Do your fish seem less flashy than usual? Don't worry. As fish age, their vibrant colors often lose their luster. For example, the fanlike fins of black skirt tetras usually fade to gray as they mature.
Inadequate light exposure also can cause your pal to look less vivid. Angelfish, for example, won't develop complete stripes or spots without sufficient lighting. And cooler water temperatures may cause colors to darken.
But medical conditions might also be the culprit. Some diseases darken your fish, while others - such as anemia from bleeding, red blood cell (RBC) destruction, and kidney or spleen disease - can give your pet a washed-out look. Other causes of anemia include aeromonas infection, vibriosis, or mycobacteriosis, a chronic disease that invades the kidneys.
Parasites can also cause anemia if they drink too much of your fish's blood. With fewer RBCs to carry oxygen through the circulatory system, anemic fish develop anoxia (oxygen deficiency) and struggle to breathe. If you notice a rapid color change or pale gills, consult a fish veterinarian immediately - your fish's life is in jeopardy.
What You Can Do at Home
If your fish suddenly loses color, watch closely for other symptoms. Weight loss, appetite loss, and lethargy may indicate anemia from a parasite infection, internal tumors, or cancer. Bleeding fins and skin may indicate aeromonas infection or vibriosis. Fish with abdominal bloating may suffer from kidney disease. Consider consulting a fish specialist or a qualified fish veterinarian if you notice any of these symptoms.
If a medical condition is causing your fish's brilliance to fade, your quick response may restore them to their former glory.