I bought 5 Zebra Danios. I know he made it out of the bag, at least I don't think he jumped out. The wierdest thing is, I only ever saw 4 fish even just after glacing into the tank when I released them from the bag. I don't think that one would still be hiding. I even lifted things up in the tank looking to see if it would swim out. I also rinsed the bag with tank water to make sure it wasn't stuck in the bag. I don't see it floating on the top either. The other 4 area doing great.