Red Tail Shark and cories

If the tank is big enough to allow the shark to have a suitable territory, usually a cave, then yes. It will chase the cories away from it's turf, but shouldn't do much more. Fish that look similar to the shark in form--other sharks, SAE and CAE, for example, will not be tolerated and the abuse will be much worse.
 
I have a RTS with Cories in a 55 and as OG says, they are fine together. I've never had a problem between the 2 species. It seems as though the RTS has picked his own cave while the cories are busy with the other crevices. I've never seen any kind of aggression.
 
My brother had a shark with 2 cories in a 10 gallon for awhile. The shark has recently moved on to a 30 gallon tank, but for the few months he was living in the 10 everyone got along fine.
 
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