Build a niche blog designed around the aquarium hobbyist community. Your target audience could be aquarium enthusiasts, fish keepers, and people looking for information on creating and maintaining underwater ecosystems.
If you have knowledge and experience, you can write care guides, aquascaping, and troubleshoot common aquarium issues. With this focused niche, your blog can be popular among people interested in maintaining aquatic life and home aquariums alike.
Blog Name Idea: AquariumFishCare.com