Intro: 80 gallon tank, 1 common goldfish (6"), 1 commett (8"), 1 pleco.

1. The other day my goldfish developed a bubble around one of it's eyes, its eye wasn't clouded over, but I assumed it was popeye. I had cleaned my tank a week earlier and the filter 3 days after that and did something that drastically threw the nitrate and nitrite levels off. I did a 1/4 water change and added something to level the nitrate and nitrite levels, and something to boost my biological filtration creatures. Almost immediately the bubble around the eye shrunk, two days later it is almost completey gone and i'm sure in another day it will be totally gone, but the fish has a little patch of fungus on it's lip. Should I treat the fish anyways?

2. This may be a bizzare question, but do fish fart? Occasionally I see both the commet and the goldfish release bubbles where poo should be, is this normal? :P

It doesn't quite sound like popeye which is fluid behind the eye making it stick out. It sounds like some sort of bubble more like something a bubble-eyed goldfish has? Something like that may appear for no reason or perhaps from something being off in the gas levels in the water. It may deflate on its own as you saw. If there is fungus (fuzzy and white) on the lip, then treat with aquarium salt (a tablespoon per 3 gallons so as not to pester the pleco) and a fungicide (like MarOxy by Mardel). Note that plecos will suck on and hurt goldfish. Is it possible this was a physical injury caused by the pleco? Keep an eye on them.

Fish, like all animals, have bacteria in their intestines which produce gases. If things are more out of wack, then more gas gets made. It's not uncommon for fish poo to have gas pockets in it. I've not seen gas come from a fish's vent and float up but have seen it in the waste line, enclosed inside. Goldfish often get this from a poor diet or stress (like your recent water quality problems). Try feeding some veggies like boiled and peeled peas. When I had indoor goldfish, and they got sick, the abnormal poo with gases in it was often a sign that something was wrong.

Robyn, I can always count on your site for helpfull info.

The pleco seems to keep to itself, even at night when it usually comes out. The fungus showed up about the same time as the bubble so I'm sure it was the nasty water conditions, the gas bubbles have stopped too. I think I'll watch it another day and then add salt, but both the fungus and the bubble are just about gone.

Thanks,
Mandy