A friend asked me whether goldfish and koi can be kept together. This question is actually very common among beginners when they first start with coldwater fish. First of all, if you just want to keep fish for entertainment and to enjoy the process, there’s really no big deal. You can buy a few small koi or goldfish and put them in an aquarium, which is completely fine. However, if you wish to keep fish more professionally and seriously, I still do not recommend mixing koi with goldfish.
Size Difference
The first point is their significant size difference. Goldfish, even when fully grown, will not be very large in size. Koi, on the other hand, are well-known for their potential to grow quite large if well cared for. Keeping them together will not only look incongruous but also, koi may bully goldfish.
Activity Space and Filtration System
The second point is that koi have a large appetite and produce a lot of waste, thus requiring a relatively large activity space. To meet the needs of koi, the filtration system must be very powerful. However, using such a powerful filtration system for goldfish would be too much for them. For instance, some goldfish varieties such as butterfly tail, pearlscale, and crimson crown have poor swimming abilities and are not suitable for being kept in koi tanks.
Feeding Difference
The third point is the significant difference in their feeding habits. For example, koi have larger mouths compared to goldfish. When feeding, due to the limitations of the aquarium, it is not possible to feed them separately. If larger food is provided, goldfish may not be able to eat it, while koi can easily grab the food. Therefore, if they are mixed together, goldfish may hardly get enough food.
Finally, I would like to share some personal opinions. I always feel that goldfish and koi together are not particularly aesthetically pleasing. Therefore, I suggest that everyone keeps them separately. If you want to keep koi, it is recommended to prepare a slightly better aquarium and use equipment with stronger filtration effects. If you want to keep goldfish, it is best to choose an aquarium with a slightly shallower water level.
Original article by KPTer, if reproduced, please cite the source: https://www.kaipet.com/en/goldfish-koi-advice-professional-aquarists
Comments(2)
This is really insightful! The reasons for keeping them separate are very clear. What are some early signs of stress for goldfish to watch for?
@CriticX：感谢您的洞察力和提问！很高兴这篇内容能为您带来启发。关于金鱼压力的早期迹象，通常包括鳍夹紧、活动减少、食欲不振或体色变化。建议关注这些细微变化，并确保它们有一个适宜的环境。