Ammonia burns are the most common reason that goldfish turn black. High ammonia content in fish tanks causes irritation and trauma to the goldfish's fins. Ammonia burns are white in color and turn black as the goldfish heals.Know More
Additional reasons for a goldfish to turn black include ingestion of colored fish flakes and genetics. Many goldfish possess a random mix of color genes, which in turn can lead to color variations.
High ammonia levels in a fish tank are easily remedied with a 25 to 50 percent water change. Ammonia levels tend to fluctuate when there is undigested food or fish droppings in the water as these items emit excess ammonia while decomposing.Learn more about Aquatic Pets
Although there is little proof, rare cases have indicated the possibility of cannibalism in goldfish. The National reported an incident in which goldfish ate other fish after an earthquake, leaving them of food for an extended period of time.Full Answer >
Swim bladder disorder is the most common reason for a betta fish to float on its side. There are numerous causes of swim bladder disorder, including disease, physical trauma, parasites, environmental factors and constipation.Full Answer >
According to FishChannel.com, determining the gender of a goldfish can be difficult, as the fish are weakly dimorphic. However, depending on when the fish are checked, it can be possible to determine their gender based on physical differences.Full Answer >
Goldfish swim upside down when they have swim bladder disease. Goldfish and other species of fish may also swim sideways or do not have the ability to swim to the bottom of the tank if they have this disease.Full Answer >