Some deeper bodied tetras would work well with theose already suggested too IMHO.
I'd try and get them fairly young, but not tiny. Maybe about 1.5 - 2" long? I'd say say mine were young adults when I got them and a little bigger than that. I only got 4 though and then had real aggression problems when two paired - they killed one and I had to remove the other as soon as possible. I think if I'd had 6 or more it would have spread the aggression around a bit more and I would have had less problems.Thanks Ed. Yes I would love to get the wild ones if I can acquire them. Do you recommend getting them as young as possible?
You might have to rehome some when they pair or the extra numbers may help spread the aggression allowing all 6 to stay together. I certainly know 3 or 4 was a diaster as the pair were able to concentrate their aggression on only one or two others. By the way the pair that formed have got on brilliantly ever since - unfortunately they still haven't spawned yet but I'm working on it! (Or I'm working at getting them working on it! ). If you do have to remove any remove all four spares and leave the pair in the tank where they may spawn and will get on well IME.Ed thanks again for that detailed information. That gives some good information. So it sounds lke if I place 6 or so in the tank from the getgo some might have to come out based on behavior.