Thanks Delsol, the fish is mine. So here is the whole story. I used to have a Mandarin in my old tank, which was by far my favarite. After setting up a 120G BB SPS tank, I really want to put one in the tank. Even though I have more than 100lb of live rock and a 20G fuge with DSB and Cheato, I am not sure if I have enough pods for it. Finally, I decided to take a chance and bought a male Mandarin. I temparory placed it in my nano tank and trained it to eat fish roe, cyclopee, and arctic pods. To my surprise, he was trained very easily. Since he eats a ton, I can not put it in my nano tank for long. So eventually I moved it to my 120G tank, with the six line wrasse as the biggest worry. Sure enough, the six line wrasse picked on it, and half a day later, I do not see the mandarin anymore. After a week of mssing in action, I presumed that the Mandarin was killed

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I was strongly encouraged by the ease of training the first time, so I decide to train a pair, and move the six line out of tank for a month before introducing the pair to the tank. So I bought a large one with short top fin (really fat) and a smaller one with long top fin, assuming they are a male and female. But shortly after putting them in the small tank, the small one starts harassing the large one. That is when I started panicing and want to sell the small one, therefore the craiglist ad. But the surpirsing thing is that they stopped pick on each other the next day. And what's even more surprising is that I saw my first Mandarin in the 120G tank again, healthy and kicking (I guess the poison on his skin taught the six line a lesson).
So if anyone is interested in the two mandarins, I will let the large one go for $12, and the small one go for $8. If you buy both, they are yours for only $18. Not sure if they are trained yet, but the food I put in this morning is half gone. I really want to see these two fish to go to good homes soon because I can not put them in my 120G anymore, and my nano tank is just too small for them.