The mixed breeding of betta fish with other pet fish requires careful consideration of multiple factors to ensure that all fish can coexist harmoniously.

First of all, the size of the fish tank is crucial. Although betta fish are small in size, their aggressive nature means that a relatively large space is needed to reduce fighting. The recommended fish tank size is at least 40 centimeters or more, and it is best to be around 60 centimeters. This can provide sufficient activity space for betta fish and other small ornamental fish.
Secondly, the decoration inside the fish tank is also very important. Sufficient obstacles and aquatic plants should be set up to provide hiding places for fish and reduce direct conflicts. An environment with many obstacles helps to alleviate the aggression of betta fish and also provides a sense of security for other fish.
When choosing fish for mixed breeding, the character and behavior of the fish should be considered. For example, when betta fish are mixed with Rhodeus sinensis, gobies and other fish, intense fighting may occur because these fish all have strong territorial awareness and aggressiveness. In contrast, fish with faster swimming speeds such as guppies may be more suitable for mixed breeding with betta fish because they are not easily bitten by betta fish.
In addition, the number of fish for mixed breeding is also a consideration. If there are a relatively large number of betta fish for mixed breeding (about 20 or so), the fighting between them will be relatively reduced because each fish has its own territory and small group, thereby reducing direct conflicts between groups.
Finally, the filtration system of the fish tank is also essential to ensure good water quality and reduce the occurrence of diseases.
In conclusion, the mixed breeding of betta fish with other pet fish requires comprehensive consideration of the size of the fish tank, decoration, the selection and number of fish for mixed breeding, and a good filtration system to ensure that all fish can coexist harmoniously.