Howdy, folks. It's been a long time since I last posted... my setup has been going for almost three full years with very few problems. (I suppose I'm well overdue for photos...) I have a 55 gallon freshwater planted tank with primarily rainbow fish. My stock includes: 1. 4 Turquoise Rainbows (2 male, 2 female) 2. 4 Boesemani Rainbows (All male; two were "oops-es") 3. 2 Madagascar Rainbows (Paired) 4. 2 New Guinea Reds (Paired) 5. 2 Kribensis (Paired) 6. An Otocinclus 7. A Nerite Snail Once upon a time, I had a golden angelfish in that setup as well. Sadly, goldie died on me recently after two years. I decided to replace her with a Roseline shark at the recommendation of my LFS. His gorgeous rainbow tank included two. Well, the first one I attempted to put in to my tank was virtually DOA. After floating, adding my tank water in to the bag and then emptying the bag in to a fish net, discarding the bag water and introducing the fish to my tank, the roseline shark immediately went belly-up. I mean... seconds. I went back to the LFS who asked for a water sample. As expected within a three-year old tank, I had no ammonia or nitrites and nitrates were simply off the chart. (They have been for years... it's an overstocked, planted tank) He chalked it up to just a bad fish and replaced it with another one. I brought him home and attempted to be more careful about the introduction procedure... I added the water from my tank to the bag more slowly, over the course of hours, not minutes. The fish stayed in the bag for about 4 hours as I did this and looked plenty healthy. I then added him to the tank in the same fashion, catching the fish in the net and discarding bag water, and then added him in to my tank inside of my breeder tank to make sure that the other fish wouldn't get close and attempt to pick on him. Well, this guy lasted for a few hours, but is currently belly-up on the bottom of my breeder tank. He's still "breathing" and occasionally will jump up and swim around upright for a few seconds, but always ends up on his back at the bottom of the breeder. Like I said, the other fish can't even get to him. Any immediate thoughts on what might be going on? I don't feel like there is any disease or trauma here... If there was disease, I would have seen it in the fish in the bag, but they go belly-up upon introduction. I suppose I could have put him in to shock or injured him when moving from the bag in to the breeder, but I try to always be as gentle as possible and don't think I did anything that would have caused harm. What am I missing?