I'm not saying to keep fish in small tanks but I have the 14" pink midas hybrid in a 60gallon which is only a 3' tank and the tank is adequate for him. If that's the only tank you have I'd say go for it you will not regret getting a flowerhorn. If you feel bad keeping a flowerhorn in there why not try a nice female? It probably won't get as big or have nearly as much girth as a male anyways.