Clownfish Picking on Yellow Tang :(

[Otters]

I have a pair of clownfish on about 3" big and one 1 1/2" big (false perculas), and a 3-4" yellow tang for almost 4 months together in a 46 gallon tank. The clownfish always stay on the right side of the tank swimming up and down, and the yellow tang gracefully swims throughout the whole tank, theres also one blue chromis. However lately I have swim bite marks on the top of the yellow tang upper fin, BIG ONES, at least 7 bites, I know for a fact the only fish that could do that are the clownfish, and I know they are territorial. Anyways I can ease up the aggressiveness and territorialness the clownfish have developed?

[leebca]

You're sort of faced with the problem people are running into with anemonefishes. Everyone is very taken by them since Hollywood's movie about Nemo and the 'gang.'

Your Perculas are mated or going through the mating process, and are preparing the area for their nest. In the wild a mated pair usually claims an area of about 9 cubic feet for their territory. They assume the tank is their territory since they 'need' the space for the safety of their 'nest.'

It is hard to tell what fishes they will perceive as a threat. Almost any newly introduced fish now is a threat. The old inhabitants pose a threat if the female thinks they do. The female of the pair will be the most troublesome when it comes to territory defense. She will drive fish away and also (sometimes) take out her stress in an aggressive form even on the male.

If it is your anemonefish that is chewing on the tang, there isn't much you can do about it other than remove the tang or the pair. There are 'tricks' to getting fish to get along with each other, but in the case of a pair, these tricks fail and end up adding stress to the fishes.

Sorry for this news.