How do fish breath under water?

• Fish take the oxygen that they need from the water in which they live, the pink gills, which lie behind their heads and move in and out regularly, are the equivalent of our lungs, drawing oxygen from the water into the fishes bloodstream.
• It is important that the water you keep your fish in is kept clean and fresh, otherwise the fish could get into trouble due to lack of oxygen. The water should be changed regularly and the water can be kept topped up with oxygen by bubbling air through it using an air pump

How long do goldfish live?

• Goldfish have an average life span of between 5-10 years. The oldest known goldfish lived to 41 years of age

How big do goldfish grow?

• The average goldfish is fairly small but they can grow up to a foot in length

How often should I feed my fish?

• Overfeeding is one of the most common and harmful errors in caring for fish. The food that is not eaten turns into toxins in the tank
• Feed your fish small amounts once or twice a day, if they eat the food in 2-3 minutes and are looking for more, add another small pinch

What are the signs of fin rot and what causes it?

Usually one or more fin becomes frayed and sections of it erode off and disappear. There are several causes including:

• Trauma
• Poor water quality - ensure the following levels:
  - Oxygen >5.5 mg/l
  - Ammonia < 0.01 mg/l
  - Nitrate < 40mg/l
  - Nitrite <0.125 mg/l
• Avoid chemical contamination
• Some fish are pH sensitive
• Bacterial infections
• Protozoal infection
• Ectoparasites

Various treatments can be used to treat the condition.

What causes spots on fish?

One of the common signs of disease in fish is the appearance of spots on the surface of the skin. They come in different colours that can be helpful in identifying the cause:

Black Spot
Small black or brown spots up to 2mm in size on the body or fins caused by a worm. It affects coldwater fish including Carp, Goldfish and Tench
Cryptocaryon (also called Salt Water Ich)
This is caused by a marine parasite and causes grey-white nodules about 2mm in size, it irritates so the fish rub themselves against objects
Fish pox (also called carp pox or skin papilloma)
Caused by a virus, it forms small white spots that are opalescent. These merge, causing large patches and later they turn reddish-grey, it mainly affects carp
Ich (white spot)
This is caused by a parasite, it appears as small pinhead spots on the fins and body. It affects all freshwater aquarium fish and the fish rub themselves against objects
Ichthyosporidium
Caused by a fungal infection, small white nodules appear on the skin, often fish have a swollen abdomen as well
Inflammation
Reddening of the skin all over the body is associated with bacterial septicaemia, the fish can become very ill and die very quickly
Lymphocystis (also called cauliflower or raspberry disease)
Small white nodules occur on the skin and fins and grow to 2mm size tumours. This is caused from a virus and often the fish will die from it
Nodular disease
Sporozoan infections cause cysts (containing the parasite) they vary in size from pinhead to pea-size spots. A wide variety of fish are affected
Yellow Grub
Similar to black spot it causes black or yellow spots in tropical fish.

Treatment

Some of the above conditions can be treated relatively easily, others cannot. Some of the diseases can survive in the aquarium and re-infect fish later. If you have a fish showing these signs consult your vet as soon as possible.