Can you make a biome similar to "Ocean"?

Hello, I have been searching if in MCreator you can make a biome similar to "Ocean", and I have not found a way to do it. I want to do this because I want to create an aquatic creature, but if I do that spawn in the ocean biome, I have in mind that it will appear both in the overworld and in my dimension. If there is a way to make this not happen, I would appreciate it if you told me how to do it.

Thanks.