A simple osmium post-fixation paraffin-embedment technique to identify lipid accumulation in fish liver using medaka (Oryzias latipes) eggs and eleutheroembryos as lipid rich models

► Hepatic lipidosis in fish liver is often misdiagnosed or overlooked. ► Specific histological fat stains and cryostat sections are not commonly used. ► Standard paraffin processing removes lipid leaving vacuoles of unknown origin. ► Osmium post-fixed paraffin-embedment is a cost effective alternative. ► Medaka trials show suitability for lipid visualization in tissues from egg to adult.