You have that big thing called the Caspian Sea there
However, as already stated, the fish tend to be rather "tainted" by some nasty things.
There are meant to be carp in some of the parks, and there is a sort of canal that runs through one of them which my partner said she saw some "big brown fish with big scales" swimming about...I take them to be carp as well.
The good news though is that there is a trout, Salmo Trutta Caspius, which is basically a Sea Trout in appearance and habit. I think I am right in saying they are not as subtle as UK sea trout in that they are very predator and feed mainly on fish and crustaceans. Because of this they get to silly sizes...20kg+
Hope that helps a little...I will see what my partner can find out when she is out there next week. She is an environmental chemist and has access to lots of data reguarding fish and things