Does anyone else put mirrored backgrounds on their tanks? I only have schooling fish and non-aggressive species that get along with conspecifics. I like how it adds depth and hopefully the schooling fish feel like they are part of a larger school. When adding new fish I see them swimming right next to their reflection for what I assume is comfort. Since most fish will seek out the safety of a group.
Obviously this is a bad idea with aggressive fish that would fight their own reflection all day long.