Restoring the longitudinal connectivity of watercourses must be a priority for both river managers and policy makers. The abundance of transversal hydrotechnical constructions along the watercourses including natural reserves, as is the case of the discharge sill located on the Bistra Marului River, creates existential problems for local aquatic life and the migratory species the same. None of the the Bistra Mărului River discharge sills have fish migration systems. The Water Framework Directive of the European Union allocates important chapters of both legislation and implementation regarding the protection of the lotic ecosystems including the restoration of the longitudinal connectivity. Structural and functional redevelopment through the technical improvement of existing fish systems and the development of new practical designs will in particular bring new hope for migratory fish species as well as ecological stability for local ones. The River system supports a diverse fish community with many migratory species, some potamodromous and some diadromous. So there are significant challenges in attempting to design a system that passes the majority of fish from a diverse range of size classes. The complementarity between the solutions proposed in this presentation will provide an efficient logistic support for the builders of the migration system on the Bistra Mărului River located in Caraș Severin County, România, the European Union. There is currently no fish pass construction program in Romania and there is an urgent need to develop solutions which will benefit all species and are simple for managers to install and implement.