Ok, I am going to get flamed for this!
is a 55 gallon two small for a Yellow? The simple answer is YES, however, I bought my Yellow Tang knowing my 55 was two small for it. I just couldn't take it anymore as I passed by the poor guy in the pet store for three months before I said I will take it.
He was in a bigger tank with a bunch of aggressive tank mates that nipped him and tormented him. The poor guy was not healthy looking and his fins were all but gone. He looked like he was on life support when they moved him to a small 20 gallon tank with his tank mate a Yellow Eye Tang. Both fish were too small for the tank in the pet store, but pet stores do not care. No one would buy the pair! No one wanted a Yellow tang that was not healing and looked like he was destroyed and on his last legs.
I came to this website and asked if the fish fins could grow back, and when I got the answer of "Yes", that's when I decided I was going to try and rescue the guy. For three months I passed him up, because of how awful he looked. I went to the pet store and bought both him and his tank mate. Knowing that I was taking on a big responsibility.
I dripped acclimated them both to my tank, and a few months later my Yellow Tang turned into the premier fish in my tank. All of his fins are grown back and he is fat and healthy now. He has also grown!
I am now working on a 120 LONG tank (Which I am just one barrel away from setting up, Making my water takes forever with the RO
unit I have.
), he and his buddy will be housed in a tank that will best suit their needs for their whole life.
Why am I telling my Tangs story? The answer is because if you KNOW you are going to get a bigger tank in a few months (like I did), and the poor guy is in a small tank at the store, than I would get him out of the small tank and into your tank to house him for the time being.
IF YOU ARE NOT Planning and upgrade, or you are more than a year out. I would stay away and let it go a better home (hopefully). I have seen WAY worse conditions for yellow tangs that would make your head spin at peoples homes. So a 55 would not be bad for a small tang that is growing if you can get him into a 100 gallon tank minimal within 6 months (A really small one). I bought my Yellow Tang all torn up, I knew the risk, but I am glad I bought him because now he is happy and healthy. A fish that is stressed will not heal properly, if my tank was too small I would argue that he would not be the fish he is today if I had not bought him about 9 months ago.