If you’ve noticed one or more of your goldfish is turning black, it is likely an indicator of a serious health issue. One of the most common causes behind the blackening of goldfish scales is ammonia poisoning. High ammonia levels are a common issue that aquarists have to deal with, with regular testing and water changes usually enough to keep on top of the issue. However, if you’ve relaxed your approach to water care, ammonia levels can creep up to dangerous amounts.
What Causes High Ammonia Levels?
There are several contributing factors to high ammonia levels in fish tanks. Waste that your fish generates in the form of faecal matter and urine can eventually lead to high ammonia levels when this matter breaks down and dissolves within tank water. If you are overfeeding your fish, you may also be contributing toward high ammonia levels. Uneaten food that is not removed from tank water will eventually dissolve, with the organic matter eventually transforming into harmful ammonia.
When ammonia levels are high enough, you may start noticing black spots and patches on the skin and scales of your fish. These black marks are actually ammonia burns. While the appearance of black spots on your goldfish can be alarming, it is by no means a death sentence. Once you have remedied the ammonia issues with tank water, the injuries your fish have sustained will begin to heal. However, if the damage is significant enough, black spots may remain forever.
Other Causes of Black Marks
While ammonia is the likely culprit behind black marks on your goldfish, it is by no means the only cause of the issue. Black spot disease is another potential cause, although this ailment is fairly rare. The cause of black spot disease is generally courtesy of fellow aquatic tank mates. If you are keeping aquatic snails within your tank to keep on top of algae growth, they may be the reason behind black spots on your goldfish.
Unlike ammonia scars, these black spots are actually the result of parasites that have spread from animals like snails to your fish. The black spots themselves are actually the result of your goldfish growing cysts to protect themselves from parasite, rather than scars from the parasites themselves. If your goldfish are showing evidence of black cysts, you should immediately remove any snails from your tank.
Another potential cause of black marks could be high stress levels. Most goldfish don’t respond well to rapid changes in their environments, so you should ensure you are maintaining a stress-free environment for them. Avoid climatic water changes that might shock your fish species. You should also be careful about introducing new tank mates into the mix. While solitary fish will usually cause no issues when introduced, a larger group may disturb the status quo considerably.
Will Black Goldfish Recover?
This is all depends on the root cause of the discolouration. If black spots are the result of ammonia poisoning, fish are unlikely to recover their natural colours during their lifetime. The same applies to any diseases and genetic ailments that might have lead to blackening of skin and scales. However, if stress or feeding issues are the reason behind the discolouration, goldfish may return to their natural state once the root causes have been remedied.