Effects of Dimethoate Insecticide on Serum Biochemistry of African Catfish (Clarias gariepinus) Juveniles

The present study was designed to investigate acute toxicity of dimethoate on juvenile Clarias gariepinus. Catfish with mean weight and length of 24.01 ± 11.60 g and 13.98 ± 5.66 cm respectively were exposed to sub-lethal levels of dimethoate in static bioassay system for 28 days and mortality data was statistically evaluated using Finney’s Probit analysis. The 96-hour LC50 value for C. gariepinus was estimated as 29.05 mg/l. The value for the LC50 was used in deducing the sub-lethal concentrations (0.01, 0.15and 0.29 mg/l). Biochemical changes in the serum such as glycogen, total protein, cholesterol, urea and creatinine were analyzed after the exposure period (28 days). The glycogenlevel decreased in all sublethal exposures. An increase in cholesterol at lower exposure concentration, followed by slight increase in urea and creatinine among treated groups was recorded. Behavioural changes which includes changes in skin colour, jerking, restlessness, erratic swimming, among others were observed. Based on the result of this study, it was concluded that C. gariepinus juveniles are very sensitive to low concentration of dimethoate. Dimethoate is highly toxic to juvenile catfishes and as such measures must be taken to avoid its run-off into our aquatic environment thus jeopardizing the recruitment of juvenile catfishes into the fishery.

Sublethal behavioral and biochemical toxicity of cypermethrin in juvenile Oreochromis niloticus in a static bioassay

Sublethal behavioral and biochemical toxicity of cypermethrin in Oreochromis niloticus (L.) juveniles was accessed under static conditions at concentrations of 0.5, 1.1, and 2.1 µg L−1 for up to eight weeks. The juveniles were highly sensitive to cypermethrin, with a 96-h LC50 of 12 µg L−1. Biphasic trends were noted for four avoidance behaviors: loss of equilibrium; erratic swimming; air gulping; opercular ventilation. Dose- and duration-dependent increases occurred in mucus secretion and color change. Mixed trends were noted for mean glutamate pyruvate transaminase, triglycerides, proteins, and cholesterol. These parameters decreased significantly depending on dose and duration in weeks two and six, but they increased in week eight. Mean glucose and glutamic oxaloacetic transaminase increased significantly depending on dose and duration up to week eight. No differences in glucose were noted in the control in week two. The findings of the present study confirmed that cypermethin adversely affected the health of fish even at a sublethal level.

Effect of Euphorbia royleana on Growing Stages of Freshwater Fish Channa punctatus

In this study toxicity of Euphorbia royleana latex and stem bark extract was evaluated in a static bioassay test for the fry and fingerlings of freshwater fish Channa punctatus. For fry the LC50 values for Euphorbia royleana latex were 12.66, 6.27, 4.04 and 3.05 mg/L whereas for stem bark extract the LC50 values were 113.77, 89.16, 71.99 and 56.59 mg/L for 24, 48, 72 and 96 h, respectively. It seems that toxicity of latex was more pronounced as compared to stem bark extract. The LC50 values for latex for fingerlings were 22.58, 18.14, 14.99 and 12.34 mg/L whereas for stem bark extract the LC50 values were 614.35, 585.06, 535.93 and 475.37 mg/L for 24, 48, 72 and 96 h, respectively. The activities of the latex and stem bark extract were time- and dose-dependant. The present study clearly indicates that Euphorbia royleana extracts should be applied with great precautions nearby the aquatic reservoirs as it is toxic to growing stages of the fish.

Studies on the Acute Toxicity of Aldrin on Heteropneustes fossilis (Bloch) and Channa orientalis (Bloch and Schneider)

This paper deals with the toxicity of Aldrin to two freshwater fishes, Heteropneustes fossilis (Bloch) and Channa orientalis (Bloch and Schneider) to determine the acute toxicity. The LC50 values were obtained by using a static bioassay method for a period of 24, 48, 72 and 96-hour intervals. The LC50 values of Aldrin to H. fossilis were found to be 45, 35, 30 and 25.5 ppm and to C. orientalis to be 55, 35, 30 and 27 ppm for 24, 48, 72 and 96 hours, respectively. A profuse mucus secretion was evident at higher concentrations as compared to lower ones. In different test solutions, the fishes got excited showing frequent swimming, with increased opercular movements and frequent visit to water surface for gulping atmospheric air. The colour of the fish faded on gradually. Later, the fish became sluggish, settled down at the bottom and died.

