Early biochemical biomarkers for zinc in silver catfish (<Emphasis Type="Italic">Rhamdia quelen</Emphasis>) after acute exposure

Contamination of aquatic ecosystems by metals causes various biochemical changes in aquatic organisms, and fish are recognized as indicators of environmental quality. Silver catfish were exposed to six concentrations of zinc (Zn): 1.0, 2.5, 5.0, 7.5, 10.0 and 12.5 mg/L for 96 h to determine the mean lethal concentration (LC₅₀). The value obtained was 8.07 mg/L. In a second experiment, fish were exposed to concentrations of 1.0 or 5.0 mg/L Zn and a control for 96 h. Afterward, the tissues were collected for biochemical analysis. Lipid peroxidation, as indicated by thiobarbituric acid-reactive substance (TBARS), decreased in the liver and brain for all Zn concentrations tested, while in the gills TBARS levels increased at 1.0 mg/L and declined at 5.0 mg/L. Zn increased protein carbonyls in the muscle of silver catfish and decreased it in the other tissues. The enzyme superoxide dismutase increased in both exposed groups. However, catalase did not change. Glutathione S-transferase decreased in the liver and increased in the gills (1.0 mg/L), muscle (5.0 mg/L) and brain (1.0 and 5.0 mg/L). Nonprotein thiols changed only in brain and muscle tissue. Zn exposure inhibited acetylcholinesterase (AChE) activity in the brain at both concentrations tested, but did not change it in muscle. Exposure to Zn inhibited the activity of Na⁺/K⁺-ATPase in the gills and intestine at both concentrations tested. Our results demonstrate that Zn alters biochemical parameters in silver catfish and that some parameters such as AChE and Na⁺/K⁺-ATPase could be considered as early biomarkers of waterborne Zn toxicity.     

Acute and chronic effects of aqueous ammonia on marbled spinefoot rabbitfish,Siganus rivulatus (Forsskål 1775)

Ammonia is a metabolite of aquatic organisms which might reach deleterious levels in intensive fish farms. The aim of the present study was to determine median lethal concentrations (96‐h LC₅₀) of total ammonia nitrogen (TA‐N) on marbled spinefoot rabbitfish (Siganus rivulatus) and chronic effects of TA‐N on survival, growth and behaviour of juvenile rabbitfish over a 50 day period. In the first experiment, fish were exposed to 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg L^?1 TA‐N for 96 h and survival evaluated. In the second experiment, 12 fish were stocked per 50‐L tank and treated with one of 0, 2, 4, 6, 8, 10 and 12 mg L^?1 TA‐N with three replicate tanks per treatment. Survival and growth were determined and histopathological alterations of gills due to chronic ammonia exposure were studied by light and electron microscopy. The 96‐h LC₅₀ values were 16–18 mg L^?1 TA‐N. In the chronic exposure experiment, fish reared in water with 0 mg L^?1 TA‐N had 100% survival and had 50% weight increase in 50 days. Fish at 2 and 4 mg L^?1 TA‐N all died whilst fish in 6, 8, 10 and 12 mg L^?1 TA‐N survived and grew albeit less than in treatment 0 mg L^?1. Gills from ammonia treated fish displayed severe histological and ultrastructural alterations including hyperplasia, hypertrophy and fusion of secondary lamellae, aneurysms and presence of pleomorphic altered cells. Chronic exposure to ammonia is deleterious to marbled spinefoot rabbitfish and low concentrations of ammonia appear to kill the fish in <50 days whilst fish can survive for more than 50 days at concentrations between 6 and 12 mg L^?1 TA‐N.     

