I have 20 gallon long that I'll be using for when they're babies but when it gets bigger, I have a 67 gallon tall tank that i was wondering if i should use or sell it and buy a 40 gallon long off of craigslist. The 67 gallon is 36" long, 15" wide and 29" tall. The 40 gallon is 36" long, 18" wide and 16" tall. I'd like to make a background that they can climb up and hang out on with little caves to hide in, and the 67 gal. would do great, but i feel like they wouldnt have enough ground space. What do you guys think i should do?