After the guppy is mature, the fetal spot will appear on the body. These fetal spots do not grow on the surface of the fish, but exist in the fish. The fetal spot is actually the egg of the female fish, so it only appears on the female fish, not on the male fish. Moreover, the male fish's body is opaque and can not see the substances in the fish's body. Because the body of the fish is transparent and the color of the fetal spot is dark, the fetal spot can be seen. When there is no fertilization, the eggs are in the abdomen of the fish near the anus. The black patch in the anus is the fetal spot.
1. Color distinction: The black spot of guppy is black, and its color won't appear commonly apparent change. The color of the fetal spot is not fixed. In different species of guppies, its color is different. But most of the spots are black, and only the white guppies have orange spots.
2. Location difference: Black spots will appear in various parts of the fish body, relatively scattered, generally not concentrated in a certain part of the long. And both males and females may have black spots. But the fetal spot can only appear on the female fish. Because the fetal spot is the color of the egg, it can only appear near the anus of female fish.
3. Size difference: generally speaking, the shape of the black spot is relatively small, and will be scattered, there will not be a number of gathered together to form a large black spot. The fetal spot is formed because of the color of the egg. The number of eggs is relatively large, and they are all in the anus of fish, so the area of fetal spots is relatively large.
