantel. However, the differences between the treated and the control groups were not great, and we presumed that they were reversible.

The parasitic ciliate Ichthyophthirius multifiliis infests all species of freshwater fish and can cause severe economic losses in fish breeding. The most effective treatment, malachite green, has been banned in Europe and North America for use in food fish production. Peracetic acid (PAA) was found to be toxic to I. multifiliis theronts at low concentrations. I. multifiliis-infested carp were exposed to 1 mg/l PAA in a dynamic exposure by means of peristaltic pumps. Five days after infestation, gills, tail fins, and skin below the dorsal fin were observed microscopically for I. multifiliis abundance. After PAA exposure, PAA-treated fish showed lower infestation of I. multifiliis in all investigated tissues than the unexposed control fish. The infestation increased in the control group whereas the infestation in the PAA-exposed groups significantly decreased (p = 0.0083, Bonferroni correction). The fish in the two exposure groups showed a slight reinfestation with I. multifiliis. This might be caused by a peroxide degradation (hydrolysis) and/or reduction of the delivered PAA concentration. Thus, PAA concentrations were possibly too low to be effective on the released trophonts and/or the infective theronts. This hypothesis is corroborated by the fact that the I. multifiliis in the gills, skin, and fins of the PAA-exposed carp were in an early developmental stage.

No abstract

Performance and physiological traits and health of spontaneous and induced triploid tench are reviewed. Triploidy is best induced with cold shock; with triploids exhibiting 13.5-51.5% better weight gain, 2.69-3.94% higher slaughtering value, 20-60% lower gonadosomatic index, 0.9-4.5% higher dry matter in flesh and up to 107% more flesh fat than diploids, if farmed untill post sexual maturity. Triploids exhibit more abdominal fat and less polyunsaturated fatty acids of the n-3 and n-6 groups in the flesh. Triploid females are sterile, while triploid males may produce aneuploid spermatozoa with varying DNA content (1-1.9n) which may initiate development of embryos. Triploids have milder seasonal dynamics in their erythrocyte profile than the diploids. Thinner diffusion distance in gills of triploids than in diploids is interpreted as adaptation to lower aerobic capacity. Triploids show neither stronger tendencies to anatomic malformations, nor have bigger affinity to parasitic diseases than the diploids. Production of triploid tench could be an economically interesting method of farming to higher marketable weight, bringing a relatively high product quality.

The aim of the present study was to assess the effects of medicated feed, Rupin Special gran. ad us. vet. with oxytetracyclini chloridum as active ingredient (5 g·kg -1 feed), on physical and chemical characteristics of a pond ecosystem and the health of carp of two age groups in a pilot operation. The medicated feed was administered in 8 doses (15 g·kg -1 live weight). In the study, temperature, oxygen concentration, pH, microbiological, hydrobiological and hydrochemical variables of pond water were monitored. The fish health assessment was based on clinical, pathological-morphological and haematological examinations of 80 individuals in total. The examinations were made before, during, immediately after and 15 days after the administration of medicated feed. No effects on water quality were found. An important histological change after the application of 8 doses was the loss of haematopoietic tissue from the spleen, and dystrophic changes in the renal duct epithelium. A decrease in leukocyte and lymphocyte counts and in total blood plasma protein concentrations (P < 0.05) were observed already after the 3 rd dose of Rupin Special. It follows from the results of the study that Rupin Special should be used in only 4 (exceptionally 6) doses, compared to the originally recommended 8 doses. Fish treatment, haematology, histology, medicated feedFor the suppression and treatment of bacterial diseases in fish, an effective medication is required to which pathogenic microorganisms are sensitive. At present there are only two antibiotic preparations registered in the Czech Republic for application to fish. These are Flumiquil 50% plv. ad us. vet., a synthetic chinolon-based antibiotic with flumequin as an active ingredient, and Rupin Special gran. ad us vet., a tetracycline antibiotic with oxytetracycline (5 g·kg -1 ) as an active ingredient ( Koláfiová and Nepejchalová 2005).Rupin Special is a broad-spectrum antibiotic with activity against the majority of grampositive and gram-negative bacteria. Vitamin A (retinoli acetas) is present in the preparation mainly to improve the condition and resistance of the fish. Saccharin (saccharinum) and anise oil (anisi etheroleum) are added as taste correcting agents to guarantee that the feed is readily accepted by fish. Stabilizers and coating materials prevent undesirable changes in the preparation during its distribution or storage. Wheat flour is used as the vehicle of the preparation and this also increases the feed's nutritional value.Rupin Special is supplied in cylindrically shaped pellets about 3 -4 × 3-10 mm in size. The pellets are hard, and they soften when soaked in water, although they will retain their