Clear water is not always an indicator of healthy water. Research by professionals indicates that certain harmful pathogenic bacteria can have a strong clarifying effect on water. This can lead to situations where a pond appears crystal clear, yet koi still fall ill.
Therefore, relying solely on visual clarity is insufficient. It is crucial to regularly test key water parameters—such as ammonia, nitrite, nitrate, dissolved oxygen, and pH—to ensure they remain within safe ranges. Many toxic substances (like ammonia and nitrite) are invisible, and clear water can sometimes mask underlying chemical imbalances, low oxygen levels, or specific bacterial blooms that stress or directly harm fish. Consistent water testing, alongside observation of fish behavior, provides a far more accurate picture of the true pond environment.
