black spots on all of my goldfishes?

Question

All of my goldfishes have black on their fins and tails and then one of them has it on its fore head and around it's mouth and the other 2 have it around their mouth. I was wondering what this is? And how to treat it?

Answer 1

Have they always had these spots? Goldfish sometimes start with more black coloration, then change to gold or yellow over time - this is a natural change and shouldn't be a cause for concern.

If this is something that's developed since you've had the fish, that's another story. Black patches are usually an indication that they've come into contact with an irritant in their water.

Do you know the ammonia or nitrite levels in your tank? If it's been running less than 2 months, one of these (especially the ammonia) is usually the cause - you can have your pet store test a sample of your tank water to confirm this if you don't test the water yourself. This can be helped by doing regular water changes (at least 25-30% each week, or 15-20% twice a week).

Also, do you use anything besides a conditioner that removes the chlorine/chloramine that your public water supply adds as a treatment - this could include salt, medications, algae killers, etc.? If you do water changes, do you add back the amount removed by the water change only? (I need to ask because I once help a person who was adding the dose for the entire tank volume each time - that overdosed the fish and caused a "chemical burn".) Only add the amount for the volume of water removed, unless your directions specifically say otherwise.

Also, if you use tap water, do you know which of chlorine or chloramine is used to treat your water supply and do you use the proper product to remove it? If chloramine (a combination of chlorine and ammonia) and you use a product that only removes chlorine, or "breaks the chloramine bond", this releases ammonia into the tank. A call to your water authority will help you with this.

Even if the irritant is removed, it may take 2 weeks or so for the patches to completely disappear.

Answer 2

Usually these spots are seen as the fish is healing from ammonia surges. The area that was burned will turn black and this is the healing sign. The spots should fade within about 2 weeks. Orange Goldfish will sometimes turn black on their back and sides. After about 7 days the patches disappear and the fish appears orange. This is known as "Melanophore Migration" and is usually caused by any type of chemical irritant or traumatic injury. Some very common causes: high level of ammonia, low pH, flukes, or ick. The black color will not show up until the irritant is removed and the skin begins to heal. However if there are snails in the tank or the fish are living in ponds you should read below.

These spots could be from the pigmented cysts that contain the larval stage of a trematode intestinal fluke. Symptoms: Small black or brown spots up to 2 mm (0.08 inches) across. These spots appear on the body and fins of the fish and sometimes on their mouth and eyes. Treatment: Modern anti-parasite treatments should kill the parasites. The spots once formed may remain on the fish.