Acute ammonia toxicity during early ontogeny of chub, Leuciscus cephalus (Cyprinidae)

Abstract

Acute toxicity of ammonia was investigated in four life stages of juvenile chub, Leuciscus cephalus (cyprinid fish): 1, 10, 20 and 30 days after the first feeding. The fish used for the toxicity test were reared intensively in a closed recirculation system. Each acute toxicity test duration was 96 h and lethal concentration LC 1, LC 50 and LC 99 values were calculated for 24, 48, 72 and 96 h. The susceptibility of chub to acute ammonia toxicity decreased linearly with age and stage of development. The LC 50 (48 h) values ranged from 0.62 mg L -1 of unionized ammonia nitrogen for one day after first feeding larvae to 1.73 mg L -1 for 30 days after first feeding ones. A significant linear relationship between chub larvae susceptibility to ammonia toxicity and both body weight and length was found. The critical level of unionized ammonia nitrogen for chub larvae was suggested as 0.49 mg L -1. © EDP Sciences, IFREMER, IRD 2011.