How to distinguish healthy fish from sick fish when raising goldfish?

Normal goldfish, the body surface is bright and clean, ups and downs freely, appetite is strong, abdomen is straight, tail fin is stretched. The sick individual swims alone, looks dull, does not eat after eating, has dim body color and more mucus on the body surface. If you carefully observe the body surface, there will be white spots or cotton-wool hyphae or bloodshot and red skin. The onset of fish ponds, fish gathering in the corner of the tank or crowded together are all precursors of the onset.

Normal goldfish, bright red gills, gill cover open freely. In sick individuals, the gill filaments are dim and white, or rotten or have flocculent hyphae attached, the gill cover is unable to open, and the pool edge or corner is sluggish. The fins of healthy goldfish are well developed and can stretch freely, while the fins of sick goldfish are prone and unable to stretch, and there are white spots or congestion on the fins. If there are bubbles on the fin, it belongs to hot tail, and it will disappear as long as it is replaced with new water. Goldfish have sarcomas, which are bright and plump, and sick individuals, which are atrophied, dull, or show signs of decay.

It is hot in summer, and the observation time is mostly concentrated from midnight to dawn, mainly to observe the floating head of goldfish, inject water or change water in time, or turn on oxygen-increasing equipment.