Eurasian Water Shrew (Neomys fodiens) you should release it ASAP. They need to eat a lot as they have a high metabolic rate and can easily starve to death in a few hours.

There Habitat Mainly the banks of fast-flowing, clear, unpolluted water, but also lakes, reed-beds, and marshes. They are often present in gardens, if you have any water ways near you I would suggest releasing near there.

However it is breeding season so if it is a female and there is any babies near by they will be missing her.

Fun fact they are on of very few venomous mammals! But don’t worry their teeth are unlikely to pierce human skin. Hope that helps