red-tailed sharks have red tails, rainbows have red tails and fins. not sure why they are "rainbow" sharks, maybe red finned sharks would be more appropriate.
Yeah, there must be mistake when I purchased them. Maybe I and the guy at the petshop both thought that they were red-tailed black sharks. Hmmm that accounted for the fact that the 'chief' raibow shark doesn't chase others, which I supposed to be raibows!
Thanks!