fish popeye (missing eye)

Question
so i have a krib that lives with loads of other fish in a 55 gallon tank. i noticed about 4-5 weeks ago it had a slight case of popeye and i was treating it, but it seemed to be getting worse. I've now noticed that its eye has either fallen out or another fish pulled it out. i need to know if i need to put any medication in the water or if it will even survive.

it cant seem to swim well and is just sitting on the bottom of the tank. the other fish are not bothereing it at the minute.

http://www.flickr.com/photos/50593241@N02/6243396586/

not sure if the link will work, but thats what it looks like now

Answer
Sarah,
The best way to treat him is to remove him from the main tank and put him i your hospital tank, that has been running and cycled. Add some aquarium salt to his water. The ratio is 1 teaspoon per 1 gallon of water. Make sure the salt is dissolved before you add it to his water or you can burn him. I believe this was an injury that cause the problem. Once he is better you can put him back in the main tank. We move our fish to hospital tanks so that when there is a problem, we treat only the fish that need it.