I don't believe it's a tilapia of any kind, but it does look like it will get big. My guess is that it will get at least a foot long and a lot bulkier. I would say it will need at least a 120 gallon aquarium. I don't know what fish this is, though. I'm just going on my gut feeling when looking at the pictures. It has a big head, big mouth and large tail fin. Those are signs that say to me that it will be a large fish.