Since I have the Tiger Oscar,pleco,and Jack Dempsey in the tank.Is it possible to fit just one more fish into the 55 gallon,I am thinking,if I did this,in the near future,I was going to shop for a 100 gallon or above(just a estimate).I was looking at Green Terrors.Oh before anyone saids anything about my 55 gallon being too small,I do have a extra spare 30 gallon outside,that isn't being used.This is just a thought,not a 100% sure at the moment. 