1. Increased Waste: Fish produce waste, and doubling the number of fish means doubling the amount of waste. This excess waste can cloud the water, making it appear murky.
2. Bacterial Bloom: The increased waste provides a feast for bacteria in the water. These bacteria can multiply rapidly, leading to a bacterial bloom which can make the water cloudy.
3. Uneven Filtration: If your filter isn't strong enough to handle the increased bioload (the amount of waste produced), the water can't be filtered properly, leading to cloudiness.
4. Disturbance of Substrate: Adding more fish can disrupt the substrate (gravel or sand) at the bottom of the tank. This disturbance can release particles into the water, making it cloudy.
5. Overfeeding: Overfeeding is a common cause of cloudy water. Excess food breaks down and contributes to the waste that causes cloudiness.
6. Stress: New fish may be stressed, which can lead to increased waste production and cloudiness.
7. Water Changes: If you didn't do a proper water change before adding the new fish, the water quality may have already been compromised, making it more prone to cloudiness.
What to Do:
* Increase Filtration: Ensure your filter is powerful enough for the new bioload. Consider upgrading to a larger or more efficient filter.
* Reduce Feeding: Feed your fish less, only what they can consume in a few minutes.
* Perform Water Changes: Do regular partial water changes to remove excess waste and maintain water quality.
* Check Water Parameters: Monitor ammonia, nitrite, and nitrate levels to ensure they are within safe ranges.
* Clean the Substrate: Vacuum the gravel or sand to remove any accumulated waste or debris.
* Monitor New Fish: Observe the new fish for signs of stress and adjust your care routine accordingly.
Note: If the cloudiness persists or if you notice any unusual behavior in your fish, it's best to consult a veterinarian or an aquarium specialist for further guidance.