Angle died

[Nysignguy]

Hey everyone new to the site. I have a 72 bf fish only tank. I did a 20% water change and then all a sudden my blk fin angle died with in 2hrs of doing the change I tested all the water it's all good. Not sure what it could be? All the other fish look fine. I also have what looks like a yellow tint in the water what could that be. Should I do another water change ?
I'll post pics if I can figure out how from my iPhone.
Thanks

 

[dollabill420]

There should be a little attachment bar that says "attachments" right above where you start typing when you reply, there is on my iPod on the free app anyways, sorry for ur loss it must be devastating