ok heres what you do. I have a 125 that will be a future tank. You have to think about what your looking for. Do you want aggression or do you want to watch fish swim peacefully? If you want aggression then you go with a jag, dovii, red devil, or a pike. 125 would be a great tank for these fish to have a mate in for life and you could make a lil money selling the babies. If you dont want that then you could do any of those fish plus an aggressive bottom feeding fish although this may not workout. You could also do a wolf fish and some cichlids with supervision of course. If you want beaceful then you do schooling fish. Some redhook silver dollars or basic silver dollars then you just add some peaceful tankmates.