Vol. 9, Issue 11, Part F (2025)

The zebrafish (Danio rerio) embryo model provides a robust and ethically viable platform for evaluating developmental and acute toxicity due to its genetic and physiological homology with higher vertebrates. Krill oil, derived from Euphausia superba, is a marine lipid source rich in phospholipid-bound omega-3 fatty acids (EPA and DHA) and antioxidant astaxanthin, widely promoted for cardiovascular and anti-inflammatory benefits. However, its embryotoxic potential remains insufficiently characterized. The present study assessed the developmental and cardio-physiological effects of krill oil exposure in zebrafish embryos following the OECD Test Guideline 236. Fertilized embryos were exposed to varying concentrations of krill oil (0.125-1.0 µL/mL), alongside water and DMSO controls, and evaluated for viability, hatching rate, morphological deformities, and heart rate at 24-, 48-, 72-, and 96-hours post-fertilization (hpf). Embryo survival exceeded 85% up to 0.25 µL/mL and declined modestly at higher concentrations, indicating minimal acute lethality. Hatching success was comparable to controls, with a slight, transient delay at the highest exposure. Morphological abnormalities such as curved body axis and mild yolk sac edema were sporadic and confined to upper dose groups, while pericardial edema was absent. Heart rate showed a marginal, statistically insignificant decrease (from 164±15.5 bpm in controls to 152±13.1 bpm at 1 µL/mL). Overall, krill oil exhibited a broad safety margin and negligible developmental or cardiac toxicity at physiologically relevant concentrations. The zebrafish embryo assay thus validates the low embryotoxic potential of krill oil and its safety profile.