Relative Sensitivity of Chinese Carps (Ctenopharyngodon Idella and Hypophthalmichthys Molitrix) to Acute Exposure of Metals Mixtures

S. Naz and M. Javed

Department of Zoology and Fisheries, University of Agriculture, Faisalabad, Pakistan

ABSTRACT

The present study was conducted to measure acute toxicity (96-hr LC50 and lethal concentrations) of water-borne metals mixture (zinc, iron, nickel, lead and manganese) on two fish species, Ctenopharyngodon idella and Hypophthalmichthys molitrix at constant pH (7), water temperature (30°C) and total hardness (200mgL-1).  The two fish species demonstrated inconsistent tolerance limits, while concerning 96-hr LC50 and lethal concentrations against 19 mixtures of five metals. The mixture of five metals (Fe+Zn+Pb+Ni+Mn) caused significantly higher toxicity to the fish, with lethal concentrations of 41.81±14.93 and 69.10±15.22 mgL-1(96 hr LC50), respectively. However, least toxicity to the fish was caused by Zn+Ni and Zn+Pb mixtures, with the mean LC50 and lethal concentrations of 81.92±7.75 and 134.45±31.79 mgL-1, respectively. Regarding overall sensitivity of two fish species, Ctenopharyngodon idella depicted least sensitivity to metals mixtures with a mean LC50 and lethal concentrations of 77.86±13.90 and 122.40±23.74 mgL-1, respectively. Ctenopharyngodon idella was less sensitive to metal mixtures compared to Hypophthalmichthys molitrix in the present study.
Key words: LC50, Lethal concentrations, Metals mixtures, Ctenopharyngodon idella, Hypophthalmichthys molitrix.