For simplicity’s sake, Goldfish may be divided into the ‘standard’ and ‘fancy’ varieties, with both potentially reaching 20-30 cm in length (8-12”) and living up to 20 years if properly cared for.
Although they are one of the most popular fish in the aquarist’s trade, goldfish are sadly often mistreated by those that simply don’t understand the aquarist hobby. Usually believed to require only a small bowl and expected to live for a year or two, goldfish are actually very large fish that can live for decades if properly cared for. They are a very hardy fish that can tolerate the kind of mistakes one could expect from a novice, but this hardiness has likely led to the belief that they naturally have very short lifespans, as they may show few signs of stress until conditions become deadly. They are a low maintenance fish, but this does of course not mean ‘no maintenance’. If you treat your fish pet with the same basic care an aquarist would for any other fish, you should enjoy many years of companionship with these stunning and surprisingly intelligent fish.
Originally hailing from East Asia, goldfish are now found all over Asia, Europe and North America, where they are considered an invasive pest species. They prefer slow-moving freshwater in cooler climates but can tolerate even muddy low oxygen waters.
Behavior/Compatibility for Goldfish
Goldfish are a placid, confident fish and are (despite common belief) actually quite intelligent. They are known to interact with their owners and have been shown to retain learned behaviours for up to three months. They are a great community fish that will get along well with their own kind and rarely cause a problem for suitable tankmates. However, finding a suitable tankmate can be quite difficult for several reasons. Firstly, goldfish (particularly the fancy https://livefish.com.au/freshwater/goldfish/fancy-goldfish varieties) are incapable of defending themselves and are highly susceptible to bullying, fin-nipping behaviours. Fancy https://livefish.com.au/freshwater/goldfish/fancy-goldfish varieties can easily become stressed when paired with fast-moving, boisterous fish, and should not be paired with the standard goldfish varieties like the comet https://livefish.com.au/freshwater/goldfish/comet-goldfish and wakin goldfish https://livefish.com.au/freshwater/goldfish/wakin-goldfish. Other factors you will need to consider is the goldfish’s tendency to attempt to swallow whatever fits in its mouth and their need for lower temperatures. You should pair your goldfish only with medium-sized, placid, cold water tankmates such as rosy barb https://livefish.com.au/rosy-barb-3cm, platys https://livefish.com.au/freshwater/platys and zebra danio https://livefish.com.au/zebra-danio-3-5cm. Giant danios https://livefish.com.au/giant-danio-3-5cm are also acceptable, but not for the poor swimming fancy goldfish varieties.
Housing Goldfish and Tank Set-up Tips
Goldfish can grow up to 20cm (8”) in the fancy varieties and 30cm (12”) in the elongated common variety. Unsurprisingly, the classic ‘goldfish bowl’ is highly unsuitable for the well being of these creatures. Initially, a 75 litre (20 gallons) will be fine while your pets are still young, but you will eventually need to upgrade to at least 114 litres (30 gallons) tank for the slow swimming fancy varieties and 200 litre (55 gallon) for the more active comets and common varieties. There should be some water movement and the water should be well oxygenated. Longer tanks are better than tall ones, but avoid low boy tanks for goldfish. The below tables represent the required tank sizes for adult goldfish. Although pairs are certainly preferable, goldfish can be kept alone, so the tables will begin with a single fish.
Recommended Max Fish Count Tank Volume 1-2 Common Goldfish 200 litres (55 gallons) 3 Common Goldfish 227 litres (60 gallons) 4 Common Goldfish 283 litres (75 gallons) 5 Common Goldfish 378 litres (100 gallons) Recommended Max Fish Count Tank Volume 1-2 Fancy Goldfish 114 litres (30 gallons) 3 Fancy Goldfish 150 litres (40 gallons) 4 Fancy Goldfish 265 litres (70 gallons) 5 Fancy Goldfish 340 litres (90 gallons)
Goldfish are curious feeders and will often sift through the substrate by picking up small rocks or shells. For this reason, you should avoid any sharp gravel but you may opt for either medium to small rounded gravel or sand https://livefish.com.au/accessories/gravel-and-sand. Sand may be preferable but be aware that your goldfish will disturb it regularly, so be sure your filtration system can handle silt.
Goldfish love to taste test and rearrange tank decorations, so whatever you choose, be sure it’s tough. Driftwood is a great start (if only for aesthetic reasons) and live plants are excellent. The best live plants for goldfish include java fern https://livefish.com.au/crested-java-fern and anubias https://livefish.com.au/anubias-large-assorted. You will need to make sure they are well anchored to avoid tipping.
Goldfish are considered a cold-water species and will do best in temperatures between 19-23 C (66.2-73.4 F). You should keep your aquarium out of direct sunlight and perhaps consider some insulation or even a water-cooling system. However, they are not particularly susceptible to temperature changes , so a water heater is not necessary even in cooler indoor climates.
Your Ph should be 6.5 – 7.5 and you should aim for a hardness of 5 - 15 DGH. To ensure your pH and hardness are suitable you should invest in a testing kit https://livefish.com.au/accessories/test-kits-water-quality. Always ensure your water is properly filtered, and regularly change the water (25% weekly or 50% every other week).
You should also filter the substrate https://livefish.com.au/accessories/gravel-and-sand regularly and adjust the chemistry of any tap water you use to top your tank. You may do this with one of our many water conditioning products https://livefish.com.au/accessories/water-conditioners.
Goldfish are also a popular choice for outdoor ponds.
Feeding and Care
Goldfish are voracious feeders and will eat as much as you give them, often to the point of illness. The amount and frequency of feeding depend not only on the age of your fish but the water temperature as well. In temperatures nearing the top of the recommended range, you should feed your fish 2 to 3 times a day, and only once or twice a day in cooler water. Flakes https://livefish.com.au/accessories/food/shop-by-fish/goldfish-and-koi-food are the usual go-to for goldfish and are a great staple, but should also be supplemented with meats like bloodworms or mosquito larvae and vegies like frozen peas. Only ever feed them enough for them to finish the meal within a couple of minutes in each feeding. Floating pellets should be avoided as this may lead to excessive air intake when gulping pellets at the surface. Check out our range of fish foods to find something suitable for your goldfish.
Great reasons to keep Goldfish in your tropical fish tank
- They are very forgiving of the usual mistakes that novice aquarists are prone to.
- They are intelligent and interactive with their owners.
- They are long-living and should offer years of companionship.
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