Thank God I took Biology seriously in high school
Education not only gets you a degree that helps you get a job but also helps you understand interactions and jokes like this. The carp is a fish species known to be the prey of most seabirds, and this picture shows a typical prey-predator relationship in the animal kingdom.
The caption means the opposite as it states the carp is flying, and the bird sits on the carp like a conveyor. The joke went over many people’s heads as they kept on trying to discern the true meaning. Thankfully, some people stood their ground by reinforcing the post, all to the dismay and confusion of others. This is why the internet is the best.