Betta fish are aggressive and predatory towards other fish, with the following specific behaviors:
Aggressiveness and Feeding Habits
Betta fish are naturally fierce and will actively attack fish of similar or smaller size, often inflicting harm or even causing death by nipping at fins. They have an especially high attack rate on small fish such as guppies and tetras, capable of disabling the target fish's fins within 48 hours and triggering tank infections.
Risks of Mixed Tank Keeping
High-risk combinations: When kept with fish like guppies, goldfish, or rummy-nose tetras, bettas will launch continuous attacks due to territorial awareness or resource competition, leading to a surge in ammonia levels and deterioration of fish health.
Low-risk conditions: Mixed tank keeping with faster-swimming species such as tiger barbs or mollies may be attempted only if the water volume exceeds 30 liters and there are sufficient hiding spots (e.g., aquatic plants, driftwood), with strict control over the number of bettas.
Breeding Recommendations
To avoid casualties, it is advisable to keep bettas alone. If mixed tank keeping is necessary, the following conditions must be met:
The size difference between target fish and bettas should be at least 3 times (e.g., arowanas, blood parrot cichlids);
Use a double-layer filtration system and maintain physical isolation;
Regularly observe fish behavior and promptly isolate conflicting individuals.
The aggressive behavior of bettas is closely related to their breed and living environment. Approximately 73% of failed mixed tank keeping cases stem from underestimating their aggressiveness.