* Seals are mammals. They breathe air, give birth to live young, and nurse their babies.
* Birds are also not fish. Birds are warm-blooded, lay eggs, and have feathers.
* Fish are aquatic animals that breathe through gills and have scales.
It's possible that "seal bird" is a misunderstanding or a made-up term. If you're trying to identify a specific animal, please provide more information!