The ichthus is a symbol consisting of two intersecting arcs, the ends of the right side extending beyond the meeting point so as to resemble the profile of a fish. It was used by early Christians as a secret Christian symbol and now known colloquially as the "sign of the fish" or the "Jesus fish".The ichthus is a symbol consisting of two intersecting arcs, the ends of the right side extending beyond the meeting point so as to resemble the profile of a fish. It was used by early Christians as a secret Christian symbol and now known colloquially as the "sign of the fish" or the "Jesus fish".