In September 2021, Natel conducted formal testing with PNNL on a cohort of American eel passing through the RHT test unit operating at 670 rpm under 10 m of hydraulic head. Following the test the eels were monitored for 48 hours with 100% survival.
This article from the Water Power Technologies Office includes a photograph of Natel's technology and encourages the adoption of turbines that are safe for fish to pass through.