It is a common phenomenon that koi fish bite other fish, which may be caused by various reasons. Here are the main reasons and the corresponding solutions:
1. Insufficient Breeding Space
- Reason: If the fish tank is too small, koi fish may bite each other due to competition for territory. Fish need enough swimming space; otherwise, they will feel stressed, leading to aggressive behavior.
- Solution: Ensure that the size of the fish tank matches the number of koi fish to avoid overcrowding. You can refer to the following breeding density: for a fish tank with dimensions of 60×30×30 (length×width×height, in appropriate units), 4 to 6 koi fish with a body length of 5-10 centimeters can be raised; for a fish tank with dimensions of 120×60×60, 20 to 40 koi fish with a body length of 5-10 centimeters can be raised.
2. Water Quality Issues
- Reason: Deterioration of water quality can lead to the growth of bacteria or pathogens on koi fish. They may bite each other to remove these harmful substances.
- Solution: Change the water regularly and clean the fish tank to keep the water quality clean. You can use a filtration system or a sterilization lamp to improve the water quality.
3. Competition for Mates during the Breeding Period
- Reason: During the breeding period, koi fish may bite each other due to competition for mates, especially when the male-female ratio is uncoordinated.
- Solution: Adjust the male-female ratio to ensure harmonious coexistence. You can add decorations or aquatic plants to the fish tank to provide more hiding spaces for koi fish.
4. Adaptation Problems of New Fish
- Reason: Newly added koi fish are not familiar with the fish in the original tank, and they may bite each other due to not adapting to the new environment.
- Solution: Isolate and observe the new fish before adding them to the tank to help them gradually adapt to the new environment. You can use an isolation tank to assist the new fish in the transition.
5. Other Reasons
- Competition or Stress: Koi fish may bite other fish due to competition for food or territory, especially when the space in the fish tank is limited or the number of fish is too large.
- Curiosity and Exploration: Koi fish may sometimes be interested in fish of different colors, resulting in the phenomenon of biting tails.
Summary: Koi fish biting other fish is usually related to factors such as the breeding environment, water quality, the breeding period, and the adaptation of new fish. By optimizing the breeding space, keeping the water quality clean, adjusting the male-female ratio, and properly handling the addition of new fish, this phenomenon can be effectively reduced or avoided.