Whether you have been in the aquarist’s hobby for many years or have decided to join it only recently, you must have heard of koi fish at some point. Indeed, these spectacularly colored fish present one of the first pet choices for outdoor ponds nowadays, and we completely understand why.

From unique color patterns to fantastic legends which hide behind, koi fish make utterly amazing pets. And there are so many things about them that are not commonly known but are highly compelling.

Therefore, in order to get us to know these creatures better, here comes our list of the most fun and interesting facts about koi fish.   

1. Modern Koi Fish are Bred in Captivity Only

If you see a koi fish in the wild, you may be fairly sure that it was not born there. Actually, these fish have continuously been bred in captivity to achieve such spectacular body colorations and patterns.

So, if you do happen to notice some in the wild, you may be almost sure that they have been released there. In fact, this is a quite common situation during the last years, as they end up in the wild either because of some irresponsible owners who could not find them a suitable home replacement, or even by accident.

Such released fish will start resembling to the original carp in just a few generations. The common carp is, in fact, the species from which koi fish descend.

2. They Grow to a Fairly Large Size

Koi carps are not just beautiful. They are also quite demanding pets, and they grow to a fairly large size. Most species can reach a total body length of 2 feet, while some of them can even exceed 3 feet in body size. How amazing is that?

The maximal size of your koi carps will depend not just on their genetics, but also on their environmental and feeding conditions. Protein-enriched and high-quality meals, a large enough pond and pristine water parameters all make a huge difference.

3. Most Koi fish Outlive their Humans

Oh yes, these fish have a really long-life expectancy. Depending on the particular type of koi carp that you wish to adopt and on the environmental factors which you can provide them with, you can expect your colorful pets on living anywhere between 20 and 60 years. Some of them can live much, much longer, but such cases are quite rarer.

That said, it should come as no surprise knowing that many families (especially Japanese ones) use to keep their precious koi fish for generations and generations. They easily become an important part of the family, but also an important heritage to care for.

4. Koi Fish can Safely Survive Long Winter Days Outdoors

It is of common knowledge that koi fish are mostly kept outdoors, in garden ponds and similar enclosures. This is mostly because of their massive sizes and their consequentially large water volume requirements, but also because they love living in the company of their own species.

However, many inexperienced owners give up on adopting these spectacular creatures because they simply think that they do not have the capability of taking care of carps during wintertime. But that is a common misconception. In fact, koi fish are perfectly capable of spending cold days outdoors with no health consequence.

Once that winter days start approaching, they will start feeding less and less, until they reach a point where commercial food is not needed anymore. Their bodies will adapt to the water temperature, they will become extremely slow and spend the entire season towards the bottom of the pond.

As long as there is a mild water current, a functioning filter, and a hole in the icy surface for air, your fish will be simply fine.

5. Your Koi Pet Cannot Bite You

Large pets can sometimes be intimidating to their human owners, especially if they are first-time keepers. However, there is no reason for concern with koi fish, as they cannot bite you at all.

Their teeth are located deep inside their throat, leaving no chance of bites unless you decide to literally stick your finger deep inside their mouth. Feel free to approach them, and to even handfeed them, as your colorful fish will not hurt you.

6. Koi Fish are Considered as Good Luck Charms

Well, if you have done at least a bit of previous research on koi fish, you certainly are aware of the fact that they are considered as good luck charms across some cultures. But did you know that different types of koi carps are thought to present prosperity in different life sectors?

Golden koi represent wealth, metallic variations bring business success, while black fish hold a patriarchal symbolism.

7. They are highly Intelligent and can Recognize You

If you are looking to adopt intelligent fish which can actually interact with you and your family members, koi fish may be the perfect solution.

These fish can recognize their humans, and they can easily be trained to accept food from their hands. There are a few more relaxing activities than handfeeding your precious pets on a summer day.

8. High-Quality Koi Fish can make a Lot of Money

Oh yes, koi breeders are very well aware of the fact that koi fish are true moneymakers. The industry of amazing koi varieties can earn anywhere from $10 to thousands and thousands of dollars per fish.

9. If no Shade is provided, your Koi can get Sunburns

Even though they are kept outdoors, koi fish are much more resistant to cold conditions than to direct sunlight. Moreover, they can easily get sunburnt if in contact with sun rays, which can obviously cause serious health consequences.

Plants are always excellent natural helpers in providing shade to garden ponds, with floating ones certainly contributing the most.

10. Koi Fish are Excellent Swimmers

Koi fish are one of the most resilient and agile swimmers on the planet. Their ability of swimming in the opposite direction of a strong current, as well as their capability of even moving upstream among waterfalls, is what makes them unique swimmers. And that is exactly why they present strength among some cultures.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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