Alpha,
They fight like a 'gill...though the big one did rip drag on 4# line, and I had two break me off. Some are fairly tame, others are much more energetic. The 7"-9" ones are abundant, and they fight ok at best, anything over 10" feels almost like a decent shellcracker. Bigger than that and they will give you a tussle. I was using a med power rod, so I imagine an UL would be great.
I'm assuming they escaped ponds during the flood. They are stocked for weed control, food, and as prey for bass. The ones I'm catching are blue tilapia, and a pure strain blue can tolerate water temps down to 47 degrees. I called TWRA about it, and they know the tilapia are in old hick, but I didn't get much more info from them. I researched them a lot after I caught one lady Sunday, then I tried some of my theories out on Thursday, and by Saturday I had a good handle on things. Looks like they are going to survive in the lake, which means my short list of fish I'll take home just grew by one species
Chris