I inherited a 30 gal
established tank with 2 male dwarf gouramis (blue a little more possessive of his side of the tank than red) almost 5 months ago. A couple of weeks later, I introduced 1 albino corydora. After chasing the newcomer around for a while, things were fine. A few weeks later, I added 3 more albino corydoras. Again, everything O.K
I vacuum, scrub and change 5 gallons of water every 2 weeks. On the 4th week, I also change the 2 filters that hang off the back of the tank (sorry, I don't know kinds -- it was all just thrown at me in one day).
Here's the recent problem: last week, 1 of the "newer" corydoras died. I hadn't seen all 4 together for a day or two and knew I hadn't sucked anyone up the hose when changing the water. Took the blob of fern out of the way the next day and found the dead one on the bottom. The following day I bought a replacement (same kind, same store). Yesterday I noticed the blue gourami is not interested in eating and stays at the top in a corner. Doesn't even both to chase "red" to his side of the tank. Will scurry away as usual when I put my hand on glass in front of him but returns soon after.
Everyone else in tank is acting normally.
I have noticed no spots or color change, no bloating, no tilting to a side, and no gulping.
In reading other forum messages, I am undecided as to whether there is even a problem at all. Old age perhaps? I'm guessing they're about 3 years?
I looked in the box of inherited stuff and pH bottle was empty so I guess I need to get more. I had taken the water to a pet store a couple of months ago and it was just slightly to alkaline side.
I know this is a little vague of the minute details you like, but the suggestions I've received from friends range from hexamite, use paragon, quarantine, too late -- put in freezer............