I ask because I have a buddy with a 55 he bought off of me that wants a mandarin and he asked me about it. I have a 65 gallon with about 100lbs of rock. I am thinking about adding one myself, but if I did I would prefer to allow atleast a year for pod population to grow to a level that should be acceptable. I hate that so many fish are basically killed in this hobby because they are beautiful and cheap, so people have the attitude that its ok to just keep adding one every few months. I was going to tell my friend that he should get more rock and wait for pod growth, he only has about 40lbs now. Plus he just set the tank up a few weeks ago. I helped him start a fishless cycle that is almost done now, and I recommended that he add a couple of hardy fish once the cycle is complete, until he gets more comfortable with the maintenance on his setup and his tank gets more established.