Black Ghost Knifefish Seizure

[Mykah]

I just did a 10% water change on my aquarium and cleaned out all the plant debris out of my filter. About 15 minutes later my Black Ghost was laying in the bottom where he doesn't usually sleep. I noticed something was off when my catfish swam over him and he got covered in sand but didn't respond. Only the very tip of his bottom fin was twitching. I reached in and picked him up. He was vibrating but not breathing. I checked his mouth to see if something got stuck. But nothing. Was this a seizure? It's truly sad to see him go. I'd just like to have some idea what happened.

I have a attached a gif the BKG before I grabbed it.

The only thing that was different about this water change is that I added a small amount of Melafix because my blue gourami has a scrape on his eye which made it cloudy.

It's a 75 gallon aquarium.
FYI - all my tank parameters are fine. I check them once a week. I'm not gonna list them here because I already know that wasn't the issue.

 

[charliebankston]

Just at a wild guess, I'd say it was prob bacterial. There are a ton of diseases they get, and ime that's the number 1 killer. It's also hard to diagnose and often doesn't show symptoms until too late. My guess is that it was just an oddly timed coincidence that he died right after the water change. I'm sorry for that happening tho, it stinks