Some species of fish will actively protect their eggs or young from predators.
Mouthbrooding species
Some species gather up fertilized eggs in their mouth and keep them safe until they hatch, a process called
mouthbrooding.
Cichlid. In addition to being mouthbrooders, some species continue to protect their young after they hatch, calling out to them when there is danger, and letting them swim back into their mouth to hold them safely away.[1]
Osteoglossid are all mouthbrooders. The parents can hold hundreds of eggs in their mouths. Once hatched, the young may make several trips outside the parent's mouth before deciding to leave permanently. Some species also build nests and protect the young after they hatch.