At least in the minds of the BADFISH boat captains it is. It's a long-held superstition that not only bananas, but items flavored like bananas or bearing their image, are bad luck.
If one of these items is found on a boat, as in this video, it is promptly and unceremoniously thrown overboard, usually to the chagrin of the offending passenger.
See how quickly this banana-toting fishermen throws his buddy under the big yellow bus after he's confronted while stuffing his mouth with the fruit.
Lots of expletives follow, but it's clear that the guy felt like he'd passively warned others about his dangerous cargo. No one cares about his excuses and they begin tossing his bananas into the ocean regardless.
There's no word on if the fishing picked up afterwards but one thing is certain: That captain had one less excuse for a bad day of fishing.