Abstract

Growth of Cherax albidus Clark (mean initial weight 0.228 - 0.249 g, stocking rate 67 m^-2) at mean unionised ammmonia concentrations of 0.008 (control), 0.096, 0.490, 1.030, 1.550, and 2.040 mg L^-1 was monitored at a pH of 8 over a 65 day period. Unionised ammonia concentrations were established using ammonium chloride and pH was controlled using a sodium carbonate/sodium hydroxide buffer system. Mean final weight of animals was significantly less than that of controls at all experimental unionised ammonia concentrations. A significant difference in weight between control and animals reared in 0.096 mg L^-1 unionised ammonia was detected after 14 days. Mean growth rates during the experimental period were 0.241 g day^-1 in control animals, and 0.170, 0.088, 0.033, 0.013, and 0.005 g day^-1 respectively in increasing ammonia concentrations. Total mortality during the experimental period was similar (57-67%) across all control and ammonia treatments. There was no significant increase in moult frequency across all treatments. Reduced growth rates at unionised ammonia levels above 0.096 mg L^-1 appeared to result from reduced moult increment. A "safe" level of 0.05 mg L^-1 unionised ammonia is recommended for C. albidus culture.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: