The record where the sources argue about the tank
Every other record on this site starts from a water figure that its sources broadly agree on. Goldfish care does not have one of those, because the loudest question in the hobby is how many gallons this fish needs, and our six sources answer it with 10, 20, 40, and a shrug.
That is not a reason to skip the question. It is the reason this record exists in the form it does. Five of our sources publish a gallon floor per fish and they do not match each other: Aqueon and Wikipedia both say 20 gallons for a common, comet or shubunkin and about 10 for a smaller fancy, the Chicago Exotics Animal Hospital doubles both figures, and PetMD stretches the top end to 50 or 100 gallons for the largest varieties. The sixth, Aquarium Science, opens its stocking page with the sentence that explains the other five: stocking for goldfish is controversial.
So the record carries a figure and prints the spread that produced it. What it does not do is pretend the sources agree somewhere else instead: four of them treat this fish as an unusually heavy waste load and size the filter upward for it, and the fifth lists exactly that comparison among the claims it rejects. The narrow thing all six leave standing is that water quality cannot be traded for gallons, and station 05 sets out who says what.
If you came here for a single number, the record carries 20 gallons and the reason is on the row. If you came here to decide something, read station 05 instead of station 03.
Why this record was written now
- The gap
- It was first in the freshwater fish queue, and it is the most searched species this site did not hold. Nothing here answered how long goldfish live, how big they get, or whether they need a heater.
- What it changes
- The silo gains its first coldwater fish and its first fish with a temperature ceiling below every other record. It also gains a fish that eats live plants, which no record here had.
- What it does not
- Two fields stay blank. No source states a hardness figure, and the only source that states a group size states it in order to reject it. Neither blank has been filled with a number that looked reasonable.
Two different fish, one shop label
Nearly every figure on this record splits before it can be recorded, and it splits the same way in three independent sources. On one side the long bodied single tails: the common goldfish, the comet, the shubunkin. On the other the short bodied fancies: the fantail, the oranda, the ryukin, the ranchu. Aqueon splits its tank size and its temperature by that line. The Chicago Exotics Animal Hospital splits its tank size by it. Wikipedia splits its tank size by it and adds that temperatures under about 50 °F are dangerous to the fancy varieties specifically.
| Field | Long bodied single tails | Short bodied fancies | Who splits it |
|---|---|---|---|
| Sold as | Common, comet, shubunkin | Fantail, oranda, ryukin, ranchu | Aqueon, Wikipedia |
| Gallons per fish | 20 | 10 | Aqueon, Wikipedia |
| Gallons per fish | 40 | 20 | Chicago Exotics Animal Hospital |
| Each extra fish | 20 gal | 15 gal | Chicago Exotics Animal Hospital |
| Temperature | 60 to 70 °F | 68 to 74 °F | Aqueon |
| Cold limit | Not stated | Below about 50 °F is dangerous | Wikipedia |
| Outdoors | Suited to ponds | More vulnerable to predators, needs winter protection | Aqueon |
| Kept together | May become too boisterous as they grow | May need to be separated from the single tails | Aqueon |
The last row is the one that gets missed. Aqueon does not only split the care figures, it states that commons, comets and shubunkins may become too boisterous for smaller fancy goldfish as they grow and may need to be separated. The two halves of this record are a tank mate question with each other.
Read the two temperature cells together, because they are the reason this record has the strangest number on the site. Aqueon's ceiling for the single tails, 70 °F, sits below the floor PetMD gives for goldfish generally, 72 °F. Taken at their word, the two halves of the same species cannot share a heater setting. Station 03 draws that.
Five sources, five bands, one degree
Each tube below is one source's published temperature range, drawn on the same scale. The bright line is at 72 °F, and it is there because 72 is the only degree that falls inside every band except one. This is not our figure. It is what five published ranges have left over once you lay them on top of each other.
Given as the optimum temperature for fancy goldfish.
Called an ideal temperature, with a floor of 65 for strong growth and stress above 80.