Ammonia and nitrite toxicity to false clownfish <Emphasis Type="Italic">Amphiprion ocellaris</Emphasis>

False clownfish, Amphiprion ocellaris, is one of the most commercialized fish species in the world, highly produced to supply the aquarium market. The high stocking densities used to maximize fish production can increase ammonia and nitrite to toxic levels. In this study, A. ocellaris juveniles (1.20 ± 0.34 g) were exposed to six concentrations of ammonia ranged from 0.23 to 1.63 mg/L NH₃-N and eight concentrations of nitrite (26.3–202.2 mg/L NO₂ ^?-N). The LC₅₀- 24, LC₅₀-48, LC₅₀-72 and LC₅₀-96 h were estimated to be 1.06, 0.83, 0.75 and 0.75 mg/L for NH₃-N and 188.3, 151.01, 124.1 and 108.8 mg/L for NO₂ ^?-N. Analysis of gill lesions caused by sublethal concentrations of these nitrogenous compounds showed that both nitrogenous compounds induced tissue lesions such as hyperplasia of epithelium cells, hypertrophy of chloride cells and lamellar lifting to all concentrations tested. However, histopathological alterations were more conspicuous accordingly the increase of ammonia or nitrite in fish exposed to 0.57 mg/L NH₃-N or 100 mg/L NO₂ ^?-N. Based on our results, we recommend to avoid concentrations higher than 0.57 mg/L of NH₃-N and 25 mg/L of NO₂-N in water.     

The histopathology of carp, Cyprinus carpio L., exposed to microcystins by gavage, immersion and intraperitoneal administration

Carp liver, gills, intestine, kidneys, heart and spleen were studied by histology after the fish were exposed to microcystins by gavage, immersion and intraperitoneal administration. Intraperitoneal inoculation with microcystins caused necrosis or dose- dependent degeneration in the liver, gills and kidneys. Gavaging with microcystins caused changes in the histopathology of the liver and gills. Cellular degeneration and necrosis occurred in the liver, gills and kidneys when carp were introduced to a tank containing 1.7 μg ml^?1 of microcystins. Lesions were not observed in the heart, spleen or intestines from any of the treated carp. Microcystins administered by intraperitoneal injection at a concentration of 50 μg kg^?1 were lethal to all fish within 8 h, while gavaging with 250 μg kg^?1 of microcystins caused minimal damage in the tissues studied.     

Hematological and gill histopathological changes in iridescent shark,Pangasius hypophthalmus (Sauvage, 1878) exposed to sublethal diazinon and deltamethrin concentrations

The effect of two insecticides, diazinon and deltamethrin, was investigated on hematological parameters and gill morphology in iridescent shark, Pangasius hypophthalmus. Fish were exposed to 0.5 and 1 ppm diazinon as well as 0.015 and 0.020 ppm deltamethrin over a 7-day period. Both insecticides caused leukocytosis, lymphopenia, neutrophilia as well as increases in red blood cell (RBC), hematocrit (Ht), hemoglobin (Hb) and mean corpuscular volume (MCV). Morphological gill damages were observed in fish exposed to both pesticides. It is suggested that diazinon and deltamethrin changed immune function and induced gill damages which could be the reason of increase in RBC, Ht, Hb and MCV in iridescent shark.     

Dietary ascorbic acid reduced micronucleus and nuclear abnormalities in <Emphasis Type="Italic">Clarias gariepinus</Emphasis> (Burchell 1822) exposed to hospital effluent

