It's likely you're thinking of a few things:
* Mudskippers: These fascinating fish are amphibious and spend a lot of time out of water. They can even "walk" on land using their pectoral fins. They live in mudflats and mangrove swamps, which can have puddles.
* Small fish: Some very small fish species can survive in temporary puddles, especially after rainfall. These puddles are usually connected to larger water bodies, allowing the fish to migrate.
* Fish larvae: Some fish lay eggs in puddles, and the larvae can live there for a short period before migrating to larger water bodies.
Let me know if you have more details about what you were thinking of, and I might be able to give you a more specific answer!