What can I do for my (possibly posioned) betta fish?

Yesterday I changed the water in my betta fish’s bowl. I did it exactly the same as I always do it (room temperature tap water, treated with tap water conditioner), but a couple hours after I put him back into the bowl I noticed that he was kind of floating aimlessly instead of swimming. Usually I don’t have any problems, but this happened to me once before (that fish died), and I guess something was wrong with the water chemically.

I took him out of the bowl and put him in a smaller container filled with bottled water, which doesn’t have any of the harmful chemicals in it like tap water does. He’s still alive and breathing, but he’s not swimming or even floating. He’s just lying on the bottom of the little bowl, and every once in a while he’ll try to get up and swim, but he just sort of keels over.

So what I want to know is if he might recover, or if this is a permanent condition. If it’s permanent, and he’ll never be able to swim again (even up to the top of the water to eat), what are my options in regards to fish euthanasia? Is there a way I could give him a quick, painless death? I’m going to wait a few days to see if he improves at all (honestly, I didn’t expect him to live through the night), but if not, I don’t want him to end up starving to death.

I don’t have any helpful advice, but I am curious if your fish recovered. I hope he did! Good luck!

He’s still pretty listless, although he was floating a little on his own earlier. I made a little sling to hold him upright.

Upon doing a search, I am surprised by the recommendations I found. Doing a 100% water change in a larger tropical tank like mine is an absolute no-no, but is okay for bettas. Here are some links I hope you find helpful, or perhaps can lead you somewhere that is.

betta diseases

betta medication

Good luck, bettas are beauiful.

I don’t have any useful advice, but I hope your fish gets betta soon. :smiley:
I hope that made you smile, and not want to beat me over the head with a large fishtank…