I house my female bamboo, female White spotted bamboo and male coral cat in the same tank with no problems. They all hang out together and swim together.
i know this is always a concern but, they are currently in a 6x2x2 with room to grow. i also have a 300g rubbermaid when the time comes, also an extra 10' pool waiting for them. i would also like to follow in your footsteps with the giant diy tank, already have the glass, but for now i have my bases covered.