Yes it will most definetly work for river bass. On my first trip of the season earlier this week I had a good deal of success with it (on a river). In fact it was the only bait that put fish in the boat. As far as size goes the 4 1/2 should work just fine I caught fish in the range of 1-3 pounds on it. I had more success throwing against the current and bringing the bait back upstream slow rolling it just enough to keep the tail moving. Its a great bait at a good price but lacks durability they rip up pretty easily.