Goldfish
Contributed by Altum and NetMax
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Contents:
This FAQ assumes you know a bit about basic fishkeeping and addresses some of the specifics of keeping goldfish. If you're completely new to fishkeeping, please read the beginner FAQ at theKrib.com first. Be sure you understand how to dechlorinate water, test for ammonia, and cycle a tank before you purchase your first goldfish.
There are two main kinds of goldfish in pet stores with somewhat different requirements. Pond goldfish, comets, and shubunkins have the shape of wild carp: long and slender with one tail. Goldfish are also bred with egg-shaped bodies and two tails. Some examples are orandas, lionheads, ryukins, and moors. For this article, we'll call the single tailed, slender fish comets and the fat, twin-tailed fish fancy goldfish or fancies.
Goldfish grow larger than you might think. Most goldfish sold in pet stores are babies. Small "feeder goldfish" are usually about three months old. Adult comets typically reach 8" (20 cm), although they can grow as large as a foot (30 cm). Fancy goldfish commonly reach 6" (15 cm), and sometimes grow as large as 8" (20 cm).
There is a common myth that goldfish do not outgrow their surroundings. It is certainly possible to permanently stunt fish by keeping them in close quarters and filthy water, but is that how you want to keep your pet? Goldfish kept in properly filtered tanks with good water quality grow rapidly and their size is limited only by their genetic potential.
Q: How much water do goldfish need?
A good rule of thumb for goldfish is three gallons of water per inch of body length for fat, fancy goldfish and two gallons per inch for comets. This means most fish will eventually require 15-20 gallons (60-75 liters) of water each. However, a fifteen or twenty gallon tank will not provide adequate swimming space for an adult goldfish. For fancies, a 29 or 30 gallon (108 liter) tank is a minimum. For the more active comets, a four foot (120 cm) or larger tank is better. In ponds where there is more debris blown in, plan on at twice as much water per fish.
Q: What's wrong with keeping goldfish in bowls?
If you've read this far, the problem is obvious. Goldfish outgrow even the largest bowls. Bowls are also usually unfiltered with still water so the fish suffers from poor water quality and lack of oxygen. It is possible to house a baby goldfish in a two gallon bowl for a short period of time, but bowls are never suitable long-term homes for goldfish.
Q: How long do goldfish live?
Fifteen to twenty years is typical, although some individuals live much longer. If your goldfish only lived three or four years, it did not die of old age.
Q: What do I do if my goldfish has outgrown my tank?
Buy a bigger tank? Cheap, large tanks are often offered inexpensively at yard sales or places like Craig's list. If you have comets, you can dig a pond in the garden for your pet. If you can find a person in your town with a pond, they may have room for another fish. Sometimes fish stores will accept large, healthy goldfish. If that doesn't work, try advertising in places like Freecycle. Goldfish rescue organizations also come and go, so look for one in your area. Whatever you do, do not release your pet goldfish into the wild. Bright orange fish are easy targets for predators, and those that do manage to survive wreak havoc with local ecosystems.
Q: Why did the store tell me not to buy ten-cent feeders for pets? Are they trying to rip me off?
Nope. Feeder fish are raised in crowded conditions and often carry diseases. Most die within a few weeks of when you bring them home. Only buy goldfish from uncrowded tanks where every single fish is healthy.
Goldfish are not shy and need plenty of swimming room so you don't need a lot of decorations or plants. Live plants are helpful to maintain good water quality. Avoid sharp plastic plants or rocks with delicate bubble-eye or veil tailed goldfish. If you don't have rooted live plants, go easy on the gravel. Just put enough to cover the bottom so it's really easy to clean. Some goldfish keepers say it's best have a clean, bare-bottom tank for longfinned fish that like to rest on the bottom of the tank.
Q: What temperature is best for goldfish?
Goldfish are temperate fish so they can survive a wide range of temperatures. They overwinter in ice-covered ponds and can tolerate summer heat as long as the water is adequately oxygenated. Generally, temperatures that are comfortable for humans are comfortable for goldfish. For an indoor tank, a temperature range somewhere between 60-72F (16-22C) is ideal.
Q: What filtration is best for goldfish?
Goldfish are hearty eaters and produce a lot of waste. Plan on generous biofiltration. To help choose your filter, check out the filtration FAQ . Plan on doing a lot of water changes for goldfish. 25% a week is typical.
Q: Should I use salt?
Goldfish do not require salt in the water for long-term health. Many internet sites recommend salt, probably because it can counteract the effects of nitrite poisoning when goldfish are kept in bowls and tanks without adequate biological filtration. Goldfish are fairly salt-tolerant, so do consider using salt as a medicine if your fish becomes sick or has a parasitic infection.
Q: What pH do they like?
Goldfish can tolerate a very wide pH range, but they prefer hard water with a mildly alkaline pH, around 7.2-7.6. Many peole find that the water from their tap is within these parameters. If yours is soft, you can harden water and raise the pH gradually and very easily by putting crushed coral or oyster shells in your tank or filter.
Goldfish are omnivores so offer a wide variety of foods. Start with a high-quality staple food designed for goldfish. Sinking pellets or crumbles are best for fancies because some fish gulp air and float after meals when they eat at the surface. Vary the staple diet with blanched green leafy vegetables, peas, orange slices, and protein-rich foods like bloodworms, daphnia and brine shrimp.
