In your picture because the snails were darkened due to being wet, I probably gave a wrong ID. (Plus for some reason I associated the river to a COMPLETELY different region) lol
Upon reviewing some scientific reports, they're probably one of the many melanopsids present in that European region. They're sub-tropical snails like the JMS I ID'd earlier.
I have no other knowledge of the region, but I'm sure if the snails were thriving in that region, just take some tests/samples of their environment (pH, GH, KH, etc...) Take note of the substrate as well.
Most wild caught snails when placed in captivity thrive and grow fast but due to not going through an aestivation period like they would in the wild, they "burn out" and die sooner.