I've had the same 4 goldfish for 8 yrs now. They "summer" in a 100-gal pre-formed in-ground pond by our patio. They "winter" in a 50-gal aquarium in the garage....they've been fine with this arrangement for 8 yrs. This winter, the water looked worse with algae (that some water hyacinths helped create, maybe?). A few days ago, I did about a 20% water change and put in new filters into the biological filter chamber (I've even done 25%+ water changes before in the aquarium, and especially in the pond with no problem). I thought the new filters would help better with the algae (I usually put in new ones about once a year anyway).

Anyway, I noticed yesterday that one of the smaller fish (calico fan-tail) didn't seem right. He looks a little better today, but then I noticed that one of the largest ones (regular type?) was "drifting" to his side. Is there anything I can do to try and help them out? I can't "unchange" the water and filters (I rinsed off the new ones before putting them in, but could there have been some kind of residue on them?), and I don't dare do another water change this close to the last (or do I?). I did what I always do....which has been fine for 8 yrs.

I'm in the process of cleaning the outdoor pond of all its leafy gunk (and ice chunks still!), but I like to get it clean and fill it half full with water to let it age at least a few days before moving their aquarium water to the pond to fill it out, etc.....so I'm still days away from getting them into cleaner and "happier" surroundings.

Do I still transfer them to the pond with them seemingly unwell? I like my fish--don't want to hurt them any further. All suggestions are appreciated!

Thank you!

Tracey