Buddy! Joshua! A tale of two fish

Last night (Friday) I finally got around to cleaning the fish tank filter system. It had a think layer of crystalized salts all over it and I think this was causing occasional drips of moisture outside of the tank. Besides, it looked terrible. Before giving my big fish to Sandra a month ago, I had not wanted to do this because it required taking the lid off of the tank for 20 minutes and that big fish tended to jump. With him gone, I just had my two long-lived small catfish Buddy and Joshua. I removed the filter/pump, rinsed it with filtered water, scrapped salts off of it and the tank, and replaced everything. Looked good, everyone happy. 

This morning I wanted to see how happy everyone was with a cleaner tank overnight. 

Both fish were dead. 

This is the first time I have had no live fish in over 12 years. I don't know what killed them, but it could not be a coincidence that they both died at once and that I did that cleaning last night. Possibly I introduced something on my hands (a bit of hand sanitizer possibly) but I doubt that this would have been enough. Hand sanitizer was used earlier in the day but I'd washed my hands since then so it could only have been a bit of residue. The heater had been working all the time and the filter was only disconnected for 15 minutes and the fish have survived that long without it before (power outages, etc). Possibly it was the salt crystals. I tried not to have them drop into the tank, but as I removed things, some likely did. They were large and hard enough not to immediately dissolve, but some may have been small enough to eat and they are hard and jagged. Anyway, even though William is not a kid anymore and he is no longer upset but the death of a couple of two-inch long fish, I felt I couldn't just flush them. I wrapped them in a paper towel and buried them in the dirt under some shallow snow in the yard. 

Margaret points out  that we could get rid of the tank now. I'm undecided. .