Given as the optimum, with over 86 °F harmful and under about 50 dangerous to the fancies.
The veterinary band, and the only one that adds they are more tolerant of cooler water than warmer.
Given as most comfortable around room temperature, and the only band whose floor is the shared degree.
The band that breaks the arithmetic: its ceiling is two degrees below the shared line.
- What the record carries. 68 to 74 °F, because two independent sources publish exactly that band and no other band appears twice.
- What the overlap says. Take the five bands drawn for goldfish generally or for fancies and the shared range is 72 to 72. One degree, from five published ranges, which is the same shape of finding as the hardness ranges on our kuhli loach record, where two sources meet at a single point.
- What the sixth band does to it. Add Aqueon's 60 to 70 for commons and comets and there is no shared degree at all. Two fish sold from neighboring tanks under one name cannot be given one temperature by their own sources.
- Where the ceiling sits against the rest of this site. 74 °F is the lowest ceiling on any record here. Our kuhli loach will not go below 74, so those two records share exactly one degree, and the stocking calculator now says so when you put them in the same tank.
- Do not read the cold end as an instruction. The Goldfish Tank drops the temperature to about 54 °F as a deliberate winter to induce spawning, then raises it to 68 to 74 to trigger it. That is a breeding protocol, not a care range.
The full record
| Field | Recorded | Where it comes from |
|---|---|---|
| Minimum tank | 20 gal | Chicago Exotics Animal Hospital: 20 gallons is the minimum acceptable tank size for short bodied varieties, with 15 gallons per additional goldfish, and 40 gallons per long bodied goldfish with an additional 20 gallons for each after that. Aqueon and Wikipedia both halve the first figure and both publish the same pair: 20 US gallons per fish for commons, comets and shubunkins, about 10 for the smaller fancies. PetMD gives about 20 gallons per fish and up to 50 to 100 for the largest varieties. Aquarium Science calls the question controversial. This record carries the highest floor any source gives for the smallest variety, which is 20. |
| Temperature | 68 to 74 °F | Aqueon, for fancy goldfish, and The Goldfish Tank both publish exactly 68 to 74. Three more bands are on this record and no two of them match: Chicago Exotics prefers 65 to 72, PetMD says goldfish are most comfortable around room temperature at 72 to 76, and Wikipedia gives an optimum of 68 to 72. Those five bands overlap at exactly one degree, 72. Aqueon's separate band for commons, comets and shubunkins, 60 to 70, does not contain that degree at all. |
| pH | 7.0 to 8.4 | Aqueon, which adds that pH is not critical but ideally should be between 7.0 and 8.4, and PetMD publishes the same band. Chicago Exotics prefers a much narrower 7.2 to 7.6, and The Goldfish Tank gives a single figure rather than a band: the ideal pH for goldfish is 7.4, and below 6.5 the nitrogen cycle begins to have difficulties. Every source here puts the floor at or above neutral, which is true of only two other records on this site. |
| Hardness | Not recorded yet | Blank, and for once a source argues for the blank rather than simply omitting it. Chicago Exotics states that goldfish do not seem to be preferential to a particular water hardness so long as it remains stable, which is a position and not a figure. The Goldfish Tank publishes no GH target either and says there is not a strict ideal for KH, though readings above 200 might indicate a pH at the higher end of the scale. Aqueon, PetMD, Wikipedia and Aquarium Science state nothing at all. |
| Adult size | 4 to 12 in | The span across three sources, and they are measuring different fish. Chicago Exotics says they grow up to 12 inches. Aquarium Science says a common goldfish in a small aquarium will grow to possibly four inches and no greater, that in a large lake it will normally grow to six inches with an occasional fish getting to eight, and cites USGS for wild fish at 12 to 22 centimeters, or 4.7 to 8.7 inches standard length. Wikipedia records the largest goldfish believed by the BBC to measure 19 inches, and a 15 inch fish weighing 9 pounds taken from a lake. |
