Post Water-Change; Fish Immediately Dead?

I completed my weekly water change as I do every week, and as the water was topping off I noticed this fish laying on the substrate nearly dead.
Before the water change, this fish was acting fine and had good color, now it appears to be nearly dead.
Any ideas on what caused this?

[@addictivehobbies493]

That is so weird! I love your vids I just subbed

[@JMARTINEZ7]

Looks like he went into shock.