One of my loaches is horrifically skinny right now even though he is still eating. It appears to fall into the catagory of "skinny disease" from what I've seen online. I think he has a parasite because all of his behavior is totally normal. Still an active swimmer and eater, even though I can see the outline of his skull and spine. It's very sad and I believe he's too far gone to save (I don't have a QT tank to use currently and don't want to medicate everybody because the rest of the loaches are fat and happy). My question is, is it necessary for me to pull the fish and put him down to keep the others safe, or can I leave him in there and let nature take it's course? I would prefer not to kill my loach, but my sensibilities are less important to me than the health of the other 4.