| Diet | Omnivore, live plants included | Wikipedia: a wild diet of crustaceans, insects and various plant matter, opportunistic feeders that do not stop eating on their own accord, and the warning that because goldfish eat live plants their presence in a planted aquarium can be problematic. On how much and how often, our sources use three different units and disagree in all of them. Aqueon: only what they can consume in 2 to 3 minutes, once or twice a day. PetMD: adults once a day, on food providing about 30 percent protein, a figure Chicago Exotics repeats. Aquarium Science: greater than 45 percent protein, and the ration measured as 1 or 2 percent of body weight per day. |
| Water column | All levels | Ours, and the first record here that does not fit one of the four layers this site records. Wikipedia describes fish swimming to the front of the glass and going to the surface mouthing for food, a wild diet of crustaceans, insects and plant matter, and a fish that eats live plants, which is the whole tank rather than a layer. No source we read places this species in one. |
| Lifespan | 5 to 30 years | Chicago Exotics, which adds that the oldest ever recorded was 43. Every other figure sits inside that band and none of them agrees with another: PetMD says 10 to 15 years and sometimes up to 20, Aqueon says goldfish can live over 20 years in captivity, Wikipedia says beyond 10. Aquarium Science adds the detail that changes how the number reads: the nine longest lived goldfish in the world were all small commons of three and a half to four inches, three of them over forty. |
| Growth rate | Six inches in three to five months, if fed heavily | Aquarium Science, which also gives the other end of the same curve: the same fish fed 3 percent of its weight per day takes two to three years to reach slightly less than six inches. It is the only growth figure any of our six sources publishes, and it is a feeding curve rather than an age curve. |
The same nine fields for every animal on this site are in the A to Z index.
Where our sources disagree
Every record here names a disagreement. This one names the loudest argument in the hobby, and the useful part is not who wins it: five sources publish a gallon figure and the sixth calls the question controversial, then rejects the filtration claim the other five rely on and puts the whole weight on water quality instead.
The five sources that publish a floor
20 US gallons per fish for commons, comets and shubunkins, about 10 for the smaller fancies (Aqueon, Wikipedia). 20 gallons minimum for short bodied varieties with 15 per additional fish, 40 gallons per long bodied fish with 20 per additional (Chicago Exotics Animal Hospital). About 20 gallons per fish, up to 50 to 100 for the largest varieties (PetMD).
Aquarium Science
Stocking for goldfish is controversial. The nine longest lived goldfish in the world were all in small five to ten gallon aquariums. It lists among the claims it rejects the 30 to 100 gallon rules, the four to eight foot minimum tank length, the group of at least three, the idea that goldfish need cold water to thrive, and the claim that a small tank stops the body growing while the organs carry on, and the claim that goldfish must have much more filtration and many more water changes than other fish. Its own position is that water volume does not directly influence health, provided the fish can swim enough to prevent muscle atrophy, and that water quality does.
What we record: we carry the highest published floor for the smallest variety, 20 gallons, and print the argument rather than settling it. The one thing neither side trades away is water quality.
Wikipedia states this fish produces a large amount of waste both in its feces and through its gills and has high oxygen needs; Aqueon asks for a slightly over-sized filter and additional aeration at warmer temperatures; PetMD asks for five turnovers an hour. Aquarium Science lists the claim that goldfish need much more filtration than other fish among the claims it rejects, and still asks for adequate biofiltration and aeration, on the grounds that water volume does not directly influence health and water quality does.
A reader who takes the filtration seriously and the gallon figure loosely is closer to all six sources than a reader who does it the other way round.
What the argument in station 03 is actually about: water quality, not gallons
It is tempting to write that every source agrees about filtration even though they fight about tank size. They do not agree, and the disagreement is worth reading exactly, because the source that rejects the gallon rules rejects a filtration claim in the same breath and then puts the whole weight of the argument on water quality.
