no, that's not fictitious, that's been there for years. It's an entire "health club", so to speak, and is on rue Pontoise in-between the Seine and place Maubert. It's called Club Quartier Latin They used to have their own website I think this is it

http://www.clubquartierlatin.com/

Great 50 metre pool at Chatelet. Pay when you get there -- almost always has lap swimming. Enjoy!

When my son was about 10 we had a great time at AquaBoulevard, near the Eiffel Tower i think. Yes water park with slides, etc. but also lots of swimming space. Great place for kids. and there is a bar so parents can imbibe why watching the kids splash about.