Millers thumb fish

[Rach88]

That is a invasive species of goby they eat trout eggs just kill it they have them in Canada too and they are an invasive species

These fish are native here in the UK. And they aren't gobies they're a type of sculpin
http://www.arkive.org/bullhead/cottus-gobio/#text=All

 

[Ryleyman]

What ever

 

[alLexX]

it does kinda look like a roundhead "goby",theyre invasive but make pretty cool pets. i kep a couple in a tub of water for a while,they were interesting