- Aqueon. The filter should be slightly over-sized to accommodate high waste production, and additional aeration is recommended when goldfish are kept at warmer temperatures. It states relatively high oxygen demands, a fish that grows quite large, and a significant amount of waste. Change 10 percent of the water weekly or 25 percent every two weeks.
- Wikipedia. Goldfish produce a large amount of waste both in their feces and through their gills, releasing harmful chemicals into the water, and buildup of this waste to toxic levels can occur in a relatively short period of time. It records high oxygen needs and a requirement for a substantial volume of well filtered water.
- PetMD. The only source here that puts a rating on the filter: select one rated to turn the tank over at least five times an hour, so a 20 gallon tank wants 100 gallons per hour or better.
- The Goldfish Tank. Ammonia at 0 ppm, no nitrite reading in a cycled tank, no more than 40 ppm of nitrate, and no longer than a week between water changes.
- Aquarium Science, and this is the one that breaks the pattern. It lists the claim that goldfish absolutely must have much more filtration and many more water changes than other fish among the claims it calls false. Its own position is that water volume does not have a direct influence on the health of a goldfish, provided the fish can swim around enough to prevent muscle atrophy, and that water quality does. What it asks for is adequate biofiltration and aeration rather than gallons.
Set those side by side and the shape of the disagreement changes. Four sources treat goldfish as an unusually heavy load and size the equipment upward for it. The fifth denies the comparison and denies that volume matters, and then asks for biofiltration and aeration. Nobody on this record argues that a goldfish tank needs less filtration than a tropical tank of the same size, and nobody argues that water quality can be traded for gallons. That is the narrow thing all six sources leave standing, and it is narrower than the confident version of this paragraph would have been.
One honest note about the source that disagrees: among the cases it offers against the gallon rules are two goldfish kept in a small unfiltered aquarium for 21 and 23 years, while its own requirement is adequate biofiltration. That tension is in the source, not in our reading of it, and we are printing it rather than choosing the half that suits the record.
The nitrate ceiling is worth carrying across the site. Our water and health topic already prints a disagreement about what a safe ammonia reading is, where one source accepts 0.25 ppm and the one on this record accepts nothing above zero. Both figures are published with their sources attached, which is the only honest way to hold two numbers that cannot both be a threshold.
Six claims one source calls myths
Goldfish tank size is the one figure on this record that every source states and no two of them state the same way, so it is worth reading the dissent at full length rather than in summary.
Aquarium Science is already cited elsewhere on this site, and on goldfish it takes a position that puts it against every other source here. It is worth printing carefully, because the page is a list of claims it rejects and reading it the wrong way round would invert the source. These are the claims it says are false, not the claims it makes.
The page calls the escalating gallon rules incorrect and answers with cases: two goldfish kept in a small unfiltered aquarium for 21 and 23 years, a four gallon aquarium with eleven goldfish, and the observation that the nine longest lived goldfish in the world were all in small five to ten gallon tanks. It quotes Meredith Clawson offering 10 to 20 gallons per fancy fish to a beginner who has the space and the money, as a general suggestion and a starting point rather than a floor.
Rejected as a swimming room rule nobody has measured. No other source on this record states a tank length at all, which is worth noticing: the length rule is common in the hobby and absent from five of our six sources.
Rejected. This is why the group field on this record is blank. Wikipedia describes goldfish as gregarious and schooling, and says very rarely does a goldfish harm another, the only real threat being competition for food, but a description of sociable behavior is not a number. The one source that states a number states it in order to argue against it.
Rejected, and this is the claim that makes the coldwater label on the shop tank misleading. Aqueon calls them cold water fish and then says they can also be kept in heated aquariums. The five published bands in station 03 all sit at or above 60 °F and four of the five have their floor at 65 or higher.
Rejected, and it is the reason station 05 is worded the way it is. Four other sources on this record do treat goldfish as an unusually heavy load: Aqueon asks for a slightly over-sized filter for high waste production, Wikipedia records a large amount of waste through the feces and the gills, PetMD asks for five turnovers an hour. This source denies the comparison with other fish while still asking for adequate biofiltration and aeration, and states that water quality influences health directly where water volume does not.
