Effects of heavy metals on fish physiology - A review.

The pollution by heavy metals poses a serious threat to the aquatic environment and to the organisms if the concentration of heavy metals in the environment exceeds the safe limits. Due to their non-biodegradable and long persistence nature in the environment, heavy metals cause toxicity in fish by producing oxygen reactive species through oxidizing radical production. In this review, we investigated the effects of heavy metals on fish physiology with special emphasis on hemato-biochemical properties, immunological parameters especially hormones and enzymes, histopathology of different major organs and underlying molecular mechanisms.

Toxic effects of fenitrothion on freshwater microcosms in Bangladesh.

The organophosphate pesticide fenitrothion is widely used as an agricultural pesticide to control tiger bug in larval rearing for aquaculture. The objectives of the present study were to assess the effects of fenitrothion on certain structural (phytoplankton, zooplankton, macro-invertebrates and periphyton) and functional (organic matter decomposition) endpoints of freshwater microcosms. Fenitrothion 50 EC was applied in 12 microcosms (PVC tanks having 400 L of dechlorinated tap water) providing concentrations of 0, 25, 50 and 100 μg/L at a 4-day interval over a period of 4 weeks.

Toxicity of the organophosphate insecticide sumithion to embryo and larvae of zebrafish.

Sumithion, a synthetic organophosphate, is widely used as an agricultural insecticide and for control of tiger bug ( spp.) in larval rearing for aquaculture. An experiment was conducted to examine the effects of sumithion on embryological and larval development of zebrafish .

Thermal stress causes nuclear and cellular abnormalities of peripheral erythrocytes in Indian major carp, rohu Labeo rohita.

Rise of water temperature as a consequence of global warming is anticipated to affect the physiological activities of fish, especially in tropical regions. In the present experiment, we exposed the Indian major carp, rohu Labeo rohita to three different temperature regimes (30 °C as control and 33 °C and 36 °C) for 60 days and observed the effects of these temperature on: major hemato-biochemical indices (Hemoglobin; Hb, Red blood cell; RBC, White blood cell; WBC and blood glucose levels), erythrocytic nuclear abnormalities (ENA), and erythrocytic cellular abnormalities (ECA) of peripheral erythrocytes along with the formation of differential leucocytes in the blood. Fish were sacrificed at day 7, 15, 30 and 60 after the start of exposure to the temperature regimes.

Increase in water temperature increases acute toxicity of sumithion causing nuclear and cellular abnormalities in peripheral erythrocytes of zebrafish Danio rerio.

Global warming and indiscriminate usages of pesticides are notable concern to all. The present study has been conducted to evaluate the effects of high temperature on acute toxicity of sumithion in adult zebrafish. A 2-day renewal bioassay system was used to determine the 96 h LC value of sumithion at three temperature regimes, such as 25 °C, 30 °C, and 35 °C.