Why is my gold nugget pleco's color fading? Is it a sign of illness?

Thanks for reaching out. The most important thing you can do is maintain optimal water quality, and this means getting a test kit and testing frequently. Diet is important, and all fish have a dietary requirement for vitamin C. Vitamin C is not stable in fish food for more that a few months, so write the date of purchase on the can of food, and discard after 3 months. It is also recommended to alternate brands of food, as they are all slightly different. Since they have an exoskeleton, the only easy way to measure body score is around the belly. If concave, too thin. Determining illness is tough, so visualizing eating and activity, and comparing it to the past. Good luck.

Check the water temperature. This species does best between 68 F and 77 F. Low temps can affect appetite in fish. He may be near the heater for warmth. Check the water chemistry as well. Use a home test kit or submit a water sample for testing. Most pet stores will do this for free or for a small fee. Aim for 0 ppm ammonia and nitrites with a nitrate level of 20 ppm or less. Partial water changes can be done to stabilize chemistry if indicated. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. If it is a "new" tank, there may not be enough food/algae on the bottom for it. Use sinking pellets or toss in some vegetables or greens. Be sure to remove any uneaten food after 24 hours to prevent it from fouling the water.

Check the water chemistry. Two goldfish can quickly overwhelm a tank with their large bio load. Aim for 0.25 ppm (parts per million) or less ammonia, 0 ppm nitrites and 40 ppm or less nitrates with a temp between 65 and 72F. If water chemistry is good, it is possible the red marks are from the pleco. They are notorious for sucking the slime coat off goldfish leaving red marks and wounds. Partial water changes, 30-50%, using aged or conditioned water that is temperature matched are safer and less stressful than complete changes. Give the antibiotics time to work. You can add in plain aquarium salt (NOT table salt) to aid healing. Dissolve one teaspoon per gallon of water in a cup of tank water and gently pour it in the tank. Perform partial water changes after 10-14 days to reduce salt content.

Thanks for reaching out. Did you use tap water and dechlorinate prior to the water changed? The dechlorinating solutions do not work immediately can take several hours to lower levels of chlorine and chloramines (typically in tap water). Did you match water temperatures? Temperature shock of even a few degrees can lead to death or depressed immune system. A veterinary visit is recommended for the pleco to assess health and recommend treatments. Good luck.

Loss of color in fish can be a sign of severe stress. Stress can be brought on by disease, poor water quality, over cleaning the tank (too frequent or too large water changes), over aggressive fish, poor or inadequate nutrition, being moved, over crowding, and a host of other situations. I recommend that you start by reviewing your water quality and tank environment. How are your water parameters? Review how often you do water changes and how much water you change at one time. How much are feeding? Could you be over or under feeding your fish? Is there a bully fish in your tank - a fish that chases or aggresses against other fish. Are the number of fish in your tank suitable for the size of the tank? Look for signs of disease. Fish can suffer from bacterial, viral, fungal, protozoal, and parasitic infections, but not all species of fish suffer from the same illnesses. You can find charts of fish diseases in books or on the web to help you narrow down what illnesses might be affecting your fish. Treatment of disease will be based on determining what type of organism is making your fish ill. To prevent illness in fish, maintain high water quality, avoid over crowding your tank, and quarantine new fish before introducting them to your tank.

Check the water temperature. Low temps can affect appetite and digestion in fish. Angels do best between 78 F and 80 F. You can soak food in garlic juice to stimulate his appetite. Next, check the water chemistry. This can be done using a home test kit or by submitting a water sample for testing. Most pet stores will do this for free or for a small fee. Confirm 0 ppm ammonia and nitrites with nitrates at 40ppm or less in a tank with live plants or 20 ppm or less in an unplanted tank. Partial water changes can be done, if indicated, to stabilize chemistry and/or maintain water quality. use only aged or conditioned water that is temperature matched to prevent stress or shock. Although they do best in slightly acidic and soft water, they are quite adaptable. Fast him for 2-3 days then feed bits of cooked and shelled green peas. if he is constipated then this should him him get regular again. A broad spectrum parasite medication, such as PraziPro, should be considered. You can find it in the aquarium section of the local Petco. Follow label directions carefully.

Check the water chemistry. The discoloration could be due to elevated ammonia levels which can cause "burns". Use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Perform partial water changes to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. The Neons (blue fish) appear to be infected with Ich, a parasite. Treatment is possible with commercial products found in the local Petco. Follow label directions carefully. You will need to treat the entire tank until all traces are gone. Removing a lump from your fish on your own is never recommended. You can cause severe injury. Most broad spectrum antibiotics (Kanaplex, Maracyn, Maracyn 2, etc.) found in the aquarium section of the local Petco should help treat or prevent infection. Choose one and follow label directions. Remove the carbon filter insert during treatment if indicated. Maintain pristine water quality via filtration and regular partial water changes to aid in recovery. You can feed frozen worms, just thaw then first in a small cup then place them in the tank.