How do you keep a hydra as a pet?

So, I'm curious, how does one actually keep a hydra as a pet? I mean, they're known for their regenerative abilities and their multiple heads, so it seems like it would be quite a challenge to care for them properly. Do you need special tanks or enclosures to keep them in? Do they have specific dietary requirements? And what about the risk of them escaping or causing harm to people or other pets in the house? I'm genuinely interested in learning more about how one would go about keeping a hydra as a pet.