Nothing important.

[It's not so much that his Stand is a secret so much as that it's a real pain to explain.]

Let's get a better look at you. You're an interesting specimen, aren't you?

[He's talking to the ray, holding it up in front of him and inspecting it.]

Too quick for simple musculature to explain. Some sort of water jets, maybe?

[Yeah, he's just musing about this fish out loud. Or telepathically. You get the idea.]