Signs of an ailing Goldfish can be quite apparent if you observe closely. Their behavior might drastically change, showing signs of sluggishness or erratic swimming.
Other potential indicators include a lack of appetite, noticeable weight loss, blotches or lesions on the skin, rapid breathing, or unusual isolation. An alarming sign may be if your fish lies at the bottom or floats upside-down on the surface. Remember, timely detection and appropriate action are crucial to address any signs of illness in a Goldfish.