38g would only be good for a single female salvini at most, def not big enough for severum or discus either, salvini are not expensive either and IMO the females are actually prettier than the males in this sp anyways, salvini are quite aggressive and my little female i have in my big tank right now is only about 2in and is already showing amazing color and isnt shy at all, if only you were near me i would actually give her to you as i am going to be posting her sale soon anyways. but yeah if you dont go with the salvini i would suggest a trio of apistos of some sort, you could do the trio with a nice large school of some type of small tetra and youd have a pretty nice little tank without having to worry to much about aggression issues