Okay, my biggest fish has pop--eye. He is a fantail (I think- definitely a flat-body) goldfish. He's about 3 1/2 inches. The eye is filled with blood and is obscuring his vision. Now that I think about it, one of his tankmates had been leaning slightly to one side for a while. Kept a loose eye on it, but it righted itself. No other noted symptoms... but I may have missed some, trying to get a thesis finished on a tight deadline for school.
There are 3 others (2 definitely commons) 1 black moor.
Aquarium is 20 gal.
Filtration is an Aquatech 20-40 whisper quiet (?)
Food is typically a variation of flakes or 2 different types of pellets, with occasional tubifex or frozen shrimp.
Water temp is about 65 F.
I have had this aquarium for about a year now.
Water was foul. Filter covered with algae. Overfeeding? Or possible lack of appetite aquarium-wide. Last 3 days or so, kids had not been feeding too much from what I could tell. Also, water was about time for change. It had been about a month since last one.
I went ahead and assumed bacteria due to water condition.
I did a radical change (50%) vacuuming the gravel, and added aquarium salt at i TBSP per 5 gal. Also added Nitrogen and algae treatments and put a new filter in. I assumed these wouldn't hurt, even if they don't help.
I would like to avoid quarantining him if possible. Last time I did that he was scared of me for a long time. We're just now back on speaking terms... He just broke his avoidance to show me his eye. I know that sounds crazy, but the kids and I could pet him before. Then he got scared and kept retreating to the far side of the tank until today when he came right up to the side so I could see his eye.
Any other suggestions? Also, what are his chances? I know it's probably hard to tell, not being here, but I need something to tell my kids. Finneus is my son's.