Abstract
Experiments were conducted to establish the lethal dose concentration of un-ionized ammonia at which 50% and 100% mortality of fingerlings of Ctenopharyngodon idella (Valenciennes) occurred. Fingerlings of C. idella were obtained from Central Fish Seed Hatchery, Lahore and were stocked in 300 liters cemented indoor rectangular tanks. The tanks were supplied tube-well water (temperature 13-19 0 C, pH 7.9- 8.8; hardness 276-344 mg/l as CaCO3, dissolved oxygen 5.0-8.1ppm with zero total ammonia nitrogen. Fingerlings were fed daily with standard fish feed. Median lethal concentrations (LC50) were determined in glass
aquaria each containing 9 fish (mean weight 12.7±1.4 to 7.2±1.31g) and
40 liters of test water. Total ammonia-N concentration was determined by direct Nesslerization. The 24 hour LC50 of un-ionized ammonia for C.
idella fingerlings (mean body weight 2.50 ± 1.54g, at 15±0.10 C and pH 8.0 ± 0.01) was 0.05mg/l. Lethal dose of un-ionized ammonia at which
100% C. idella fingerlings (mean body weight 2.96 ±0.8g, at 15±0.10
C and pH 8.12 ± 0.02) showed mortality, was 0.075mg/l. Fish under
experiment remained unharmed when ammonia concentration was 0.025 mg/l.
NASREEN IJAZ , ZAFAR IQBAL , JAMIL ANWAR CHAUDHRY. (2011) TOXICITY OF AMMONIA TO FINGERLING GRASS CARP, CTENOPHARYNGODON IDELLA (VALENCIENNES) , Punjab University Journal of Zoology, Volume 26, Issue 1.
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