Toxic Effects of Waterborne Nitrite on LC50, Hematological Parameters, and Plasma Biochemistry in Starry Flounder (Platichthys stellatus).

Nitrite is a common environmental pollutant in aquaculture systems, where high levels can severely impair fish physiology and survival. This study aimed to evaluate the acute toxicity of waterborne nitrite in starry flounder (Platichthys stellatus). Fish (mean weight 145.69 ± 16.06 g, mean total length 22.78 ± 0.70 cm) were exposed to nitrite concentrations of 0, 25, 50, 100, 200, 400, and 800 mg NO₂^-/L for 96 h. The lethal concentration 50 (LC₅₀) of nitrite for P. stellatus was determined to be 574.47 mg NO₂^-/L. Hematological parameters such as red blood cell counts (RBCs), hemoglobin (Hb), and hematocrit (Hct) were significantly decreased by nitrite exposure. Plasma components including calcium (Ca²⁺), glucose, cholesterol, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were significantly changed by nitrite exposure. The results of this study suggest that acute exposure to waterborne nitrite (>200 mg NO₂^-/L) adversely affects survival rates, hematological parameters, and plasma components in P. stellatus. These findings provide important baseline data for nitrite toxicity assessment in P. stellatus.