not many people keep them due to the fact they are not one of the easiest fish to keep, they can be hard to feed, prone to disease, need different water requirements, get very large, and tend to eat anything that fits in their mouth, and they also arent one of the "prettiest" fish out there, i loved mine, and he was very cool to watch. but..... mine rarely ever ate, was always hiding, and ate4 a pebble and died from it, so they arent too intelligent either, and YES you will need a larger tank when he gets full grown, and this is just an assumption but i would say it takes them about 2 years to reach full length, mine grew 2-3 inches in about 6 months and he was about 7-8 inches when he died.