Survival of diploid and triploid Rhamdia quelen juveniles in different ammonia concentrations

Triploidy is a common chromosomic manipulation technique used in fish culture to eliminate gonadal maturation and also to obtain other advantages. However, studies demonstrate that triploid fish exhibit some structural differences in the central nervous system and sensory organs, suggesting distinct behavioral or physiological responses to the environment when compared to diploid fish. The objective of this study was to determine the lethal concentration of ammonia nitrogen (NH 3–N) over 96 h of exposure (LC50-96h) for diploid and triploid jundiá Rhamdia quelen juveniles. Diploid and triploid fish weighing approximately 10 g were subjected to NH 3–N concentrations varying between 0.8 and 3.4 mg L − 1 NH 3–N; the dissolved oxygen concentration remained saturated, with a pH of 8 and a water temperature of 25 °C. The LC50 for the diploid fish was 2.99; 2.26; 2.00 and 1.91 mg L − 1 NH 3–N and for triploid 2.39; 2.03; 1.96 and 1.91 mg L − 1 NH 3–N, in 24, 48, 72 and 96 h, respectively. The results indicate a greater sensitivity of triploid fish in the first 48 h of exposure to ammonia than of diploid ones; however, the tolerance of the ammonia for triploid fish increased with exposure time, and the accumulated mortality value became similar between both ploidies after 96 h of exposure.