TitleAcute and sublethal growth effects of un-ionized ammonia to nile tilapia Oreochromis niloticus
Publication TypeConference Paper
Year of Publication1998
AuthorsAbdalla, AAF, McNabb, CD
EditorRandall, D, MacKinlay, D
Conference NameNitrogen Production and Excretion in Fish, Symposium Proceedings of the International Congress on the Biology of Fish
Date Published1998
PublisherAmerican Fisheries Society
Abstract

This study investigated the acute effects of un-ionized ammonia (NH3-N) on 11 g fingerlings of Nile tilapia Oreochromis niloticus at two temperatures (23 and 33°C); and at 28 degrees C with two sizes of fish, 3 and 45 g. In addition, sublethal effects of un-ionized ammonia on.growth of Nile tilapia at 28 degrees C were evaluated. All tests were conducted in flow-through bioassay system.

In acute toxicity tests at 23 and 33°C, the 96-h LC50's (±SD) were 2.25 ± 0.07 and 2.51 ± 0.16 mg/L NH3 -N, respectively. There was not a significant effect between the two temperatures on acute toxicity of NH3- N in these tests (P 0.05). Estimates of the 96-h LC50's (±SD) at 28°C were 1.36 ± 0.45 mg/L NH3-N for the small fish and 2.65 ± 0.09 mg/L NH3-N for the large fish. In these tests, there was a significant difference between the two sizes of fish tested (P 0.05). In 35-day study of the effects of sublethal concentrations of NH3-N at 28°C, there was a linear decrease in fish weight gain with increasing un-ionized ammonia concentrations (r2 = 0.90, P 0.001). The concentrations of un-ionized ammonia that cause no reduction in growth, 50% reduction in growth, and 100% reduction in growth were 0.06, 0.73, and 1.46 mg/L NH3-N, respectively. These data suggest that Nile tilapia has a tolerance to un- ionized ammonia similar to that of tilapia species, somewhat greater than that of channel catfish, and greater than that of many other warmwater fish and salmonids.
URLhttp://fishphysiology.org/wp-content/uploads/2014/02/Nitroint.pdf
Notice of Publication Number

NOP 98-125 (English) (Spanish)