Acute and Sub Lethal Effect of Potassium Cyanide on the Behaviour and ATPase Enzyme Activity in the Freshwater Fish, Clarias gariepinus (Catfish)

The Present research studies the acute sub lethal toxicity of potassium cyanide (KCN) in the fresh water, Clarias gariepinus and the effects on its behaviour and the Na+ - K+ ATPase enzyme activity. Acute toxicity of potassium cyanide (free cyanide) to the freshwater fish was studied using static bioassay method over a period of 96 h. Different concentrations of the toxicant (KCN) were used and LC50 value was found to be 361μg/L. Behavioural changes when exposed to lethal concentration of KCN showed increased feed intake, cannibalism, irregular swimming activity, rapid jerk movement, aggressiveness, loss of balance, opercula movement, surface behaviour, loss of equilibrium, change in body colour and convulsion. The effect of potassium on the Na+ - K+ ATPase of various physiological tissues which includes the gill, liver, muscles and intestinal over duration 0f 12 h-35 days were also studied. Cyanide intoxication resulted in marked changes in ATPase, shown by significant decrease in the enzyme activities. The result shows that ATPase enzyme together could be employed as a sensitive and useful biomarkers for cyanide pollution while the behavioural changes could be an early signal of toxicity.

Evaluation of acute toxicity of zinc, lead and cadmium to zooplanktonic community in upper Berach river system, Rajasthan, India

Current study investigated through static bioassay, the acute toxicity of Zinc,Lead and Cadmium to fresh water zooplankters in the upper Berach riversystem which is a part of Gangetic river system. The river basin stretchesfrom Madar tank to Sarjana tank with a total length of 46 Km, including ninewater bodies i.e. Bada madar tank (73‹36f0ffE and 24‹38f0hN ), Chhotamadar tank, Fateh sagar lake, Udaisagar lake, Up]stream pond (Bichhdi]I),Down]stream pond(Bichhdi]II), Gadwa, Daroli and Sarjana tank (73‹ 57f10hEand 24‹14f30h N). Whole zooplanktonic communities were exposed to different heavy metal stresses. Exposed zooplanktonic community included nine planktonic forms i.e. Heliodiaptomus viduus, Mesocyclops hyalinus, Heterocypris, Daphnia lumholtzi, Moina, Brachionus, Monostyla, Filinia. Cadmium was found to be most toxic and Zinc was least toxic to zooplankton. Ostracods and Cyclops were resistant forms and rotifers were sensitive forms in relation to metallic exposure. Sensitivity pattern observed during laboratory experiments was found to be in accordance with biodiversity variation of zooplankton in different ponds of Berach river system.

Histopathological Effects of Gammalin 20 on African Catfish (Clarias gariepinus)

Clarias gariepinusfingerlings exposed to lethal and sublethal concentrations of Gammalin 20 were investigated in a renewal static bioassay with particular reference to behaviour, survival, and histopathological changes. Early symptoms of gammalin 20 lethal poisoning were, respiratory distress, increased physical activity, convulsions, erratic swimming, loss of equilibrium, and increased breathing activity. Behavioural response was dose dependent and decreased with decreased concentration. The 96-hour lethal concentration (LC50) value was 30 ppb. Histopathological changes of the gill, liver, and intestinal tissues of fish treated with sublethal concentration of gammalin 20 for twelve weeks showed gill distortion and fusion of adjacent secondary lamella as a result of hyperplasia and excessive mucus accumulation. The liver showed swelling of hepatocytes with mild necrosis, pyknosis, and vacuolation, while the intestine showed yellow bodies of the lamina propria at the tip of the mucosal fold.