Toxic effects on hematological parameters and antioxidant enzymes in Far Eastern catfish, Silurus asotus depending on the exposure to nano and micro silver particles size

The increasing use of silver nanoparticles (AgNPs) has raised concerns about their ecotoxicological effects on aquatic organisms. This study assessed the toxic impact of AgNPs and silver microparticles (AgMPs) on hematological parameters and antioxidant enzymes in Far Eastern catfish, Silurus asotus. Experimental fish, S. asotus (mean weight, 95.6 ± 33.0 g; mean length, 25.5 ± 2.4 cm) were exposed to AgNPs (0, 4, 8, 64, 128 mg/L) and AgMPs (0, 4, 8, 64, 128, 256, 512 mg/L) for 10 days. Hematocrit (Hct) decreased in both AgNPs- and AgMPs-exposed groups, while hemoglobin (Hb) decreased with AgNPs exposure but increased with AgMPs. Plasma calcium (Ca) increased with AgNPs but decreased with AgMPs, whereas magnesium (Mg) showed an initial increase at day 5 followed by a decrease with AgNPs and a continuous decrease with AgMPs. Plasma glucose (Glu) and cholesterol (Cho) levels increased, while total protein (TP) decreased. Plasma enzyme activity (AST, ALT, ALP) was increased in all exposure groups. Antioxidant responses showed significant changes, with superoxide dismutase (SOD) increasing in gills and liver under both AgNPs and AgMPs exposure. Catalase (CAT) increased in both tissues with AgNPs, while AgMPs led to decreased activity in gills but increased levels in the liver. These findings highlight the particle size-dependent toxicity of silver, emphasizing potential risks to aquatic organisms.