Available knowledge on the sichel, Pelecus cultratus, from the middle Danube River and its tributaries is insufficient. This study aims to provide new data on the morphology and ecology of sichel from the Mur River, and its distribution in Croatia and Slovenia. In 2009, the schooling of sichel were observed at a high-water level in the Mur River of Slovenia. In total, 14 specimens were sampled by fishermen using sport fishing techniques. The age, condition, length-weight relationship (LWR), 20 morphometric and four meristic traits, were analysed. Fulton condition coefficient and LWR value indicated that sichel specimens' were well adapted to the environmental conditions. Positive allometry in both males and females were observed (W = 0.004 L 3.119 ). This represents the first LWR dataset for sichel. The morphometric and meristic traits values from this research add to the limited data that is presently available. By comparing historical and recent data on sichel distribution, we observed a dramatically declining trend. Therefore, further research and targeted protection of the sichel in the middle Danube River tributaries are urgently required.