Toxicological assessment of cannabidiol (CBD) in Koi carp (Cyprinus rubrofuscus): Dose-dependent effects on hematological profiles, serum biochemistry, and multi-organ histopathology https://doi.org/10.12982/VIS.2026.088
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Abstract
Despite growing interest in phytogenic additives in aquaculture, the toxicological profile of cannabidiol (CBD) in teleost fish remains poorly characterized, with existing data limited to acute embryotoxicity and behavioral endpoints in zebrafish. This study aimed to conduct a systematic, dose-dependent toxicological assessment of dietary CBD in Koi carp (Cyprinus rubrofuscus), evaluating hematological, serum biochemical, and multi-organ histopathological responses following 28-day sub-chronic exposure. One hundred thirty-five Koi carp (24.0 ± 2.2 g) were randomly assigned to six dietary groups: feed control, vehicle control (soybean oil), and four CBD-supplemented groups (0.001%, 0.01%, 0.1%, and 1%) for 28 days. CBD isolate was incorporated via soybean oil carrier. Low-dose exposure (0.001% feed) enhanced erythropoiesis without adverse effects. Splenic melanomacrophage centre proliferation emerged at 0.01% feed, representing the most sensitive histopathological endpoint. Hepatic vacuolar degeneration and elevated serum AST occurred at 0.1% feed, progressing to multi-organ necrosis at 1% feed. Serum cholesterol was elevated across all CBD concentrations. A dietary NOAEL of 0.001% feed and LOAEL of 0.01% feed are established for ornamental cyprinid aquaculture, with the spleen and liver identified as principal target organs.
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