There are legends that the human race appeared from creatures resembling amphibians, covered with scales and breathing through gills.The underwater world is hidden from sight by layers of water. That is why water is associated with the subconscious. Knowledge is inaccessible (according to Freud) within the depths, but accessible to the fish!
Jesus Christ made an analogy between fishing and turning people to the new faith. This is where the tradition of baptizing with water came from. Hence, the Pope wears the Ring of the Fisherman. Three fish in a group are a symbol of the Christian holiday - Trinity. Obviously, this triad is announcing the toast for “fertility and reproduction”, and of course, a clean environment.