Many new fish owners worry they might not know if something is wrong with their much loved pets. Unlike cats and dogs, they can’t signal to you that they may be injured or reacting badly to changes in their environment, but there’s no need to worry…if you pay attention to how your fish looks, you are very likely to be able to spot any warning signs fairly early on.
If your Goldfish is starting to turn black, try to pay attention to how much of their body is affected, and how quickly the change is taking place. You should also think about your feeding and cleaning routines, and other environmental factors – this will help you narrow down what the underlying cause can be – there may be a simple solution to the problem that will help your fish stay happy and healthy, or it may be a natural change that needs no action on your part.
Do I need to worry?
While some changes in color can be natural and no cause for concern, turning black can indicate your fish is in trouble and you may need to make a few changes to see if you can help them.
As always, if you’re very concerned, especially if your fish is showing other symptoms along with the color change, you should seek specialist advice as soon as possible.
In most cases, there’s no need to panic if you notice your fish turning black. We’ve come up with a few of the most common reasons for your fish turning black to help you work out if it is a natural change, or an issue that needs your attention.
Changes to suit the environment
All fish have different cells in their skin, and some produce a black pigment called melanin. If you place your fish tank against a dark back drop, for example dark wallpaper, or if you decorate your tank with lots of dark items or rocks, then your fish may begin to produce more melanin.
If natural changes in color are the reason your fish is turning black, you should notice the change on patches of the body, or in the fins. This type of color change is completely natural and normal, and is nothing to worry about.
It’s in the genes
Many Goldfish owners will opt for a less expensive breed of the pet, and are happy to purchase a ‘mix breed’ to take home to their aquarium. If this is the case in your tank, you’re more likely to see changes to the color of your fish. While most of these color changes happen in the first year of life, you may still notice changes in coloring as your fish gets older. This can include darker or black patches appearing, but also lighter areas showing themselves too.
If you have a ‘purebred’ goldfish in your aquarium, any color changes you notice are likely to be more subtle, and follow similar patterns to those of the parents. It’s still possible to notice changes in color though, especially while the fish is still young, so if you want to have a fish for its particular color, you may want to buy a slightly older one to increase the chances of that being the color they keep as they mature.
High ammonia levels in your fish tank can cause problems for the health of your fish…but the good news is, it’s fairly easy to fix this problem.
Ammonia is created as a by-product from the waste produced by your fish, but the levels they produce themselves is not harmful to their skin. The issues arise when excess food is also left in the tank to rot, as more ammonia is produced from this.
If high ammonia levels are what is causing your fish to turn black, this means the level has already been high and has caused small burns on the skin of your fish. As the ammonia levels drop, the damaged skin will start to heal, and this is when the black patches on the body will appear.
It is vital you don’t leave too much food in your fish tank – black patches on your fish mean that at least their skin has had time to heal from an ammonia burn. If the levels of ammonia are constantly too high, the skin won’t heal and the black marks won’t appear, so the damage may go unnoticed for a much longer period of time.
To help stop the initial risks of ammonia burns, remember to give your tank a thorough clean regularly, as removing some of the old water will help keep the ammonia levels low.
Black Spot Disease
This is a very rare problem, especially in adult fish, but it is still worth a mention. Black spot disease will only be the reason for your fish turning black if you have water snails in the same tank, as they are the ones that carry it.
If you keep your goldfish in an outdoor pond rather than an aquarium, you’re more likely to encounter this disease, as fish can catch it from bird droppings coming into contact with the pond.
Because this parasite affects the skin of a fish when their eggs try to burrow in, your fish will start to form hard cysts to protect themselves – these will look very dark or black. Another sign to look for if you feel this is the problem, is that your fish may start to flick themselves because of the irritation caused.
If you think the reason for your fish turning black may be black spot disease, you need to remove the snails from the tank for a while to try and stop the parasite from continuing its life cycle.
The most common reasons behind a goldfish turning black are very natural and are no cause for concern, but it’s always worth considering the risk of disease and checking the ammonia levels in your tank. Both of these issues can be solved fairly quickly and easily, and will make a huge difference to the life and health of your fish…so double check if they could be problems in your tank before putting any black spots down to natural changes in the skin of your fish.