parasites?

[Invigor]

Well, I going to give mardel's maracyn-2 a try, because of the absorbtion through the skin property of Minocycline, I think it's got a good chance of killing any possible internal infection.

And for the rest of it, I'll do a 50% waterchange, and try to inject fresh outside air into my tank. Apparently high concentrations of dissolved gasses (o2 and n2) can be a cause of popeye as well. This could be possible as my tank is in my poorly ventilated basement area.

[i have crabs]

i had a damsil with popeye and i just kept soaking his food in garlic and vitamins (i think either zoe or selcon) and it got better quickly

[Ruth]

I think you might be onto something with the air quality. You can try to run your air intake for your skimmer outside as this is supposed to be a really good way to get the air into your tank water. You might also try opening a window (if possible) and putting a fan in it to bring in more fresh air from outside.

[Rondelet]

Popeye is caused by a lot of things but it's most commonly due to a bacterial infection, physical trauma, ammonia toxicity, or gas saturation in the water. I doubt poor ventilation would lead to gas saturation. Check your water pumps to see if any of them are sucking air in - as this could led to saturation of gas. Even so, it would be fairly rare in a home aquarium. You need to get your water quality sorted out - best done through lots of water changes. You may also consider giving your fish an antibiotic treatment via the feed if possible. I would advise against added antibiotics directly to your water for a variety of reasons, but mostly because 1) efficacy is poor; and 2) they will upset your biological filtration; something that would exacerbate your situation if your nitrogen cycle gets thrown off and ammonia starts to build up. I would try administering an antibiotic via the feed, which is a more efficacious route of administration. Any of the Seachem (Focus + any of Sulfathiazole/Kanaplex/Neoplex) or Aquarium Products (eg Gel-Tek Ulta Cure BX) would be good choices to consider.