The best way to experience Roblox Fisch is to do so on a private server. That way, you don't have to deal with random people who will try to annoy or lecture you with unnecessary advice or tips, or ...

About Server-driven simulation framework for Roblox — simulates entities like fireflies and bouncing balls server-side, with lightweight client-side rendering for performance and visual effects.

The Steal A Brainrot Private Server Guide provides you with a lot of free links along with instructions on how to use it properly.