it has to be something polluted your tank. Even I leave far east for work for 3+ months and my dad feeds my fish and my friend did 1-2 water changes on my tank for me while I was gone and all my fish survived.
That really sucks! Sorry for your loss ):
just looked at my catfish again and the main tank. main tank is 100% perfict no problems. my catfish seem like their wiskers are rotting off and their skin is peeling off their bones. i don't know what the hell is going on. they are in a different tank and they are worsening. they are the only fish in that tank. the other tank they were in (the 180gal) is showing no signs of anything. the gar are 100% normal with out any issues. what ever this was it wasn't just vomit and it is fast acting and only affected the aros and catfish.