Hospital effluents contain myriad of mutagens and genotoxins capable of increasing DNA damage in aquatic biota. African mudfish, Clarias gariepinus, are exposed to genotoxins when cultured in swamps and derelict water bodies often contaminated by effluents. Moreover, its DNA is susceptible to xenobiotic-induced lesions since it lacks l-gulonolactone oxidase and hence cannot synthesize l-ascorbic acid. This study investigated 96-h acute toxicity and protective effects of dietary ascorbic acid (AA) against micronucleus (MN) and abnormal nuclear (NAs) formation in C. gariepinus exposed to sub-lethal concentrations of hospital effluent. Six concentrations (0.5–3.0%) of the effluent were selected to determine the 96-h acute toxicity of the effluent in C. gariepinus, after range finding test. Fish were exposed to sub-lethal concentrations (0.08–1.30%) of the 96 h LC₅₀. Two other groups were exposed to the 96 h LC₅₀ (1.30%) of the effluent +50 and +100 mg/kg of dietary ascorbic for 7 days, and MN and NAs assessed in peripheral erythrocytes. The 96 h LC₅₀ (1.30%) was 1.18 times more toxic than the 24 h LC₅₀ (1.54%), indicating that the toxicity of the effluent increased with exposure duration. MN, nuclear bud, enucleated, fragmented nucleus (apoptosis), and necrotic erythrocytes significantly increase in effluent treated fish. Dietary AA reduced MN from 6.35-fold (1.30% treated group) to 3.72-fold (1.30% + 50 mg AA) and 3.54-fold (1.30% + 100 mg AA). Also, AA reduced total NAs from 2.26-fold (1.30%) to 1.40-fold (1.30% + 50 mg AA) and 1.06-fold (1.30% + 100 mg AA) compared to the control. Heavy metals and physicochemical parameters analyzed in the tested effluent possibly induced the mortality and cytogenotoxicity in C. gariepinus, and this was ameliorated by dietary AA.     

Lead accumulation and its effects on the branchial physiology of Prochilodus lineatus

The purpose of this work was to determine the tissue accumulation of lead (Pb) and its effects on osmoregulatory processes of the freshwater fish Prochilodus lineatus. Juvenile fish were exposed to Pb (from 1.7 to 0.7 mg of dissolved Pb L^?1) for 6, 24 and 96 h and Pb accumulation was analyzed in the gills, liver, kidneys, blood cells and muscle. The following parameters were also analyzed: hematologic (hemoglobin content, hematocrit and number of red blood cells), metabolic (blood glucose), endocrine (blood cortisol), osmo ionic (plasma osmolality and Na⁺, K⁺, Cl^? and Ca⁺² concentrations), gill enzymes (Na⁺/K⁺-ATPase and carbonic anhydrase), chloride cell (CC) density and CC location in the gills. Pb accumulated in all the analyzed tissues, with the kidneys showing the highest concentration, followed by the gills and liver. The lowest Pb concentrations were found in blood cells and muscle. Pb promoted an increase in blood glucose after 6 and 24 h exposure. Gill Na⁺/K⁺-ATPase was inhibited after 24 h of exposure, but its activity was restored at 96 h, probably due to the increase in CC in gill lamellae. Plasma Na⁺ was reduced after 6 and 96 h, while K⁺ concentrations increased at all the experimental times. Fish exposed to Pb showed reduced plasma Ca⁺² at all experimental periods. Hematologic parameters remained unchanged. Overall, this study demonstrated that Pb interferes in osmoregulatory processes of P. lineatus and the proliferation of CC in the gills is a response in order to reestablish adequate ion concentrations.     

Guanylyl cyclase stimulation by homologous and heterologous natriuretic peptides in salmonids

A range of homologous (trout ANP, trout CNP, trout VNP) and heterologous (eel ANP, eel ANP-NH₂, rat ANP, porcine CNP) NPs were tested for their effect on guanylyl cyclase in gill and kidney membrane preparations from freshwater and seawater-acclimated rainbow trout and Atlantic salmon. All NPs stimulated guanylyl cyclase at 1 μmol l⁻¹in all preparations. ANP was the most potent stimulator of kidney guanylyl cyclase and CNP the most potent stimulator of guanylyl cyclase in gills. Some differences were apparent between the potencies of homologous and heterologous peptides at 1 μmol l⁻¹: tANP was more potent than rANP in the SW trout kidney and tCNP was more potent than pCNP in FW salmon tissues. While eANP was more potent than tANP in trout gills, it was less potent than tANP in FW salmon gills. However, there was no significant difference between the potencies of eANP and eANP-NH₂ in trout or salmon gills. Salinity did not affect guanylyl cyclase activity with the exception that trout ANP at 1 μmol l⁻¹was more potent in SW trout kidneys than in FW trout kidneys. These results suggest a predomination of NPR-A in the kidney and NPR-B in the gill. It appears that salmonid NPR-A and NPR-B are relatively promiscuous in their ligand affinity, with few differences in the potencies of trout and mammalian NPs and only small differences in cGMP production where these differences do occur. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hematological, biochemical, and behavioral responses of Oncorhynchus mykiss to dimethoate

