Goldfish are typically thought of as great pets for beginners. However, they take a bit more work to keep happy than most people realise. Their amount of food and water quality is essential to keeping them alive and in good health. There are diseases that goldfish can contract, the most common is known as Goldfish Fungus.
What is Goldfish Fungus
Saprolegniosis, commonly known as fungus, is a disease that only attacks fish whose health has been compromised in some way. A fish can only catch this if it has been injured or contracted a bacterial or parasitic disease. The fungus always exists in fresh water, but healthy fish have a slime coating on their outer layer which controls it naturally. Once the fish has contracted the fungus it works from the inside out, essentially consuming the fish and exposing underlying muscles and bone as the dead skin falls away. The condition strips the fish of its minerals and energy to heal, eventually the fish will die from osmotic shock.
The fish will start to display areas that seem to be of a cotton-like texture. These could be whole sections of the body, or small dots. They will be either white, green, or brown.
The most important thing to do is take preventive action by keeping the aquarium clean, and absent of sharp objects, so that your fish stays healthy. But, if it contracts the fungus there are steps you can take to save the fish. The fungus does spread, so if there is more than one fish in your tank it's important to remove the infected fish from the others as soon as possible. There are anti-fungal treatments that are available at pet stores to treat the fish; usually this works. You can also put salt in the water to reduce the chance of the fish getting osmotic shock. The amount of salt should be 30 grams to 1 litre of water. Do not use table salt as it has iodine in it.