Rejected as a claim, while the size effect itself is not. The same source states plainly that in a small aquarium a common goldfish will grow to possibly four inches and no greater, against six inches in a large lake. The dwarfing is recorded on this site. The harm attributed to it is disputed, and no source we read publishes a measurement of it.
This record does not adopt that position and does not hide it. The method page says what we do when sources disagree, and this is the clearest case of it on the site: the tank figure stays at the highest published floor for the smallest variety, and the argument against it is printed at full length rather than summarized into agreement.
Goldfish food, measured in three different units
Ask how much to feed a goldfish and our sources will answer in minutes, in meals per day, in percent protein and in percent of body weight. None of those units converts into another, and two of them disagree on the same axis, so the table prints all four rather than picking one.
| Source | How much | How often | Protein |
|---|---|---|---|
| Aqueon | Only what they can eat in 2 to 3 minutes | Once or twice a day | Not stated |
| PetMD | Not stated | Adults once a day, younger fish more often | About 30% |
| Chicago Exotics | Not stated | Not stated | About 30% |
| Aquarium Science | 1 to 2% of body weight a day for adults | Juveniles fed often can eat 15%, most eat 3 to 4% | Greater than 45% |
| Wikipedia | Opportunistic feeders that do not stop eating on their own accord | Not stated | Not stated |
- The protein figures are a real conflict, not a rounding. 30% and greater than 45% are different foods, and both are published as the right one. No source here explains the gap, and nothing on this record resolves it.
- The two minute rule and the body weight rule are not the same instruction. Aquarium Science works an example: two small three inch goldfish weighing about ten grams together should get roughly 0.2 to 0.4 grams of food a day. Most keepers offering food for two to three minutes are not offering a fifth of a gram.
- Wikipedia's sentence is the one that matters at the tank. A fish that does not stop eating on its own accord will not tell you when the ration was right, which is why every figure above is stated by the source as an amount to give rather than an amount the fish will accept.
- Live plants are food here. Wikipedia states that because goldfish eat live plants, their presence in a planted aquarium can be problematic. That is a diet fact rather than a warning about behavior, and it is the reason this record does not appear in our plant pairings.
How big they get and how long they live, which turn out to be one question
These are the two most searched goldfish questions and they have the same answer in our sources: it depends on the water the fish was in, and every figure published is a figure about a particular tank rather than about the species.
| Figure | Value | Measured where | Source |
|---|---|---|---|
| Adult length | Up to 12 in | Not stated | Chicago Exotics |
| Adult length | 4 in and no greater | A small aquarium | Aquarium Science |
| Adult length | 6 in, occasionally 8 | A large lake | Aquarium Science |
| Adult length | 7 in after five years | A 200 gallon aquarium | Aquarium Science |
| Adult length | 4.7 to 8.7 in | Wild fish, standard length, citing USGS | Aquarium Science |
| Largest recorded | 19 in | Believed by the BBC as of 2008 | Wikipedia |
| Heaviest recorded | 15 in, 9 lb | A 16 acre lake | Wikipedia |
| Lifespan | 5 to 30 years | Oldest ever recorded 43 | Chicago Exotics |
| Lifespan | 10 to 15 years, up to 20 | Kept in excellent conditions | PetMD |
| Lifespan | Over 20 years | In captivity | Aqueon |
| Lifespan | Beyond 10 years | In captivity | Wikipedia |
| Growth | 6 in in 3 to 5 months | A large tank, fed heavily | Aquarium Science |
| Growth | 6 in in 2 to 3 years | The same fish fed 3% of its weight a day | Aquarium Science |
Two things follow from reading the middle column. The first is that a 12 inch goldfish and a 4 inch goldfish can be the same animal, so any tank size argument built on the 12 inch figure is arguing about a fish that a small tank will not produce. The second is that the growth figures are feeding curves rather than age curves: the same fish reaches six inches in four months or in three years depending only on the ration.