The effects of dimethoate on hematological, biochemical parameters, and behavior were investigated in Oncorhynchus mykiss exposed to sublethal concentrations of 0.0735, 0.3675, and 0.7350 mg/l for 5, 15, and 30 days. Significant decrease was determined in erythrocyte and leukocyte counts, hemoglobin, hematocrit, MCV, and MCH, which was pronounced after prolonged exposure indicating the appearance of microcytic hypochromic anemia. There were no prominent changes in thrombocyte and MCHC. The glucose concentration showed an ascending pattern that proved to be positively correlated with duration. The protein concentration declined in higher dimethoate concentrations following 15 and 30 days. Negative and significant correlation was detected between glucose and protein concentrations. The fish showed remarkable behavioral abnormality such as loss of balance, erratic swimming, and convulsion. Present findings revealed that dimethoate exerts its toxic action even in sublethal concentrations and hematological parameters and abnormal behavior may be sensitive indicators to evaluate pesticide intoxication.     

Toxicological and hematological effect of <Emphasis Type="Italic">Terminalia arjuna</Emphasis> bark extract on a freshwater catfish, <Emphasis Type="Italic">Heteropneustes fossilis</Emphasis>

Increasing demand for eco-friendly botanical piscicides and pesticides as replacements for harmful synthetic chemicals has led to investigation of new sources of plant materials. Stem bark of Terminalia arjuna, which has been used as a popular folk medicine since ancient time, was examined for its piscicidal activity. This study aims to determine toxicity of ethanol extract of T. arjuna bark on fresh water stinging catfish (Heteropneustes fossilis), along with evaluation of changes in hematological parameters of the fishes exposed to a lethal concentration. The percent mortality of fishes varied significantly in response to concentrations of the extract and exposure times (between exposure time F = 36.57, p < 0.001; between concentrations F = 39.93, p < 0.001). The lethal concentrations (LC₅₀) of ethanol extract were found to be 12.7, 8.94, 5.63 and 4.71 mg/l for 24, 48, 72 and 96 h, respectively. During acute toxicity test, blood samples of treatment fishes showed significant decreases in the red blood cells count, hematocrit content, hemoglobin concentration, mean corpuscular hemoglobin concentration and plasma protein level when compared to those of the control group, while there were significant increases in the mean corpuscular volume, mean corpuscular hemoglobin, white blood cells count and plasma glucose concentration. These results suggest that T. arjuna bark extract could be considered as a potent piscicide due to its toxic effect on fish, particularly fish hematology.     

Effect of vitamin C dietary supplementation in reducing the alterations induced by fenitrothion in Oreochromis niloticus

The objective of this study was to investigate the dietary effect of vitamin C in amelioration some of studied alterations induced by fenitrothion in Nile tilapia (Oreochromis niloticus). Nile tilapia was exposed to sub-lethal concentration of fenitrothion 0.04 mg/l (96 h LC₅₀ value was 0.8 mg/l), and basal diet was supplemented with two different dose of vitamin C (500 and 1200 mg/kg B wt/day) for 30 days. Vitamin C supplemented groups showed significant decrease in plasma cortisol and glucose level, enzymes activity of liver and gills (catalase, glutathione-S-transferase and superoxide dismutase) and % of tail DNA damage compared to exposed group. Moreover, fish revealed significant increase in total plasma protein, albumin, globulin and A/G ratio. High dose of vitamin C dietary supplementation (1200 mg/kg B wt/day) returns these parameters to its normal levels with no significant difference compared to non exposed control group. These results indicated that incorporation of high dose of vitamin C (1200 mg) in aqua feed for 30 days could be potentially less expensive and effective in reducing the alterations induced by fenitrothion in Nile tilapia.     

