Your tiger should grow to full size with in an 12-16 month period. How large, some can get to be quite big, 14" is possible, however there is wide spectrum of sizes, I would say atl east 9". As for food, O's love a varied diet. Pellets, bloodworm, beafheart, krill, earthworms, shrimp, a lot of insects, from my experence, anything that will fit in their mouths...lol. If you take care of their enviroment for them, since they are unable to do anything but put up with the water quality you give them, feed them well, but not too much. Then you will have a healthy and happy fish.