The lifespan column has a detail the other rows do not. Aquarium Science states that the nine longest lived goldfish in the world were all small commons of three and a half to four inches, three of them over forty. Whatever that says about tank size, it says clearly that the small ones are not the short lived ones.
For comparison against the rest of the site: the only other record here whose lifespan runs past twenty years is the corydoras, and 5 to 30 is the widest lifespan band we carry. The otocinclus record is still the one where four sources publish no lifespan at all.
The blank a source argued for
Hardness
Most blank fields on this site exist because nobody published a figure. The hardness row on this record is different: a veterinary source published a reason not to.
The Chicago Exotics Animal Hospital states that goldfish do not seem to be preferential to a particular water hardness, so long as it remains stable. The Goldfish Tank publishes no GH target either, and says there is not a strict ideal for KH, though readings above 200 might indicate that pH is at the higher end of the scale. Aqueon, PetMD, Wikipedia and Aquarium Science state nothing at all.
So the field stays empty and the reason is stored with it. A number here would have to come from a general aquarium article rather than from a goldfish source, and this record would then carry a figure its own sources never printed.
What that leaves on the record
Eight of the nine rows carry a figure and one carries a stated position instead. Reading the pH row next to it is instructive: every source here puts the pH floor at or above neutral, from Aqueon's 7.0 to 8.4 to a single ideal of 7.4 at The Goldfish Tank, which makes goldfish one of only three records on this site with an alkaline floor. The other two are the guppy and the nerite snail.
That matters more than the missing hardness number. A keeper moving a goldfish into a soft, acidic tank set up for our ember tetra at pH 5.5 to 7.0 is working against every pH figure on this page, and the hardness reading would not have told them so.
What this record will not answer
Four questions people ask about goldfish that our six sources do not settle, printed here so the gaps are visible rather than glossed.
- How many goldfish fit in a given tank. The floors published run from 10 to 40 gallons per fish and one source disputes the premise. This record carries 20 and the calculator uses that figure, which means the calculator is repeating a published floor rather than resolving the argument above it.
- How many to keep together. No number is carried, for the reason in station 06. If you want a figure from this site, our corydoras and ember tetra records carry group floors because their sources published them. This one does not.
- What hardness to aim for. Nothing, beyond stability. See station 09.
- What to do about a sick goldfish. The Chicago Exotics Animal Hospital names conditions, and this record transcribes the list without adding a treatment: proptosed eyes, bacterial and fungal disease, internal and external parasites, and dropsy, which it describes as huge volumes of air accumulating in the stomach associated with voracious surface gulping. The indicators it lists are swimming abnormalities, floating or sinking, appetite loss, color washout, ragged fins and lethargy. A fish showing those needs a veterinarian, not a care record.
Goldfish questions, answered from the record
How long do goldfish live?
Our sources publish four different answers and this record carries the widest of them, 5 to 30 years, from the Chicago Exotics Animal Hospital, which adds that the oldest ever recorded was 43. PetMD says 10 to 15 and sometimes up to 20 in excellent conditions. Aqueon says over 20 years in captivity. Wikipedia says beyond 10.
The figure worth carrying away is not the maximum but where it was reached: Aquarium Science states that the nine longest lived goldfish in the world were all small commons of three and a half to four inches, three of them over forty.
How big do goldfish get?
Between 4 and 12 inches, and which end you get is a fact about the tank rather than the fish. Aquarium Science states that a common goldfish in a small aquarium will grow to possibly four inches and no greater, six inches in a large lake with the occasional fish reaching eight, and about seven inches after five years in a 200 gallon aquarium. The Chicago Exotics Animal Hospital gives up to 12 inches. Wikipedia records a 19 inch fish as the largest believed at the time.
Station 08 prints all thirteen size and age figures on this record with what each one was measured in, because the numbers only make sense next to their conditions.
Do goldfish need a heater?
