Don't bother with under 300 gallons if you are serious. The fish gets anywhere from 24-26" full grown, and it doesn't take long for them to put on serious size. They also have tremendous depth and girth, as well as an enormous amount of power (can break thin glass). The red-finned giant gourami will top out at around 20", and you need a minimum of a 6' 150 gallon for him alone! Great fish, I used to care for them years ago at a place I worked, there were two in a 240 and it was a little tight for full grown specimens. Not a fish for someone with limited space, they will outgrow most home aquariums within 2-3 years. I had to pass on a beautiful gold(pink) giant gourami for $30 because I only have a 75 gallon, and ultimately, I know it will outgrow it too soon.