Yila also roughly understood that merfolk were actually similar to Demon Dog Trainers, belonging to the summoner's class. Perhaps a large part of their combat power came from their pets.
That would be the "Shield Shell" and the "Swordfish," which sounded like a balanced offensive and defensive fighting style.
As for the fishing, Yila no longer needed to use marking methods to count the number of fish schools. After all, the fishing nets used by the Sea Demons had sufficiently large mesh, and they would actively throw the small fry back into the sea.
It seemed that the Sea Demons also understood the principle of not exhausting the resources through overfishing. Although many other monsters didn't get this, they understood it themselves.
Some things, Yila didn't need to tell them how to do. Before he even spoke, people (monsters) had already figured out the rules of survival on their own, perhaps exploring these truths since ancient times.