Our sources will not give you one answer, and the disagreement is more useful than an average would be. Aqueon calls them cold water fish and then says they can also be kept in heated aquariums, adding that a tank without a heater should hold only fish tolerant of cooler water. The Goldfish Tank recommends buying a heater if the water sits below 68 °F, and asks for above 65 °F to encourage strong growth. Aquarium Science lists the claim that goldfish need cold water to thrive among the claims it rejects.
What is not in dispute is the ceiling. The Goldfish Tank says a goldfish becomes very stressed above 80 °F, Wikipedia says over 86 °F can harm them, and the hotter the water the less oxygen it holds, which matters for a fish every source calls a heavy waste producer.
Can a goldfish live in a 10 gallon tank?
Two of our sources say a smaller fancy goldfish can, at about 10 gallons per fish: Aqueon and Wikipedia both publish that figure. A veterinary source disagrees and puts the same class of fish at 20 gallons minimum. This record carries 20, which is the highest published floor for the smallest variety.
Aquarium Science documents goldfish living long lives in far less than either figure and calls the whole question controversial. Station 06 prints its argument. What no source disputes is that a small tank needs more filtration and more frequent water changes, not fewer.
Can goldfish live in a bowl?
All three of our sources that mention it say no, with increasing force. PetMD states that small enclosures such as bowls limit the ability of a goldfish to thrive in captivity. Wikipedia states that fishbowls are detrimental to the health of goldfish and are prohibited by animal welfare legislation in several municipalities. Aqueon puts it as an instruction with an exclamation mark: goldfish should never be kept in bowls, small aquariums or any unfiltered container.
Read that next to station 05 and the reason is mechanical rather than moral. This is a fish our sources describe as producing a large amount of waste and having high oxygen needs, and a bowl is the one vessel with no filtration and the least surface movement.
How often should you feed a goldfish?
Aqueon says once or twice a day, and only what they can consume in 2 to 3 minutes. PetMD says adults once a day, with younger fish fed more often as they grow. Aquarium Science measures the ration instead of the clock: 1 to 2 percent of body weight a day for an adult, and it works an example where two three inch goldfish weighing about ten grams get 0.2 to 0.4 grams of food a day.
Wikipedia adds the sentence that makes all three necessary: goldfish are opportunistic feeders and do not stop eating on their own accord.
What should goldfish food contain?
Here our sources contradict each other outright. PetMD and the Chicago Exotics Animal Hospital both state that food should provide about 30 percent protein for a goldfish. Aquarium Science asks for greater than 45 percent. Neither figure is a range, and nothing in either source explains the other.
Both figures are printed in station 07 rather than averaged, because 30 and 45 percent are different foods and an average of them is a number no source published.
What are the types of goldfish?
Wikipedia records about 300 breeds recognized in China. Our sources do not describe them individually, and they all split the species the same way for care: long bodied single tails, which are the common goldfish, the comet and the shubunkin, and short bodied fancies, which include the fantail, the oranda, the ryukin and the ranchu.
The most searched of those names is the ranchu, and Wikipedia gives it its own article: a hooded variety of goldfish native to Japan which lacks a dorsal fin, developed from crossbreeding experiments with Chinese lionhead specimens, referred to as the king of goldfish by the Japanese people, and reaching between 6 and 8 inches when mature. That figure sits inside this record’s 4 to 12 inch range and is a useful reminder of what the range means: a mature fancy at 6 to 8 inches, not a 12 inch fish.
That split is the only variety distinction this record can carry, because it is the one the sources make. It changes the tank figure, the temperature band and, according to Aqueon, whether the fish is suited to an outdoor pond at all. Station 02 prints it as a table.
Can goldfish live with tropical fish?
Aqueon states that goldfish get along well with most peaceful, similarly sized fish and that fin nippers and boisterous fish should be avoided. Wikipedia adds that very rarely does a goldfish harm another goldfish, the only real threat being competition for food, so temperament is not usually the obstacle.
