Help! Angelfish Dying!

[Akash711]

I believe my 4year old koi angelfish has swimming bladder infection. A few days ago, I noticed that he would just be floating with the current, and when he tried to swim, he'd just go in a circle. Now, he's been laying in the bottom corner of our tank, and his is is getting cloudy, and he can't swim to get food. What should I do? I think he'd eat if I hand fed him, we've had him since he was a few weks old.

 

[fluttermoth]

The first thing to do is an immediate, large water change; and by 'large', I mean 80 or 90%, making sure the new water is temperature matched and dechlorinated.
 
Can you get the water tested at all? Many fish diseases are caused by poor water quality, so we need to rule that out.
 
Don't feed the fish at all for a few days; it won't hurt it to miss a few meals, and the extra pressure of a full stomach wouldn't be good for it, in it's current state.
 
Best of luck; it's awful to lose a fish you've had since a baby