Pakistan J. Zool., vol. 47 (4), pp. 913-919, 2015. Effect of Various Doses of Cr (VI) on Survival and Growth of Cyprinus carpio Tayybah Shaheen 1 and Farhat Jabeen* 2 1 Government College for women Karkhana Bazar Faisalabad, Pakistan 2 Department of Zoology, Government College University, Faisalabad, Pakistan Abstract.- This study assessed the impact of different doses of hexavalent chromium [(Cr (VI)] on survival and growth of Cyprinus carpio. It was investigated that Cr (VI) adversely affected the survival and growth of Cyprinus carpio in temporal dose pattern through ambient water. Fish refused to accept the feed immediately after the exposure but after 6 to 7 hours it began to take feed. In this study it was revealed that Cr (VI) exposure significantly altered several physicochemical variables of the water: Cr (VI) increased BOD, COD, CO2, alkalinity, calcium, hardness, chlorides, TDS and turbidity whereas, pH and DO were decreased on Cr (VI) exposure. Growth decreased significantly with the increase in Cr (VI) concentration and the rate of decline in length (24%) was less than weight (51%). Mortality was 40% in exposed fish. Actual chromium concentration in tanks varied from 36 to 118µg/ml exposed with 25 to 150mg/l of Cr (VI). Exposure of fish to different chromium concentrations in water significantly (P<0.05) reduced their feed consumption and specific growth rate as compared to control. This decrease was linearly correlated with the increase in chromium concentration. Key words: Physicochemical parameters survival growth mortality ambient water. INTRODUCTION Fish is an important source of animal protein. Its nutritional value is very high not only for normal human requirements but also for prevention of many metabolic ailments and cardiac troubles (Lemos et al., 2005). However the fish habitats are being contaminated alarmingly through a number of aquatic pollutants (Charles et al., 2006; Oner et al., 2009). These pollutants have not only depleted the fish stock in a number of water bodies but also have threatened the human health by incorporating into food chain. Among these pollutants heavy metals are most injurious for fish life. Metal pollution has curtailed fish production and resultantly the human population is facing a great shortage of aquatic animal protein (Lu et al., 2015). Therefore, it is necessary to control the use of heavy metals because they are posing hazardous impacts to aquatic fauna which ultimately leads to serious human health concern (Ambreen et al., 2015). Biological interest in chromium (Cr) has risen due to its prominent role in industrial pollution and toxicity. Cr exists primarily in Cr (III) and Cr (VI) ______________________________ * Corresponding author: farjabeen2004@yahoo.co.in 0030-9923/2015/0004-0913 $ 8.00/0 Copyright 2015 Zoological Society of Pakistan. oxidation states; the later, hexavalent species, being considered as more toxic in the environment due to its higher solubility and mobility. These species are known to be associated with a spectrum of DNA lesions occurring during Cr (VI) exposure (Reynolds et al., 2004). Though in small traces it played an important role in growth (Tylor, 1999) and metabolism yet at higher concentration (250- 300 mg/l for freshwater fish), Cr is highly toxic, mutagenic (Jim et al., 2006; Laura et al., 2006), carcinogenic (Singh et al., 2005; Prabakaran et al., 2006), teratogenic (Krishnani et al., 2006; Mokhtar et al., 2006), and highly mobile and incorporating metal (food chain) (Vinodhini and Narayanan, 2009). The effect of Cr (VI) on survival of fish in term of LC50 has been investigated from 142-250 mg/l for freshwater fish. This variation in LC50 depends on size, species, source of chromium (VI) and physical conditions i.e. temperature, pH, and DO etc. (Mishra and Mohanti, 2009). Cr has detrimental effect on fish growth and survival (Shaheen et al., 2012). It has not only damaged fish fertility but also produced defects in progeny. Exposure of breeders before spawning induced cumulative effect on gonads which in turn produced weak, meager and retarded offsprings due to malfunctioning of trophic hormones (Kobayashi and Okamura, 2005; Imai and Nakamura, 2006).