Why would my Zebra Danios disappear?
Zebra Danios are tropical and goldfish aren’t. I would imagine the minnows would have been eaten first. If you stress danio, they play dead, they could be on the gravel and if you don’t actually give them a nudge they don’t move. That would happen if they have been chased. Most plecs are omnivores and a danio playing dead could just be mistaken as carrion.