User blog comment:SvarkImad/Merman and Devil Fruit/@comment-457332-20120824051140

Mermaid/Merman could eat a Devil Fruit (which begs the reason why) but, lose the ability to swim the only possible way to swim again would be to wear Bubble Coral. They wouldn't blow up. This is proven with Vander Decken who is a simialar spieces the Fishman.and the exact situations apply to him.