Okay, I was at my LFS and over-heard someone wanting to buy an Ornate Bichir. He told the salesman that he would put it in his 55 gallon tank that has river rocks for substrate. I'm glad that the salesman wouldn't sell him the bichir because he told the guy that river rocks are hard to vacuum clean and food and waste gets trapped very easily. Also, the bicher would have a hard time feeding if the food gets trapped in the rocks. I believe that's true also. Anyone else want to give their opinion or experiences with bichirs and large rocks?