Effect of feed supplementation with kynurenic acid on the morphology of the liver,kidney and gills in rainbow trout (Oncorhynchus mykiss Walbaum, 1792), healthy and experimentally infected with Yersinia ruckeri

Kynurenic acid (KYNA) is an endogenous substance produced on the kynurenine pathway which is primarily known for its neuroactive properties. Recently, it has been proven that KYNA is a selective ligand for G protein‐coupled receptor (GPR 35), presented on immunocompetent cells such as T lymphocytes. This opens up new possibilities of its application as an immunostimulating substance in aquaculture. Thus far, no histopathological investigations in fish have been completed to evaluate influence of KYNA supplementation in feed. This study has been undertaken to determine the effect of feed supplementation with KYNA (2.5, 25, 250 mg kg^?1 of feed) for 28 days on the liver, gills and kidney in healthy fish and experimentally infected with Yersinia ruckeri. In a control group were observed a fatty liver, which is natural for this fish species in the autumn and winter season. As the dose of the supplement was increased, the fat liver changed, it decreased or completely disappeared. Additionally, inflammatory changes occurred in all the analysed organs, and their intensification was dose dependent. In the fish experimentally infected, KYNA caused aggravation of the signs in the liver, kidneys and gills, and the effect was dose dependent. The results implicate that KYNA may be a stressor for fish.     

Acute Toxicity and Sublethal Effects of Nitrite on Selected Hematological Parameters and Tissues in Dark-banded Rockfish, Sebastes inermis

Acute toxicity and sublethal effects of nitrite in dark‐banded rockfish, Sebastes inermis (83.3 ± 7.2 g), were studied under static conditions for a period of 96 h. The acute toxicity of nitrite evaluated for the 96‐h lethal concentration (LC₅₀) was 700 mg/L. The sublethal effects on selected hematological parameters of S. inermis, such as total erythrocyte count (TEC), hemoglobin, plasma glucose, and serum protein content, were measured after 0, 6, 12, 24, 48, 72, and 96 h of exposure to 0, 50, 100, 200, 400, and 700 mg/L of nitrite. Sublethal nitrite caused progressive reduction in the TEC, hemoglobin, and serum protein content in fish depending on the nitrite concentration and exposure period. The 96‐h exposure resulted in a 14–42% reduction in TEC and 25–33% reduction in hemoglobin content for 100–700 mg/L of nitrite compared to the control. A dose‐related reduction in plasma glucose (25.7–34.2%) was observed for concentrations of 200–700 mg/L of nitrite during 48 h of exposure, followed by an increase through 96 h. A significant reduction in serum protein (7.3–12.6%) was observed for 200–700 mg/L of nitrite after 96 h of exposure. Abnormal histological changes in skin, gill, liver, and kidney tissue were observed in fish exposed to 700 mg/L of nitrite after 96 h of exposure compared to the control. Although no mortality of S. inermis occurred at 500 mg/L of nitrite, all hematological parameters adversely responded to a nitrite dose of 200 mg/L for 96 h. These results showed that although acute toxicity concentration of nitrite in S. inermis is higher than 700 mg/L, sublethal concentrations of nitrite also negatively affect hematological parameters.     

Alteration in haematological and biochemical parameters of Catla catla exposed to sub-lethal concentration of cypermethrin

A 60-day experiment was carried out to study the effect of sub-lethal concentration of cypermethrin (1/10th of LC₅₀) exposure on haematological and biochemical parameters of the Indian major carp, Catla catla fingerlings. Under exposure, the total erythrocyte count, total leucocyte count, haemoglobin content and haematocrit were decreased. All the studied serum parameters viz. total serum protein, albumin, globulin contents and albumin–globulin ratio were significantly decreased in cypermethrin-exposed fishes. A marked increase was recorded in alanine aminotransferase and aspartate aminotransferase activities in liver, whereas lactate dehydrogenase activity of muscle and acetylcholine esterase activity in brain were inhibited in cypermethrin-exposed fish. The membrane transport enzymes (total adenosine triphosphatase, sodium–potassium adenosine triphosphatase and magnesium adenosine triphosphatase) activities were decreased significantly in the gills of C. catla exposed to sub-lethal concentration of cypermethrin. The present study indicates that sub-lethal exposure of C. catla fingerlings to cypermethrin alters the haematological and biochemical parameters.     

