Some mother fish, called mouthbrooders, hide their babies in their mouths (risky yes, a few can and do get swallowed). That might be what's going on here.
@sincere_milkshake, @rosalinas, this fish is either hiding her babies from predators, or they're cleaning parasites from the fish's mouth. They even do this for sharks and sometimes crocs/alligators. They're not being eaten.
They were just minding their business
And stop going like those small fish