Many people experience the issue of their fantail goldfish fins turning black. The issue can be cause for immediate attention, or it can be completely harmless. It is important to pay attention to changes in behavior and eating habits of the goldfish.
Major changes in normal habits along with the changing color could be a sign of serious problems. In most cases, the black color is a sign the healing process has already begun, and further treatment to the goldfish is not necessary.
The most common reason that results in fantail goldfish fins turning black is from ammonia burns. Ammonia burns are caused from the tank not being properly cleaned. Food that is not eaten and fish waste causes toxins to build in the water. If the water is not properly filtered and cleaned often, the toxins can cause burns to the goldfish.
The black color is a sign the infection is healing, and cleaning out the tank properly will help ensure the infection will not return. In time, the goldfish should return to normal color.
It is also possible the tank is not large enough for the goldfish. Many people begin with a small tank or bowl when purchasing their first goldfish. The water can easily get stagnant if it not cleaned regularly. Toxins can quickly infect the tank and cause illness.
It is also hard to keep the temperature regulated in a small bowl. The small size of the tank can easily cause infections in goldfish and result in the fantail goldfish fins turning black. Simply investing in a larger tank can minimize this problem. Purchasing a 10- or 20- gallon tank is generally sufficient to ensure the goldfish has plenty of room to swim. It is also easier to install a filter system to a larger tank.
Finally, there is a very simple explanation for why fantail goldfish fins turn black. It is quite possible that there is nothing wrong at all. Goldfish are known to change colors. The change could be just a normal process for the goldfish.
If the fish is acting normally, the water is clean, and the water temperature is fine, there is probably no reason for concern. Still, if there is some concern, it is best to completely clean out the tank. A local pet store has products available to help rid toxins that may be present in the fish tank. Keeping a clean fish tank is the best way to help avoid unnecessary infections.