Father arowanas exhibit some of the most extensive paternal care among fish. Aside from building nests for their young and protecting them after they hatch, arowanas are also notable for being mouthbrooders.
Some arowana fathers harbor hundreds of baby fish in their mouths, letting them out on occasion to explore. However, the dad always takes special care to seek each one out and suck them back into his mouth to keep them safe from predators. (Check out this video showcasing a protective mouthbrooding arowana).