Minecraft dolphins won’t do anything?

This might sound like a silly question, but I’m trying to make an aquarium that’s underground. I made an enclosure for the dolphins (a small area surrounded by glass for viewing, and around that is a fairly large area of mainly water, which is where the dolphins are supposed to be), but every time I try to spawn them in they float to the top of the water and just sit there (I have a space of air at the top so they won’t drown). I tried spawning in a bunch of dolphins after the first few wouldn’t do anything because I figured since they’re supposed to be social they might like more being around, but they all just float to the top without swimming around or anything. Am I doing something wrong, or is this normal behavior?

I’m playing on the xbox 360 version, latest update.

Edit: Sorry I’m late, but I am still in creative mode. It’s hard to properly describe the underground tank, but to paint a picture, it’s a fairly large, circular area, with lapis lazuli/stone walls. It’s dome shaped, and at the middle/bottom is a glass dome for viewing. There’s 2 blocks of air above the water, and I think the water is all source blocks? There isn’t a running current, if that helps. Again, sorry, and thank you for pointing that out.

Solution 1:

This could either be from not having a direct line of sight to the sun, much like a beacon, or it could be because they are not in an ocean biome. Try these, if neither work I could try some other ideas.