Koi fish cannot be mixed with arowana because their body shape, habits and personality are different:

1. Habits: Koi fish is a cold water fish and can accept a wide range of water temperatures. They can grow in water temperatures between 18 and 32 ℃, and are not particularly sensitive to environmental changes. Arowana is a tropical fish, which likes a higher water temperature and needs to grow in the water temperature between 28-30 ℃, and they are sensitive to environmental changes.

2, body shape: Koi and Arowana are also different in body shape. Koi is a medium-sized fish, and its body length is about 30-40 cm in adulthood. Arowana is a large fish, and its body length is between 60 and 120 cm in adulthood. There is a big difference in body shape between them, and koi may be bullied if they are mixed together.

3. Personality: Koi and Arowana have different personalities. Although Koi is lively, compared with Arowana, its aggressiveness and attack power are weak. In addition, arowana has a strong sense of territory. If koi is raised with them, they are likely to bite or kill koi.

Koi fish can mix with goldfish, wheat ear fish, etc. They are lively and have a cheap mouth, and like to bite other fish. Therefore, fish with similar size but gentle personality are not suitable for raising together. However, their aggressiveness and attack power are not strong, and they are not suitable for raising with fierce fish, so there are not many fish suitable for raising with them.