Okay I've read on here several people suggesting half tires filled with gravel for potential spawning beds, with a mix of larger and smaller gravel, the larger gravel being there to keep from being swept out when the fish fan away the silt with their tails.
My question is this: I've got the top (basin) portion of a birdbath that has a crack in it which renders it unusable. Would that by itself suffice for a bed? My thinking is the fish could fan the silt off easily enough, I'm just wondering if they'd bed on such a smooth surface. Any thoughts?