Too many to remember/list.
Luckily in the decade I’ve been keeping fish, the losses have slowed significantly (in fish I’ve possessed for a while). But accidents happen, and mistakes are definitely still made.
my most recent loss was one of my bichirs, jumped out into an unheated bin (45F water). Also had a spell recently where a couple corydoras got stuck in the tube that directs bubbles from a sponge filter... tube has been removed. Lost a nice little syno cat when I had forgotten to turn the equipment back on after an evening water change (cold), the rest of the fish survived. Yo-yo loach to ich.
I get a lot of my fish secondhand from janky previous owners, horrible conditions, diseases, stressed, stunted, solo fish that need to be in schools/shoals. One tank came with a school of rasbora and black neons, they didn’t handle the breakdown from their old home, and rebuild in my care very well.
my absolute worst luck is neon tetras and pictus catfish.
neons probably 40-50:7
Pictus 8-10:0