Q: Why do my goldfish always seem hungry? How much am I supposed to feed?
Goldfish constantly browse for food, so they're always looking for the next handout. You'll see them nibbling at plants or digging around the substrate all day. Because of the browsing behavior, goldfish do best fed a couple of small meals daily. Overfeeding fouls the water and will shorten the lives of your fish. Feed only what they eat eagerly (typically 2-3 mouthfuls of food) and never more than they can consume in three minutes. If your fish are growing, you're giving them plenty of food.
Yes, but there are some things to keep in mind. Goldfish require a lot of oxygen so a warm goldfish tank must be stocked very lightly. Temperatures over 78F (26C) are not considered good for the long-term health of goldfish. Goldfish also tend to put out a lot of waste and ammonia so mixing delicate, ammonia-sensitive tropicals with too many goldfish can be a problem. Aggressive or fin-nipping tropicals are not suitable companions for goldfish.
Q: What fish can I mix with goldfish?
Fancy goldfish have trouble competing with faster fish for food and are easy targets for fin nipping. They do best kept alone, or perhaps with cool-water catfish like dojo loaches or hillstream loaches. Cool-water Corydoras species like Corydoras paleatus or Corydoras undulatus can work while goldfish are small, but very large goldfish may try to eat them.
Comets mix easily with other peaceful cool water fish like shiners (Notropis spp.) or rosy red minnows. If your tank stays above 65F, you can also keep subtropical fish like zebra danios or rosy barbs. Like most omnivores, goldfish sometimes catch and eat other fish so avoid adding bite-sized fish like white clouds or bluefin killies to a goldfish tank.
Q: Can I keep different kinds of goldfish in the same tank?
You can mix goldfish with similar feeding habits. Comets, shubunkins, and other single tailed fish mix well. Double tailed orandas, lionheads, and ryukins can be mixed together, but fast single-tailed fish will tend to beat them to the food. Very slow or visually impaired goldfish like celestials, moors, and bubble-eyes need to be kept by themselves or they will not have enough of a chance to feed.
Q: What plants can I keep with goldfish?
Goldfish like to eat plants and dig at their roots so only the sturdiest plants work in goldfish tanks. Success has been reported with tough, well-rooted plants like swordplants, jungle val, and java fern or anubias tied to rocks or driftwood. Hornwort and anacharis float so they usually do reasonably well, although goldfish may eat tender shoots. Stem plants are usually dislodged and tender plants like hygrophila eaten. Many goldfish relish duckweed so try growing some in a separate container for your fish.
Fancy Goldfish, due to extensive line breeding for appearances, are prone to difficulties keeping their balance or orientation, especially as they get older. This is due to the non-optimal location of their swim bladder (too low or far backward). Swimming problems may first appear shortly after a meal, as air trapped in the stomach causes the fish some difficulty. In all but the most extreme cases, the use of sinking pellets or pre-soaked food usually alleviates the symptoms. For fish that are extremely sensitive to air trapped in pelleted foods, some goldfish keepers make homemade gel foods.
In extreme cases, fish have been known to flip around and spend the remainder of their lives upside down. Fortunately, their quality of life appears unaffected. If the swimming problems are not triggered by meals and not helped by changes in diet, your fish may have a swim bladder infection. Swim bladder infections can sometimes be cured with antibiotic foods.
Q: Why is my goldfish bloated?
With normal fish, bloating is usually a sign of serious illnes. However, fancy goldfish tend to have problems with constipation because of the shape of their bodies. Constipated goldfish bloat, fail to defecate, and sometimes have trouble swimming. Constipation can be usually be remedied by feeding cooked peas squeezed out of their skin, daphnia (frozen is fine), or with a 15 minute soak in 1 tsp/gallon epsom salt. If your goldfish is prone to consipation, feed it peas regularly.
Q: My bubble-eye goldfish's bubble popped. What do I do?
Keep the water clean and hope for the best. Some people like to add PimaFix and MelaFix to help prevent infection and speed healing. The bubbles sometimes grow back, although the fish may be lopsided.
Young goldfish are difficult to sex. Breeders learn to tell subtle differences in male and female fish, but for most people the fish only look different at spawning time. Mature males get white spots or bumps, called breeding tubercles, on their gill covers and pectoral fins, and the females grow fat with eggs. (Beginners sometimes confuse the breeding tubercles with ich - breeding tubercles ONLY appear on the head and pectoral fins.) If you see a spawning run, you can tell the male because he's doing the chasing!
Q: How can I tell when my goldfish are breeding?
First, your females will fatten up and the males will show breeding tubercles. When the fish breed, the males chase the females in a wild run around the aquarium. The male tries to corner the female and squeeze out her eggs, fertilizing them at the same time. Sometimes the females are slightly injured in the process but they generally recover fine. You can add a bit of MelaFix if the females' fins are torn.
If a lot of fish breed at once, the milt from the males can foul the water. Change water and add some ammonia neutralizer if the tank suddenly gets foamy. Like most cyprinids, goldfish will eat their eggs and young so you must take precautions if you want to raise the fry. In ponds with a lot of vegetation for cover, babies often survive.
Q: Can different kinds of goldfish cross-breed?
All goldfish are the same species (Crassius auratus) and can cross-breed. Goldfish and koi do not interbreed.
This article was contributed to the FAQ in 2006 by members of the Google group, The Freshwater Aquarium.
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