The pairing Aqueon does warn about is goldfish with goldfish: commons, comets and shubunkins may become too boisterous for smaller fancy goldfish as they grow and may need to be separated. Two fish sold from adjoining tanks under one name, and one source asking you to keep them apart.
Temperature is. This record's band tops out at 74 °F, the lowest ceiling on this site, and our kuhli loach will not go below 74. Those two records share exactly one degree. The tank mates grid prints every overlap on the site, and the calculator will tell you when a build has no single setting.
Do goldfish eat plants?
Yes, and Wikipedia states it as a diet fact rather than a warning: because goldfish eat live plants, their presence in a planted aquarium can be problematic. Its description of the wild diet is crustaceans, insects and various plant matter.
Our hornwort record is where this gets contested rather than settled. Aquarium Co-Op states there that plant eating animals such as goldfish, koi, African cichlids and turtles do not eat hornwort, and Aquarium Breeder states the opposite, to keep goldfish and herbivorous cichlids away from it because they can damage the plant.
Both are printed and neither is carried as a verdict. Our java fern record is the one that does settle it: four of its seven sources name goldfish among the animals that plant survives, and Aquarium Store Depot gives the mechanism, that java fern foliage contains chemicals that taste bad for plant-eating fish.
Our java moss record gives the third possible answer, which is that not one of its seven sources mentions goldfish at all, so that row is blank rather than reassuring. Everywhere else on this site a plant is something a species lives with; a goldfish tank is the one build where it is a consumable.
How many goldfish should be kept together?
This record carries no number, and the reason is that the only source stating one states it in order to reject it. Aquarium Science lists the claim that goldfish are social creatures needing groups of at least three among the claims it calls myths.
Wikipedia describes goldfish as gregarious, displaying schooling behavior. That is a description of the animal, not a floor for a keeper, and this site does not convert one into the other. Where our sources do publish a group floor we carry it, as on the corydoras and ember tetra records.
What water parameters does a goldfish tank need?
pH 7.0 to 8.4 from Aqueon and PetMD, narrowed to 7.2 to 7.6 by the Chicago Exotics Animal Hospital and given as a single ideal of 7.4 by The Goldfish Tank. Temperature 68 to 74 °F, the band two sources publish exactly. Hardness is blank, because a veterinary source states that stability matters and the value does not.
On the nitrogen side The Goldfish Tank gives ammonia at 0 ppm, no nitrite in a cycled tank, nitrate no higher than 40 ppm, and a water change at least weekly. Our water and health topic holds those figures against the other sources on this site, including one that accepts a small ammonia reading where this one accepts none.
Where does this record disagree with the rest of the site?
In three places, and all three are printed rather than smoothed. Its temperature ceiling of 74 °F is the third lowest here, behind the axolotl at 64 and the dojo loach at 72, and it narrows almost every mixed build. Its pH floor is alkaline, which only two other records share. And it eats live plants, which no other record here does.
The full index lists every record we hold, the freshwater fish silo lists what is still queued, and the method page explains what happens to a claim on this site when a new record contradicts it.
What a goldfish tank needs and a tropical tank does not
Three things every source on this record asks for, including the one that disputes the tank size.
- Filtration rated well above the tankPetMD: five turnovers an hour
- Water changes on a schedule, not on a smellno longer than a week
- Plants you can afford to loseWikipedia: they eat live plants
Every item our records ask for is gathered on the tank setup topic.
Nothing here is a paid link. It is the shortfall between what this record asks for and what a boxed kit contains.
How this record was compiled
- By
- Verified
- Sources
Aqueon, goldfish care guide, PetMD, how to take care of goldfish, Chicago Exotics Animal Hospital, Aquarium Science, goldfish, The Goldfish Tank, tank temperature and Wikipedia, Goldfish
- Conflicts
Printed above: five sources publish a gallon floor and a sixth calls the question controversial
- Blanks
Hardness stay empty until a source we trust states them
- Not recorded
Hardness, because a veterinary source says stability is the field that matters, and a group size, because the only source that states one states it in order to reject it