Angelfish are a popular freshwater species and there are three different varieties to choose from for your home aquarium. But once you have made the pressing choice of which type of angelfish to go for, there is then the issue of suitable tank mates. While angelfish are relatively placid and will live happily with a lot of species, there remains the question of whether angelfish can live with koi fish.
Angelfish and koi probably wouldn’t do each other much harm if they were housed together, but that doesn’t mean that they should be. Both of these species require very different habitats and conditions so it would be very difficult to get the water to a point that suited them both.
Angelfish aren’t huge and will happily live in an indoor aquarium. But they require warmer temperatures. On the other hand, koi fish can grow much larger, up to 24 inches, in some cases meaning they need an outdoor pond. Furthermore, they thrive in much cooler temperatures, for which, this outdoor environment is perfect.
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Living Conditions For Koi And Angelfish
Many aquarists attempt to keep angelfish and koi together and for the most part, they won’t bother each other very much. These are both gentle and easygoing species that aren’t out for a fight. The only time that koi are known to become a little more aggressive is when the living conditions aren’t right and the fish become stressed.
For this reason, you will find that the animals won’t fight and will have a relatively harmonious existence. That said, since both species require very different living conditions, this can make it difficult to keep them together.
Angelfish
Angelfish are small in comparison to koi, therefore they do not need as much space and so are frequently kept in an indoor aquarium, along with other, similar fish and invertebrates. In this wild, they are native to parts of South America, particularly in the Amazon region, and tend to prefer calmer, slow-moving waters. They do not like direct sunlight and will typically be found in areas that are well shaded by trees.
For this reason, when keeping angelfish in captivity, it is advised to provide several floating plants to simulate these overhanging trees. You can also place driftwood vertically to replicate the trees in the water, in the wild. You might also like to provide your fish with lots of large-leafed greenery.
While they are much smaller than koi, they are still considered to be one of the larger freshwater aquarium fishes and so require a tank that is at least 55 gallons; you can go bigger if you have the space and financial resources to do so.
Where water is concerned, the angelfish is an easier species as there is a little room for movement on the parameters. That said, we wouldn’t recommend going too overboard and try to keep as much balance as possible for your fish. The pH level of the water should sit somewhere between 6.8 and 7.8 and the water hardness needs to be between 3º and 8º dKH which is equivalent to 54 to 145 ppm.
You will need to make sure that the water temperature is consistent and stays between 78ºf and 84ºf. Furthermore, it is important to ensure that the filtration system you have in place is excellent and well maintained. It is also recommended to perform at least a 10% water change every week or a 25% water change if you are doing it every two weeks.
Koi
Koi are also freshwater fish but the conditions that they do best in are vastly different to those of the angelfish. These large fish can grow up to two feet in length and this is one of the main reasons that the two shouldn’t be kept together. Koi generally do much better in a pond than a tank (we have an in-depth guide on can koi live in a fish tank, so be sure to check that out for more information.
The koi can be kept in an aquarium as juveniles, but this should be a purely temporary measure. Once you are able to rehouse them in a pond, do so as quickly as possible. The pond needs to be at least three feet deep. This is because, during the winter, there is a significant chance that the water will freeze. However, when it is deeper, the fish are able to swim to the bottom and avoid the ice, remaining healthy and safe during the colder months. If the fish freeze with the water, it’s game over! But usually, well-looked after koi can live up to thirty years!
One of the biggest issues for fish keepers with koi is that an imbalance in the water can cause health problems, and in the worst cases, death. For starters, you must ensure that the pond has a top-quality filtration system to ensure that there is not a large build-up of ammonia or nitrite which will kill the fish. While it is OK for the water to have some nitrate, the reading for this should only be between 20 and 60 ppm.
Compared to angelfish, koi need a much higher pH balance within the water and this should be anywhere between 7 and 8.5. Moreover, you want to make sure that your koi are kept in slightly harder water as the minerals within this will prevent too many fluctuations with the pH.
In terms of temperature, koi are very adaptable and will be OK in a variety of temperatures. As we have mentioned, they will simply swim in the warmer depth when things get a little chilly. Some people like to include a floating de-icer during winter to create a gap in the ice that allows for healthy gas exchange, but this isn’t essential.
Much like keeping angelfish, being a koi owner will require regular water changes, although this doesn’t need to be as frequent or as much. You should aim to change 25% of the water each month. However, on a weekly basis, we would advise checking the quality of the water to ensure that any issues can be quickly addressed.
Feeding Times
One of the biggest issues faced by owners who keep angelfish and koi in the same habitat is feeding times can become something of a nightmare. Now again, we must reiterate that both species are placid enough to leave one another alone but that doesn’t mean that the koi won’t do the angelfish harm in other ways.
You see, when it comes to feeding in nature, it’s a dog-eat-dog world and the koi, being the bigger fish, will take over at mealtimes. They are much larger and often quicker and so when you add food into the water, they’ll often be the first to get it. The smaller angelfish are unlikely to put up much of a fight and so, over time, you may find that they do not get enough food to thrive.
What Fish Can Live With My Koi In A Pond?
Since koi are laid-back fish that don’t tend to cause many problems, there are a lot of other species that will happily cohabit with them.
- Goldfish
- Perch
- Sunfish
- Grass carp
- Catfish
- Minnows
What Fish Can Live With My Angelfish In A Tank?
Because angelfish are such a placid species, you have a lot of options in terms of tank mates. It is important to keep in mind that they may become aggressive with one another where mating is concerned, but on the whole, you shouldn’t have too many problems, especially if there is a strong female to male ratio.
- Gouramis
- Rasboras
- Corydoras
- Rainbowfish
- Peaceful barbs
- Discus – only in a larger tank where a consistent temperature of 82ºf can be maintained.
Conclusion
Angelfish and koi are both freshwater species but this doesn’t mean that they should live together. Both animals are placid and won’t typically get aggressive with one another if they do live in the same tank or pond. But while behavior won’t be an issue, the water conditions might be. Koi and angelfish require different pH levels, temperatures, and much more meaning that owners would find it extremely challenging to get the balance right for both of them.
You should keep your angelfish in an aquarium whereas the koi require a larger outdoor pond owing to the fact that they can get much larger.
