Well, it could be about empathy. The boy might put himself in the fish's shoes, so to speak. If the fish is in a difficult situation, like being trapped or lost, and the boy helps it, it's teaching us to feel what others are feeling. We should care about the well - being of others, whether they are humans or animals. This kind of empathy can make the world a better place as we would be more likely to help those in need.
In the 'boy and the fish story', the moral might be related to respect for nature. The boy's interaction with the fish could teach us to respect all living things. If he treats the fish well, it shows that we should not harm or take nature for granted. For example, if the boy helps the fish when it's in trouble, it implies that we should also be there to protect nature when it needs us.
The moral could be about kindness. Maybe the boy shows kindness to the fish and is rewarded in some way, like making a new friend or learning an important life lesson.