Healthy koi are active, alert, and swim smoothly without signs of distress. They should have bright, consistent coloration, intact fins, and clear eyes. When feeding, healthy koi eagerly come to the surface and eat with enthusiasm. Their bodies should be free of visible parasites, ulcers, or white spots, and their scales should lie flat against their skin.
Unusual behavior, such as rubbing against objects, gasping at the surface, floating awkwardly, or isolating from the group, can be early signs of illness or poor water quality. Cloudy eyes, frayed fins, or sudden changes in appetite are also red flags. Regular observation during feeding times is one of the best ways to monitor their condition. Testing the pond water weekly helps ensure parameters like ammonia, nitrite, and pH remain stable, which plays a major role in keeping koi healthy. If something seems off, it's important to act quickly by checking water quality first and consulting a koi health resource or specialist if necessary.
