Koi fish is a cultured ornamental fish. They come in various colors, such as red, white and black. Red carp is a mutant of wild carp. They only have one kind of red. Red carp is a native species in koi fish, and it is also possible for koi fish to cross to produce pure red offspring during the breeding process. But most of these pure red fish will be eliminated because their overall ornamental value is not as good as that of multicolored fish. First, the difference between koi fish and red carp Although both koi fish and red carp belong to Cyprinidae, koi fish is farmed artificially, and there are many colors, including red, white and black. Red koi fish is a variation of wild carp, which will lead to red body color, so red carp has only one color. However, red carp is the original species in koi fish. Even now, koi fish occasionally appears red in the breeding process, but this kind of carp is generally eliminated, because pure red carp is not as good as multicolored carp.

Second, the difference between koi fish and goldfish is 1. Different species: Although goldfish and koi fish are similar, they are both bred by acquired variation. But koi fish is a variety of carp, and goldfish is a variety of crucian carp, and their categories are different.

2, the appearance is different: the first is the tail, koi fish is usually single-tailed, and some are double-tailed. But most goldfish are double-tailed, and some mutant goldfish are even three-tailed or four-tailed. Followed by body length, koi fish's body length can reach 50 cm, while goldfish are generally around 20 cm, and some species, such as grass goldfish, can only grow to 30-40 cm at most. Finally, the beard. Goldfish has no beard and its mouth is up. Koi fish has beards on both sides of his mouth, with his mouth facing down.