suitable tankmate for rts

[Big Al]

Hi! I got my red tail shark it's own 15 gal. tank. He was aggressive towards other fish. I was vwondering if i could put some fish in there but i don't know what kind. iwas thinking of 2-3 white clouds. or should she just be in there alone?
Thanks.
Biggy

[firefly]

A 15 gal is kind of small for a rts, so I'd leave him in there alone.(and preferably upgrade tank size. I'd go no less than a 20g long..., and bigger would be better) In a larger space, he could have some tank mates though.

Emily