The Pet Directory Aquarium Article - How To Care For Goldfish (Carassius auratus)
How To Care For Goldfish (Carassius auratus)

As published in The Pet Directory NSW & ACT Edition
by Aquarium Industries

It has been estimated that a third of all ornamental fish sales in Australia are goldfish. These beautiful, hardy fish are usually the ones that launch people into the hobby. Goldfish in all varieties and sizes make wonderful easy to care for displays in shops, and their sales potential is almost unlimited.

Oranda Red
Fan Calico
Oranda Red

The ancient Chinese kept goldfish some 1600 years ago. The original wild, drab coloured fish were selectively bred until the beautiful clear bright colours of today’s fish were developed. The Japanese obtained some of these fish about 500 years ago and have developed some of the more unusual types of goldfish. Today there are dozens of different types. Even though they are different colours and have different body, tail and eye shapes, they are all the one species, Carassius auratus.

Oranda Red cap
Oranda Red cap
Panda Black and White

Goldfish are capable of reaching the grand old age of 20 years and attain a length of between 12 to 30cm, depending on variety. Red and black, and white and black (panda) goldfish are in the process of changing colour and will most likely turn all red or all white sometime in the future.

Customers often ask how to sex goldfish. Small goldfish are difficult to tell apart. Larger fish at about one year old can be distinguished fairly easily. Males develop small white tubercles along the leading edge of the pectoral fins. When in breeding condition the tubercles can also be noticed on the gill plates.

Goldfish in shops should be kept in large aquariums with plenty of surface area and in a relatively cool position. Algae growth on glass looks unattractive, so keep natural light to a minimum and wipe algae off glass regularly. If goldfish are over crowded or overfed the water will become cloudy and frothy (bubbles appear at the water surface). In extreme cases the fish hang at the surface, gasping (this is a sure sign of lack of oxygen). This is more likely to occur in summer, because as water temperature goes up, oxygen levels go down.

Goldfish are not fussy about the pH of their water but seem to prefer it between 7.0 and 7.5. However, extremely acid water is not tolerated. The addition of goldfish water conditioner is highly recommended, especially in soft water areas. Do not skimp on filtration, as goldfish are heavy feeders and produce a lot of waste. A power filter or at least a large box filter must be used to trap solid particles. A large (biological) filter is needed to break down toxic fish waste. Plenty of aeration and regularly cleaned filters all help keep water quality and oxygen levels up. Weekly 1/3 to 1/2 water changes are suggested in order to dilute nitrate and other waste products.

Goldfish are ideally kept at approximately 15oC-20oC, but can tolerate temperatures from near freezing to the low thirties.


A good staple food for goldfish in shops is floating granules. The small size is best, as this assures all fish get their fair share. Feeding floating granules, two to three times a day, in the right quantities is one of the major factors in keeping goldfish healthy and active. For variety, occasionally substitute flake food, and, more importantly, some vegetable material. Frozen “vegetable diet” is good, but if you can get duckweed, feed this several times a week. It is very rich in vitamin C, brings out the fish’s colour, and increases resistance to disease. Duck weed (Lemna minor) is a tiny floating water plant, which can be found massed together as a green carpet on the surface of still waters.

REMEMBER: If goldfish tanks are heavily stocked you must keep the quantity of food down at each feed and carry out regular partial water changes.

Care Sheet supplied by Aquarium Industries Pty Ltd

“How to Care for Goldfish” is an edited extract from Aquarium Industries’ Technical Notes.
AI Tech Notes covers all aspects of ornamental fish care and has been specifically written for Australian conditions. It forms part of the AI “We Care Support Program” and is available to AI clients. Images supplied by Jon Amato

Aquarium Industries
Actinic Aquariums Huge Range of Aquarium Goods. SpecialisedMarine Set Ups, UV Sterilizers, Lights, Ornaments & much more. Visit Actinic Aquariums today!
SUBMIT an Australian Pet Industry News Article to The Pet Directory!



Dog Real Food Diet for a Healthier and Longer Life


Stop your cat from spraying in just 7 days


Brain training for dogs


Raising Quails Made Easy


Naturally ready cat real food diet


cat language bible - what is your car telling you?

Follow The Pet Directory on Twitter The Pet Directory on Facebook