Long story short:
I bought two comet goldfish awhile back, and absolutely fell in love with them. I transferred them to a new much bigger tank and decided to get a few other different goldfish for a good variety. I chose a calico fantail and a calico telescope. I put the calico fantail and he was doing superb. While on the other hand the calico telescope wasn't. I watched him for many days, and he was sitting at the bottom of the tank, all fins tucked against his body. When feeding time was around, he wouldn't go up to the top of the tank to eat, but eat when it floated closer to him. I believed that the comet and fantail were bullying him. So I transferred him to a smaller tank, and got him ANOTHER tank mate, another calico telescope. But that didn't seem to help. He is still sitting at the bottom of the tank and is extremely lethargic, while the newest calico telescope is doing great. I don't know what to do, could it be possible that there is something wrong with the water? Or did i just get my hands on a bad fish?
I am so sad for the behavior of this poor fish, I don't want him to suffer, what should I do??
Thanks,
Katie

I guess If it were me I would put him in his own tank for now with good airation and add conditioner, salt, melafix and pimafix to his water for 3 days.  From the picture he looks unwell...   He could just have been a unhealthy fish to begin with and the whole shock of a new environment etc.  took its toll on him.

you bought a poor quality fish possibly already on a downward slide, check the photo and compare the size of the head to its body.  The more delicate varieties are best kept separate from the more hardier.