I have 4 RBP in my tank (48"x24"x18") now, but before I got them I had 1, 3.5" Shovelnose Catfish and 10 Seprates Tetras approx 1' in there. The Tetra population would go down every night by 1. This happened for about a week or so untill I had 6 Teras left and before the pirahnas laid claim to...