I am going to be acquiring a 125-180 tomorrow, and I'm planning on setting up a community tank with 5 geophagus surinamensis. I don't really want to use a sand substrate(but if it comes down to it I will). I was wondering if a smooth pebble substrate(something like this: http://www.internationalstone.com/images/ap.jpg) would work well for them, or if there's anything similar I can use. Thank you.