Alive, healthy and disease free fishes (Channa gachua, weight 15-20gm and length 12-18cm) were used for the experiment. The fishes were procured from the local fish market, Bhopal and brought to the laboratory. The fishes were kept in the glass aquaria to observe any visible pathological symptoms. Before introducing into the aquarium, fishes were treated with 0.1%KmNO₄ solution to obviate any dermal infection.

Fishes were acclimatized to laboratory conditions for a period of one week. No mortality was recorded during this period. The fishes were fed with chopped meat daily. After acclimatization, fishes were kept in different concentrations of dichlorvos in different aquaria.

Dichlorovos DDVP (20%EC) was obtained from the local market. Renewal toxic test method (APHA, 1992) was used to find out the LC₅₀ concentration. Fishes were exposed to sub-lethal concentration for 16, 24 and 48 hours in acute studies and 15, 30 and 45 days in chronic studies. Control fish were also maintained under identical conditions without pesticide in the medium.

At the end of the exposure period, blood was collected from the dorsal arota into plastic vials containing 0.1ml of EDTA. Then, the blood was gently mixed with the oxalate mixture to avoid coagulation. Various biochemical tests were performed by using the kit procured from MERCK.

The obtained data was subjected “t” test find out the significance of difference between control and treated values.

In 16 hrs exposed fishes, the recorded values of plasma glucose, cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, total protein, serum bilirubin, serum creatinine, SGPT, SGOT and lipid peroxidation were 62.213mg/dl, 168.33 mg/dl, 138.367 mg/dl, 298.0 mg/dl, 4.17 mg/dl, 3.017 mg/dl, 1.058 mg/dl, 99.25 µl, 652.667 µl, and 0.552 mg/dl, respectively (Table 1).

In 24 hrs exposed fishes, the value of plasma glucose, cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, total protein, serum bilirubin, serum creatinine, SGPT, SGOT and lipid peroxidation were 56.265 mg/dl, 182.0 mg/dl, 146.0 mg/dl, 307.0 mg/dl, 3.99 mg/dl, 2.533 mg/dl,0.732 mg/dl,95.667 µl, 691.167µl, and 0.147mg/dl, respectively (Table 1).

In case of 48 hrs exposed fishes, the value of plasma glucose, cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, total protein, serum bilirubin, serum creatinine, SGPT, SGOT and lipid peroxidation were 44.406 mg/dl, 210.0 mg/dl, 168.0 mg/dl, 310.0 mg/dl, 4.112 mg/dl, 2.553 mg/dl, 1.00 mg/dl, 97.833 µl, 765.83 µl, and 0.458 mg/dl, respectively (Table 1).

Figure 1

Table - 1. Sub-lethal effect of Dichlorovos on certain biochemical parameters of (Ham.) - Acute Studies (0.012mg/l)

Values expressed in Mean ± S.D. of 6 replicates. Student “t” test was performed between control and treated values. The mean values are found to be significantly different at 1% level of significance (P<0.01). (* - not significant)

In 15days exposed fishes, the recorded values of plasma glucose, cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, total protein, serum bilirubin, serum creatinine, SGPT, SGOT and lipid peroxidation were 58.951 mg/dl, 165.55 mg/dl, 138.367 mg/dl, 296.5 mg/dl, 4.610 mg/dl, 2.837 mg/dl, 1.028 mg/dl, 102.0µl, 643.667µl and 0.508 mg/dl, respectively (Table 2).

In 30 days exposed fishes, the recorded values of plasma glucose, cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, total protein, serum bilirubin, serum creatinine, SGPT, SGOT and lipid peroxidation were 52.935 mg/dl, 186.617 mg/dl, 151.333 mg/dl, 297.667 mg/dl, 4.512 mg/dl, 3.658 mg/dl, 1.32 mg/dl, 109.667µl, 691.33 µl, and 0.452mg/dl, respectively (Table 2).

In 45 days exposed fishes, the recorded values of plasma glucose, cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, total protein, serum bilirubin, serum creatinine, SGPT, SGOT and lipid peroxidation were 41.94 mg/dl, 221.417 mg/dl, 170.5 mg/dl, 301.167 mg/dl, 4.433 mg/dl, 3.442 mg/dl, 1.67 mg/dl, 110.467µl, 757.167 µl, and 0.40mg/dl, respectively (Table 2).

Thus, the exposure of dichlorovos to Channa gachua led to increase in cholesterol, alkaline phosphatase in plasma, triglyceride in plasma, serum bilirubin, serum creatinine, SGPT and SGOT parameters, in both acute and chronic studies. It is evident from the results that the sub-lethal concentration of dichlorovos has influence on various biochemical parameters in exposed fishes.

Figure 2

Table - 2. Sub-lethal effect of Dichlorovos on certain biochemical parameters of (Ham.) - Chronic Studies (0.012mg/l)

A sizeable amount of organophosphatases have been used to boost up agricultural yield. The run-offs from treated lands are known to interfere with nutrio-economically important animal and growth in water bodies by altering and disrupting the different physiological processes.

Gopal et al., (Gopal et al., 1985) studied neuro behavioral changes in fresh water fish, Channa punctatus exposed to endosulphan. Mukhopadhyay and Dehadrai (1980b) observed a marked decline in liver glycogen and protein contents in the catfish with sub-lethal concentration of malathion. Sastry and Sharma (1981) and Singh and Shrivastava (1982) studied in various carbohydrate metabolites in Ophiocephalus punctatus and Heteropneustes fossilis treated to toxicants. Mukhopadhyay and Dehadrai (1980b, 1980a) noticed various biochemical changes such as SGOT and SGPT in the air-breathing catfish, Clarias batrachus under sub-lethal malathion exposure. Murthy and Devi (1982) reported decreased level of protein, glycogen and lipid concentration in liver and increased level in brain of Channa punctatus.

Joshi and Desai (1981) investigated sub-lethal concentration of monocrotophos on acid and alkaline phosphatase activity in the tissue of freshwater fish, Tilapa mossambica. Shrivastava and Shrivastava (1984) reported alterations in blood glucose values in Hereropneustes fosilis to sub-lethal concentration of chlordane for 15, 30, 50 and 70 days. Sastry and Dasgupta (1991) noticed significant alterations in blood glucose, lactic acid and protein in Clarias batrachus, Anguilla anguilla and Channa pnctatus acutely or chronically exposed to aldrin, lindane and nuvacron. Singh and Shrivastava (1982) have noticed hyperglycemia in Hereropneustes fosilis treated with sub-lethal concentrations of organphosphate insecticides.

In the present study, it has been observed that the exposure of dichlorovos led to the decrease in the level of plasma glucose, total protein, and lipid peroxidation while significant increases was observed in the levels of cholesterol, alkaline phosphatase In plasma, triglyceride in plasma, serum bilirubin, serum creatinine, SGPT and SGOT. Similar results were also noticed by Murthy and Devi (1982), Borah and Yadav (1995), Katti and Sathyanesan (1983), Ram and Sathyanesan (1984, 1985) Dalela et al., (1978), Agrahar and Bhartiya (2004), Santhakumar and Balaji (2000, 1999), Tilak et al., (2003, 2001) and Sharad Srivastava et al., (1990).