This just has to be a Onion story.
Your thought is kind of correct. RTL is a Belgian TV network that, from what I've tried to read on the French-language Internet, does a "Fish of April" fake news story every April Fools' Day. This was probably RTL's "Fish of April" this year. Many folks on
French -
language forums have pointed this out. So far, as far as I know, the story had only been picked up in the English-language wires by an obscure Russian news agency. You'd think it would have been all over the AFP wire if it were true.
The original RTL video (in French) that aired on April Fools' Day is available
here. I don't speak French, so I have no clue whether they pointed out the story was fake. But it looks over-the-top and fake to me.
I would appreciate it if a French-speaking FReeper could tell us what the story said and if RTL mentioned the story was a "poisson d'avril".