Adonis are slow growing, expect 1-2" every 6 months. They actually attain a size of 24" in aquaria. a 125 will not be big enough for life. The spots will fade with age, sometimes completely. You CAN keep multiple adonis in the same tank, you just have to offer enough hiding places for all, just as with any other pleco species. Be wary of other species of pleco that become very aggressive, there can be extensive fighting, but very rarely does it end in death. Males and females can be deferentiated by odontode growth, if you are use to seeing the differences, as well as by the papilla. Good luck, they are a beautiful pleco, and fun to keep.