A Neptune fish guidance system installed in the backwater prevents fish from getting into turbines by reversing their migration direction or ensuring a safe descent through fish passes.
A Neptune fish guidance system installed in the tailwater prevents ascending fish from swimming into the strong-flowing, oxygen-rich turbine outlets and guides them into fish passes.
The Neptune fish guidance system helps ensure the ecological connectivity of running waters required by the Water Framework Directive (WFD), prevent animal suffering and reduce damage to power plant facilities.
Above-ground water collection
The Neptune Fish Guidance System protects technical facilities that need to collect water from water bodies above ground for cooling power plants or for the extraction of process water. Many animals die in pumps. With a lot of effort, water extraction plants have to be cleaned. The Neptun Fish Guidance System protects fish and plants.
Protection of water bodies
The Neptune system can also be used as a migration barrier. This can prevent invasive species from entering sensitive aquatic ecosystems or protect fish farms from predators.

This technique has been used for decades, although in the opposite direction, in electrofishing for stock assessment and regulation as well as evacuation, where it has proven to be a reliable method.
Required data for planning:
- Construction plans of the plant with positions of turbines, fish pass, or water supply points
- Water depth
- Conductivity
- Condition of the water bottom
- Flow velocity
- Position of the power supply for the NEPTUN system (optimal: three-phase connection)
NEPTUN can be used not only as a fixed installation in a plant but also as a portable version.
Brazil
Hydropower plant at the Madeira, Jirau
Canada
Diversion of migrating sea lamprey in fish traps, Bridgeland Creek (portable NEPTUN)
Fish barrier in Lake Ontario
Germany
Fish protection nuclear power plant Philipsburg, Rhine
Fish protection waterpower plant Gaggenau, Murg
Fish protection waterpower plant Mühlhausen, Enz
Fish protection water intake Wiesbaden, Rhine
Poland
Hydropower plant at Widawka, Szczerców
Hydropower plant at the Drzewiczka, Drzewica
Hydropower plant on the Wisłok, Rzeszów
Hydropower plant on the Odra river, Kędzierzyn Koźle
Hydropower plant on the Wisła, Smolice
Monitoring of the effects of the "Plan of development of eels in Poland" (portable NEPTUN system).
Dam in the Bóbr, Krzywaniec
Switzerland
Hydropower plant in Lake Geneva, Veytaux
USA
Fishways Global
Diversion of migrating sea lamprey in fish traps, Hammond Bay Biological Station, USGS, Great Lakes Science Center, Millersburg (portable NEPTUN)
Diversion of migrating sea lamprey in fish traps, Silver Creek River, Ocqueoc River, Michigan (portable NEPTUN).
Further information is available here.