tropical sharks -

Question
I have a 48 gallon tank with one angel fish, one algae eater, and one red-tailed shark.  I just acquired two sand dollar fish 4 days ago, and I have now noticed the red-tailed shark chasing the two sand dollars.  Now what?  I have tried moving things in the tank - and I have now taken the shark out of the tank.  Should I put him back in the tank after an hour of being out?   I am ready to send it back to the fish store.  

Answer
Do you mean "silver dollar"?  Sand Dollars are marine.

Red-tailed sharks are funny that way.  Mine chased everyone in the tank until he was the smallest fish, then he was fine.  There is a chance that he will stop chasing your fish when they get bigger, but there is a better chance that he will always be a bully.  If you are unprepared to deal with the aggression and want a peaceful tank, I would trade him in.