Effect of oxidation–reduction potential on performance of European sea bass (Dicentrarchus labrax) in recirculating aquaculture systems

The direct impact of oxidation–reduction potential (ORP) on fish welfare and water quality in marine recirculating aquaculture systems (RAS) is poorly documented. In this study, the effects of the fish size (S₁, S₂, S₃) and ORP level (normal, four successive levels) on the performance of European sea bass (Dicentrarchus labrax) were investigated. Three size fish were distributed into two RAS (RAS and RAS O₃). Ozone was injected into RAS O₃ to increase the ORP level. The ORP was stabilized to four successive levels: 260–300, 300–320, 320–350, and 300–320 mV in fish tanks during four periods (P_1–4). At the last day of each period, the hematological parameters, plasma protein and mortality of sea bass were analyzed. Two-way ANOVA revealed that several hematological parameters, including pH, hematocrit, concentrations of oxygen, carbon dioxide, glucose (Glu), ionized calcium, kalium, and hemoglobin, were significantly influenced by the increased ORP levels over the experimental period. The alteration in blood Glu and plasma protein concentration showed that ORP around 300–320 mV started to stress sea bass. Once the ORP exceeded 320 mV in the tanks during the P₃ period, mortality occurred even when total residual oxidants/ozone-produced oxidants was only 0.03–0.05 mg L^?1 in the fish tanks. At the same time, plasma protein decreased notably due to appetite depression. After the decrease in ORP during the P₄ period, mortality continued. In conclusion, the results strongly suggest that for European sea bass in RAS, the ORP should not exceed 320 mV in the tanks. Once ozonation damaged fish, the effect seemed to be irreversible. However, how ORP affected related hematological parameters still need the further investigations.     

Air-breathing behavior and physiological responses to hypoxia and air exposure in the air-breathing loricariid fish, Pterygoplichthys anisitsi

Hypoxic water and episodic air exposure are potentially life-threatening conditions that fish in tropical regions can face during the dry season. This study investigated the air-breathing behavior, oxygen consumption, and respiratory responses of the air-breathing (AB) armored catfish Pterygoplichthys anisitsi. The hematological parameters and oxygen-binding characteristics of whole blood and stripped hemoglobin and the intermediate metabolism of selected tissue in normoxia, different hypoxic conditions, and after air exposure were also examined. In normoxia, this species exhibited high activity at night and AB behavior (2–5 AB h^?1). The exposure to acute severe hypoxia elicited the AB behavior (4 AB h^?1) during the day. Under progressive hypoxia without access to the water surface, the fish were oxyregulators with a critical O₂ tension, calculated as the inspired water O₂ pressure, as 47 ± 2 mmHg. At water O₂ tensions lower than 40 mmHg, the fish exhibited continuous apnea behavior. The blood exhibited high capacity for transporting O₂, having a cathodic hemoglobin component with a high Hb–O₂ affinity. Under severe hypoxia, the fish used anaerobic metabolism to maintain metabolic rate. Air exposure revealed physiological and biochemical traits similar to those observed under normoxic conditions.     

