If you want to catch as many different species as possible, you will have to visit various locations in Fisch. Here's a list of all of them.

How to unlock the Crystal Caverns secret cave door in Prospecting As mentioned, there will be three symbols engraved on the door, and you will need to provide the right minerals that fit the slot.

If you want to collect all badges in Roblox's Grace, here are step-by-step instructions on how to unlock each of them.