New addition combat

[goog]

After a 6 week quarantine I added a medium sized Naso Tang to my 180g tank. My 180g contains a medium-large Yellow Tang, a small Coral Beauty, a small Blue Tang, a Dog Face Puffer, a Bangai Cardinal, and a small Blue Chromis. It's been my experience that the addition of a new fish throws off the social equillibrium of the tank for a few days and eventually everybody will settle in and stop the minor skirmishing. After 24 hours the Yellow and Naso are still intermittently skirmishing which I don't find alarming but I am concerned about what appears to be a small wound (dark spot) the Yellow inflicted on the Naso. The Yellow appears to be slightly more agressive but the Naso doesn't seem intimidated. The Yellow was the last addition to the tank prior to the Naso about 15 weeks ago. I have heard of Tangs fighting to the death, when should I intervene and pull out the Naso. The QT is still up and running.

TIA!

[leebca]

You may have been mis-informed about the nature of a Yellow Tang. Once established most of these will not tolerate another Tang coming into the aquarium. If you really want a Yellow Tang, add it last and make it the smallest Tang in the tank.

For now, find another home for the Yellow Tang or the Naso. All the other 'tricks' of rearranging decorations, taking the fish out and putting it in later, etc. rarely work -- the YT thinks the whole aquarium belongs to it and once it settles in again, with take offense to the Naso.

You are also faced with, over a long time, the YT will become belligerent with other fishes, starting with the other Tang you have. It's just their nature. Now and then one comes through with a more tolerant attitude and those are worth keeping!