Effect of starving and feeding on some haematological and physiological responses of the Nile catfish, <Emphasis Type="Italic">Clarias gariepinus</Emphasis> exposed to copper at extreme seasons

The lethal concentration for 50% of fish for 96h (96h LC₅₀) of copper (Cu²⁺) was estimated for the Nile catfish (Clarias gariepinus) in extreme seasons, winter and summer, 4.31 and 4.79 mg/l, respectively. The Nile catfish was exposed to 96h LC₅₀ of copper for 7 days in extreme winter and summer. The body indices, haematological parameters as well as some plasma and liver enzyme activities and metabolite level were significantly differed in fish exposed to copper over than those of the control fish. Most of the tested parameters were not significantly different between the control fish of winter and summer (winter, water temperature 18 ± 2°C and summer, 27 ± 2°C). The effect of two ration sizes on copper toxicity in two different seasons on C. gariepinus was justified. It was found that the haematological parameters and the tested plasma activities of enzymes were significantly valid due to season differences. The blood parameters as well as plasma activities of enzymes were significantly differed in fishes fed elevated ration (3%) and exposed to copper challenge. On the other hand, the exploit of low feeding ration (0.5%) along with copper exposure during the examined seasons induced non-significant differences of the tested parameters, from those of the corresponding control. Therefore, the low feeding ration provides some tolerance against the possible water-borne copper exposure.     

Toxicity of Four Chemotherapeutic Agents to Rabbitfish Siganus rivulatus

As aquaculture evolves from extensive pond culture to intensive tank and cage systems, chemical dips and baths are increasingly being used to treat a concomitant increase in ectoparasitic and bacterial infestations. Some of the main disease‐causing agents are ectoparasites on the skin and gills of fish. Consequently, application of chemotherapeutics is increasing in aquaculture industries in order to control outbreaks of parasitic infestations. However, the toxic effect of commonly used chemotherapeutic agents on specific aquacultured fish species is often unknown. The present work was performed to test the effect of four commonly used chemical treatments on rabbitfish, Siganus rivulatus. The lethal concentrations for 50% of population (LC₅₀) of formalin, copper sulfate, potassium permanganate, and hydrogen peroxide for S. rivulatus juveniles treated for 1 h were assessed. Formalin and potassium permanganate tolerance values were determined by calculating 72‐h LC₅₀ values through probit analysis. The 72‐h LC₅₀ values for the formalin toxicity tests were 551.0 and 1.68 mg/L, respectively. LC₅₀ of copper sulfate and hydrogen peroxide could not be determined from the concentrations tested but were found to be >3 and >700 mg/L, respectively. Accordingly, treatment concentrations of formalin and potassium permanganate used for other fish species could be lethal to S. rivulatus, but the species appears to be quite tolerant to copper sulfate and hydrogen peroxide.     

Effect of glyphosate-based herbicide on hematological and hemopoietic parameters in common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L)

The effects of Roundup (glyphosate-based herbicide) on peripheral blood parameters and hematopoietic tissue cellular composition and activity in common carp juveniles were evaluated. The fish were exposed for 7 days at 0.0, 0.1, 0.5, or 5.0 mg/L of glyphosate. In fish exposed to Roundup, hematological alterations were observed; however, most of them were not directly related to the herbicide concentration. An increase in Ht and MCV, and decrease in Hb, MCH, and MCHC compared to the control were observed. Fish exposed to Roundup showed also a reduction in WBC and oxidative metabolic activity of phagocytes (NBT) compared to the control. The fish exposed to 0.1 and 5.0 mg/L showed increased glucose values, whereas in those subjected to 0.5 mg/L blood glucose concentration declined compared to the control. Cholesterol significantly increased at 0.1 mg/L and decreased at 5.0 mg/L. Analysis of head kidney hematopoietic tissue revealed that Roundup at concentrations 0.5 and 5.0 mg/L caused a significant increase in the rate of cell proliferation accompanied by an increase in frequency of early blast cells. No significant differences occurred in percentages of most cell lineages but the frequency of monocytoid, eosinophilic, and basophilic lineage cells significantly increased in the herbicide-exposed fish compared to the control. The obtained results revealed that sublethal concentrations of Roundup that may occur in polluted natural waters caused a slight anemic and significant immunosuppressive response in common carp juveniles. On the other hand, they indicate a considerable compensatory potential of carp hematopoietic system.