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Differences Between Koi and Goldfish
As you wade in the wonder and amazement of how the Koi (Cyprinus carpio)came to be a fish of its status, you cannot help but take another look at its close relative, the gold fish (Carassius auratus). For years, the latter has been very popular among fish lovers. It is, by far, the most popular of pond fishes. So popular, in fact, that the gold fish has been a household name since time immemorial. These two types of fish have been derived from the common carp. Even so, the resulting specimens from the selective breeding process are two very different fishes. Variations are seen immediately in their specific anatomical structures.
Anatomy
The carp belongs to Phylum Chordata or Chordates (vertebrates with notochords), Class Actinopterygii. The Koi and the gold fish both share the same anatomical structures but some of their parts differ. Particular ones have been modified through the years through selective breeding. These modifications help them function well in their environments and make them more marketable ornamental fishes.
Body Shape
Aside from the obvious fact that the Koi can grow much larger than the gold fish, its body shape is also very different from that of its close relative. Because they are basically bred from the common carp, the Koi and the goldfish are very difficult to distinguish from each other when the former is still immature. But once it reaches maturity, the Koi has what is called a fusiform type of body that tapers both at the anterior and posterior ends of the fish. The gold fish is evidently rounder in body shape, making them look more like small balls with fins. This makes them suitable for any environment, indoors or outdoors.
Mouth
Both the Koi and the gold fish have their mouths placed at the anterior part of their heads. The use of their mouths is to, of course, take in water and food. The difference is that the Koi, being bottom-feeders, have theirs just slightly protruding downwards. They usually suck up their food from the sediments at the bottom but still can feed at any level of the water. Another very distinguishable characteristic of the Koi’s mouth is that their mouths have barbels that are used to sense food. The gold fish have slightly upward mouths because they usually feed from the top and middle portion of the water.
Scales and Growths
Gold fish have chromatophores on their skin. These produce these pigments but they have to be exposed to light. It is like melanin that makes us people turn a bit darker when we get exposed to sunlight. When gold fish are placed in dark rooms, they are most likely to turn a bit lighter in color the next day. Some types like the Pearlscale gold fish, have scales that reflect light like that of a pearl, hence, the name. Some of them also have modifications on their heads and bodies. Pompoms have protrusions on each side of the head between each nostril. The Ryukin has a sort of bulge at its shoulder. The Oganda has a wen (hood like a raspberry) that surrounds the head. The Red Brocade ( Shubunkin) has calico scales called nacreous scales. On the other hand, the Koi have a cycloid type set of scales. Some species lack scales (leather carp). Some have heavy, random scales (armored carp). Some have scales that are strategically placed at the dorsal line only (German carp). When you see dark portions of color on your Koi’s body, the scales in that area are overlapping and heavy.
The Koi and the gold fish may have several distinct features but they do have certain similarities, given that they are bred from the same type of carp. These most popular pond fishes aren’t just acquired to beautify your ponds or aquariums. These lovely fishes can be trained as well. The satisfying feeling that you can get from having the Koi or the gold fish can also come from the fact that they can be trained. Gold fish have good memory that lasts three to four months. They can associate light, color, sounds, and their owners with food. They can even make their way through a maze or almost jump halfway out of the water through a small hoop. Koi can also be trained to be fed directly from the palms of your hand. Once you have gained its trust, you can just simply submerge your hands containing the pellets and let it take them in.
However different they may seem, these fishes will always serve as neutralizers for the everyday stresses of life. They will always be considered as great gifts to lighten up your lives. With this, they should be well cared for and be given the respect that they deserve.