it will work. I had a jack dempsey 9" texas 11" and a nice jag who was the baby of the tank 7.5". It will work, 75 is eeh 85 would be better but you can still give it an try, worst that would hanppen is that it wont grow out full size. Go for it i say. but then again some people really have problems when somebody puts a fish in a smaller tank. 75 is good.