It sounds like a joke, but I wasn't laughing when it happened to one of my new and very expensive Zebras one week after purchase.
I'd kept the two fish in an isolation breeding tank for the first week and when I came to move them to their main tank I noticed the smaller fish wasn't swimming ...
Another noob caught by the Black and White stripes. Been keeping freshwater tropicals for over 20 years on and off, mainly south american cichlids. Just blown some back pay on my first "pair" of Zebras which will be living with my Discus until I can get their own tank set-up.