First thank you for having this place, it has been on of my go to's for research. Recently at my LFS I was getting some madagascar rainbows and in the same tank was a fish I didnt recognize. Long story short they didnt either, it came with the madagascars and I got an ok price on it. Attached is some pictures, it is about 2.5 - 3" long, golden green on top shading to a silver belly. The fins are what is different, the tail of the body is a black triangle where it meets the rear fin, from there it turns to white then translucent with two hints of red mix inbetween the black and white. The top fin is white at the base to translucent as it goes up. It seems completely peaceful, hangs in one spot of the tank for days now though every few minutes it runs a short or long lap around the tank before returning to the same spot. It will sometimes school with my various rainbows but not for long. It does not eat algae or off the bottom, it will eat flake but often spits the pieces out as fast as they go in. I have had him about 3 days now and he doesnt seem to be losing any weight even though I dont see him eat much. We think he is a form of tetra but my searching does not give me any hints as to what kind and he is much larger than any tetra I am personally familiar with.