During the day when water temperatures are relatively high, koi may feed aggressively. However, if temperatures drop sharply at night due to sudden weather changes or rainstorms, the rapid decline in water temperature disrupts the normal functioning of their digestive system, leading to indigestion (i.e., digestive disorder).
(1) Symptoms:
In the early stages of indigestion, symptoms are not easily noticeable. In the intermediate stage, affected fish may show loss of appetite, lethargy, constipation or abnormal feces, and thin, white, mucous-like feces trailing from the anus. In the advanced stage, the fish become listless, inactive, with closed pectoral fins and drooping dorsal and caudal fins. They also exhibit emaciation, a hard or overly soft abdomen, congestion in the abdominal wall, slightly red anus, and yellow fluid discharge when pressed. Death may follow shortly.
(2) Preventive Measures:
Adhere to the "Four Fixeds" (fixed time, location, quantity, and quality) and "Four Observances" (observe weather, water quality, fish activity, and feeding response) when feeding. Reduce feeding during sudden temperature changes.
(3) Treatment Methods:
In the early and intermediate stages, stop feeding the affected fish and allow them to bask in sunlight. Appropriately raise the water temperature and keep them in calm, slightly green water. If necessary, add a small amount of nitrofurazone or furazolidone to the water (0.1–0.2 grams per 50 kg of water). For koi that can still eat, feed artificial feed containing furazolidone or furazolidone analogs.
