None unless you plan on rehoming them in about a year or two. They will grow pretty fast and get to about 8" you should really have a bigger tank for them. You could uncomfortably fit one, but you should really consider something smaller if this is a long term placement. These fish also like schools so getting one isn't the best idea either. Maybe just get some dwarf loaches if you are set on loaches, they only get about 3" and should be kept in groups of at least 3.