absolutely nothing, im sure its a great deal but when you buy a tank thats really tall and not wide, you are limiting what you can put in it. For example in a 4 foot long tank you can have boesmani rainbowfish because they have the space to swim back and forth, but if I am correct about hex's, you cant have fast swimming space loving fish even if the tank can fit the same amount of h20. Get it? Something like an Angelfish would be great in a tank like a Hex.