How to make an object hold Obi Fluid?

[vivi_j]

I'm working on simulating a Chemistry Lab in Unity. Here's what it looks like right now: https://file.io/6cEnvfVUCXTK. But I'd like to make my object hold Obi Fluid. Here's the mesh: https://imgur.com/a/dz5o3ue. I've tried it with a different object that had more vertices as well, so I'm not sure what's wrong. I suspect that it's an issue with the mesh, but can someone please help? Thanks