Ok,
This is the second one I've seen this week. Has to be a pool specific thing, because I've seen them no where else, and I've dealt with every conceivable flex tube fitting you can imagine. Except these, I guess.
I would look for them where pool builders get supplies. In the meantime, a clamp might work and it's worth a try if the leak is around the ferrule of the fitting, give it a shot.