Zebra danios - infection?? or old age??

[Pinky]

I have 3 danios in a 15g tank - they are about 2.5 yrs old - 4 days ago one had a mark on g=her back that looked almost like a scrape - kind of a ratty appearance and pinkish red - it did not get any worse or better......yesterday she appeared to be sluggish in the morning....a half an hour later her eye was all popped out and red......3 hours later she was floating with no eyes and her body looked like it had a cobweb like appearance. A similar thing (no eye issue) happened with cory cat - the LPS told me when they get old that this will happen.....Is this correct? I my past years I never recalled this happening. The other danios are fine right now...but now I am concerned.

[annageckos]

It sounds like maybe an infection or fungus. How often do you do water changes and how much water do you take out? What are your parametes?(Ammonia, nitrite and nitrate?)

[Algenco]

yep, sounds as though the fish was injured somehow and infection/fungus set in, don't believe it had anything to do with age