fish killing fish

Question
Dear Karen,
I recently set up a new 10 gallon aquarium tank. So far i've had no trouble with the fish in it. I have had 5 platies, one molly, three tetras, one glowlight, one scissortail, and one african butterfly fish in the tank for several days with no problem. In another tank i had a small irradescent shark and a small bali shark. Yesterday i moved the irradescent shark into the big tank with the other fish becasue my bali was bullying it around. All my fish are supposed to be nonagressive, but since moving my shark i have lost two tetras and my scissortail has a piece missing from his tail. The one tetra had its whole tail eaten off. I personally don't think it was the shark, but then again none of the fish are supposed to be aggressive. Which one do you think it may have been? Just because the attacks recently happened i don't think my shark is to blame. Please help if you can, i don't want to loose anymore fish!!!!!
                              Thank you,
                                    Erin

Answer
Hello Erin!

Well, Erin, although irridescent sharks are known for their peacefulness and docile natures toward other fish. As with almost all fish, most will eat other fish that can fit in their mouth. There IS a possibility that your Iridescent shark was the culprit in the disappearance of your two tetras and the other fish that were injured.
Another concern I have is your African butterfly fish. You see, Butterfly fish are predatory and it is often recommended that you feed them neon tetras or crickets! Your Butterfly fish probably eventually decided he would try one of your tetras as a snack and certainly chased and nipped the other fish.

I'm sorry for all this bad news, but I think it is best if you return the African Butterfly to the petstore or try keeping him in with your bala shark, as long as the Bala isn't really tiny. You must also know that Irridescent sharks will grow 12+ inches in 1-1 1/2 years! Some websites say they grow bigger...like 36 inches, but that is sort of rare and the largest you will get I have known is about 18 inches. Irridescent sharks are beautiful, I love them, I don't know the size of your original tank (not the 10gal) but they should really have at least a 55 gallon tank in my opinion.

I have no conclusion to all this since it is entirely your decision whether or not you wish to keep the Iridescent shark and butterfly fish.

I really hope my knowledge helped, and I am wishing you the very best with your aquarium keeping! I know you, as the concerned fishkeeper, will make the very best decision! :-)

If you need anymore info, or have more questions, just email me again! I am more than happy to help you out all I can! :-)

Once again, sorry for the bad news and much sympathy for your little tetras and scissortail.

Best wishes to you!
Happy fishkeeping!
Karen~