Why is my goldfish losing color? Is it normal for aging fish?

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.

Most of the time this is related to stress and absence of ''hiding places'' or inappropriate size of the tank. Otherwise could be completely normal. Please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.

Elevated ammonia levels can result in "burns" which may turn fins and scales black. Use a home test kit or submit a water sample for testing. Most pet or fish stores will do this for free or for a nominal fee. If ammonia levels are elevated, daily partial water changes, using aged or conditioned water, can decrease ammonia to safe levels (0.25 ppm or less). StressCoat or plain aquarium salt (NOT table salt) can aid in healing. Dissolve 1 teaspoon of salt per gallon of water into a cup of tank water and gently pour it into the tank. Confirm adequate filtration. The filter should be rated for at least twice the volume of the tank. You can change 20-30% of the tank water every couple of weeks. Use only aged or conditioned water that is temperature matched to prevent stress or shock.

Thank you for the picture - I am unable to tell if the tail is just turning transparent, or if portions of it are missing. If it is truly just a color change, and there are no other problems with C.G. or the other fish, it may just be that he is going to become a different color. If the tail has missing portions, that is more likely to be caused by an infectious problem (such as bacteria, fungi, parasites). I would recommend evaluating your water quality parameters, as you eluded to in your question. Then I would monitor the tail, and if there are portions missing, I would recommend having him evaluated by a veterinarian. They can take samples of the area, as well as from the skin and gills to evaluate for parasites and other organisms.

Add some protein to his diet. This can be in the form of live, frozen or freeze dried blood worms or blackworms. You can also use your preferred search engine to look for "earthworm sticks" to feed him. Check the water quality as well (hardness, pH, etc.). Make adjustments as needed. Low water temps may cause stress and illness. Check your tank heater and temperature.

That is not a good sign. This basically means that your fish is not feeling well. The reason for this is usually either water quality or a temperature problem. You will need to have your water quality checked or check it yourself, and make sure that the thermometer is working and the water temperature is appropriate for the type of fish you have. Check water chemistry using a home test kit or by submitting a water sample for testing. Aim for 0 ppm ammonia and nitrites with a 40ppm or less nitrate level. Perform partial water changes to stabilize chemistry and maintain water quality. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Observe your fish for spots, wounds, blood spots or similar signs and if that happens ask us again, preferably with a good photo of your fish.

This could be ammonia burn. Check the water chemistry. 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 a nitrate level of 20 ppm or less. Partial water changes will be needed to stabilize chemistry. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. Goldfish are cold water fish and do best between 65 F and 72 F. When using an ammonia reducing product, be sure to test the water after treatment but before pouring the treated water into the tank.