Regal Tang

Question
QUESTION: i have a well established marine tank which has been doin really well, i have only usually kept my pair of clown fish but just recently i added a regal blue tang. The tang keeps killing all my hermit crabs is this normal? so far she has killed 3 halloween legs plus 2 green hermits, the latest one was the biggest crab in my tank which was the last of my halloween crabs.

Your advice would be much appreciated

thank you

ANSWER: Hi Stacey,
No, this isn't normal behavior. It's a slim possibility though. ALL fish have their own personalities, regardless of the normal species "behaviors"(I have a 3 inch Green Mandarin that RULES his home with a 12 inch Black Spotted Grouper and a 10 Inch Volitans Lion!) How large is the aquarium? How large is the fish we are talking about? And dont take this the wrong way, are you sure of the species? I have known people that were sold Triggerfishand other species, as Tangs, in the past by their LFS. Crab/hermit deaths can frequently be attributed to another crab or worm, a hitchhiker, you havent seen.
Paracanthurus Hepatus, The Regal Tang/Blue Tang, feeds mainly on plankton and seaweeds/macroalgae. It will eat meaty foods, but generally sticks to the forementioned diet of plankton and salad. They are generally very peaceful fish for reefs and communities. The only time Ive known aggressive behavior or territorial behavior is a problem is when multiple, same species are housed together. Have you seen the fish actually do the killing? It may very well be a habit this fish has developed through it's captivity, and if an older fish, quite possibly a habit that was formed out of necessity(most lfs and wholesalers are not known for having good gathering, housing or distribution practices). I would observe very closely to make sure this is the culprit, and if so maybe to see why. You may have to separate the fish from the system. Sorry for the troubles youre having. Let me know if you see anything new or have any more information. I would be glad to help! And this one is new to me so keep me up to date!

---------- FOLLOW-UP ----------

QUESTION: Thanks for replying so quickly. The tang is definately the culprit i have sat and observed it do the killing. she curls herself round the crabs then when she can get a hold of a leg she pulls them out the shells, i did do alot of reading up on the tang before i brought one and they all said they were a peaceful fish so it shocked me to see this happening. As i have a pair of clown fish also it is quite agressive towards the larger one. The tang isnt that big its probably about 1 inch in size and the larger clown fish the same. My tank holds about 150 litres

thank your for your help
very much appreciated

Answer
Hey Stacey,
Wow, thats a new one!
I hate to say it, but this is a habit thats not going to change. It's a young fish so it will actually become more of a problem with age and size. I would return the fish for a new specimen personally. The Regal Tang gets large enough that this behavior will damage/kill most other tank mates you would desire. And you cant change or alter these behaviors, they can be modified with very large systems, but even thats a band aid.(the behavior continues, we just dont see it in a huge tank!)
Take the lil guy back and get one that won't devestate your community. Sorry. Let me know how it goes.