would are the dimensions? an aquarium that large could sustain the chameleon quite well with some modifications (side vents, false-bottom drain system)
some things TO CONSIDER:
What species of chameleon are you planning to house?
do they need to thrive off of high humidity?
are you going to live plant it as a terrarium?
will your chameleon go and try and eat dirt, or any other substrates or decors?