I quite sure my 24" silver is in deep trouble. He's been swimming around with his tail out of the water for over 2 weeks. I'm noticing a 1.5" long "rotting" area on the part of his back that's out of the water. Not surprisingly, he is not eating at all or just a small piece of krill or scallop once a day. His 2 polypterus tankmates are doing just fine. The aro is about 5 years old. This guy just can't seem to float horizontally. His tail always comes up and out of the water. If any one has some advice, I'd love to hear it... this guy is family