Unraveling florfenicol's effects on splenic histology, erythrocytes, and hematology of healthy Oreochromis niloticus juveniles

The study aimed to investigate the impact of administering the antibiotic florfenicol (FFC) through dietary means on Oreochromis niloticus. The experiment involved exposing the fish to FFC at doses 0–10 times the therapeutic dose of 15 mg/kg biomass per day for 10 consecutive days. The group receiving the therapeutic dose showed 100% survival on the 10th day of dosing. Histological analysis revealed dose-dependent changes in the spleen, including an increase in sinusoidal space, splenic necrosis, white pulp proliferation, splenitis, and red pulp hemorrhages. Additionally, there was an exponential rise in leukocyte counts accompanied by a significant decrease in erythrocyte counts, indicating the development of anemia due to FFC. The observed splenic histological damage, along with increased erythrophagia, erythro-membrane breakage, and poikilocytosis, highlighted the splenotoxic and hemotoxic effects of FFC at higher doses. Importantly, these toxic effects showed considerable reduction upon discontinuation of FFC dosing. The study emphasized the need to consider FFC-induced splenotoxic and hemotoxic outcomes in O. niloticus during its application in aquaculture.