Sold at three inches, and one source ends at five hundred gallons
The common pleco is the fish this site was built for. One of our sources publishes a 30 gallon minimum and another says move up to 180 or even 500, which is a factor of nearly seventeen on the only figure that decides whether you should buy it, and the animal in the shop is three inches long.
Every record here prints the span its sources share. On this one there is no span worth printing, so the record prints the 75 gallons three of the six start at and then prints both ends. Our redtail catfish record held the widest disagreement on this site until now, at 300 to 2,700 gallons, a factor of nine. This is worse.
The second thing is the name. Wikipedia states it plainly and no aquarium source we hold repeats it: although the name Hypostomus plecostomus is often used to refer to common plecostomus sold in aquarium shops, most are actually members of other genera than Hypostomus. The fish being sold is usually a Pterygoplichthys. Station 06 has what that changes.
And the third is what is missing. Not one of the six sources publishes a growth rate. For a fish whose whole problem is the gap between the size in the shop and the size in five years, that is the field a buyer needs most, and the record leaves it blank rather than guessing.
It is worth being clear about what kind of animal this is before the figures, because the trade names do their best to hide it. Fishkeeping World puts it in the family Loricariidae, the armored catfish, and Wikipedia lists the names it is sold under: suckermouth catfish, common pleco, algae sucker, algae eater, janitor fish and sweeper fish. Four of those six describe a job rather than a species, which is how a two foot catfish ends up bought as equipment.
Why this record was written now
- The gap
- Three thousand six hundred searches a month, no AI overview on the result page, and the best ranked competitor sitting at position fourteen. Two other rows tie it on volume and both are worse targets.
- What it changes
- The widest source disagreement on this site, a second longest animal at the top of its range, and the first record here to leave the growth rate blank on purpose.
- What it does not
- No answer on which species is in your tank, because Wikipedia says most are not this one and no care sheet we hold says which.
The tank, and the widest disagreement on this site
| Source | Minimum tank | Adult size | Temperature | pH | Hardness |
|---|---|---|---|---|---|
| Fishkeeping World | 30 gal | 20 to 24 in | 72 to 86 °F | 6.5 to 7.5 | 20 to 35 dGH |
| Aquarium Source | 75 to 80 gal | 24 in | 72 to 86 °F | 6.5 to 7.5 | Up to 25 dGH |
| Tankarium | 75 to 150 gal | 12 to 24 in | 72 to 86 °F | 6.5 to 7.5 | Up to 25 dGH |
| Aquarium Co-Op | 75 to 500 gal | nearly 2 feet | none | none | none |
| Aquarium Store Depot | 70 gal | 18 in | none | none | none |
| Wikipedia | none | 19.7 in wild, 15 kept | none | none | none |
| This record | 75 gal | 15 in kept, 24 wild | 72 to 86 °F | 6.5 to 7.5 | Up to 446 ppm |
Read the first column and the disagreement is not a matter of opinion. 30 gallons and 500 gallons are the same fish in the same column, and nothing on either page marks the figure as belonging to a different age. Three of the six start at 75, which is where the row goes, and the note carries both ends because a reader deciding whether to buy needs to know that the range exists.
What the two extremes are probably answering is two different questions. 30 gallons will hold the fish in the shop, which is three inches long and shy. 500 gallons is the figure for a fish that is nearly two feet long and has been alive for a decade. Only Aquarium Store Depot writes the transition down: the fish gets sold at 2 inches for a few dollars, and nobody mentions it will hit 18 inches and produce enough waste to crash a 55-gallon tank.
The other three columns are the opposite case and worth noting for that reason. Three sources publish the temperature identically at 72 to 86 °F and the pH identically at 6.5 to 7.5, which almost never happens on this site. The chemistry is not what goes wrong with this animal.
Fishkeeping World is the page to read twice. It publishes 72 to 86 °F and 73 to 82 on the same page, 6.5 to 7.5 and 7.0 to 8.0, and its hardness as 20 to 35 dGH in one place and 20 to 35 dkH in another. Carbonate hardness and general hardness are not the same measurement, so those two cannot both be right with the same numbers, and a 20 dGH floor would put this fish in water two other sources treat as its ceiling. It is the same unit trap our rabbit snail record carries, appearing twice on one page.
The common pleco diet, and the part of it that looks like furniture
The label on the tank at the shop says algae eater. Every source we hold says that is not the diet. Aquarium Source asks for a varied diet of vegetables and protein-based foods, naming blanched lettuce, zucchini and peas alongside bloodworms, small crustaceans, fly larvae and earthworms. Fishkeeping World gives algae, wood fiber and crustaceans, with spinach, zucchini, cucumbers, lettuce and shelled peas. Tankarium calls it a scavenging omnivore taking algae, wood and plant materials, decaying scraps and live prey.
So a tank with no algae in it does not starve a common pleco, and a tank with plenty does not feed one. The fish will eat, and if nothing is offered it will eat what is there. Two sources name live prey and decaying scraps in the same list as the vegetables.
The item that surprises people is the wood. Aquarium Source: driftwood is important, too, because these fish like to munch on driftwood for a source of fiber. Fishkeeping World names driftwood in the diet as well, and Tankarium lists wood and plant materials before it lists anything else.
That makes this the one algae eater on this site that eats part of the hardscape. Our otocinclus record and our siamese algae eater record are the other two, and neither asks for wood as food. On a common pleco the driftwood is not decoration and not a hiding place; it is a line item.
The feeding schedule the sources give is modest, which is worth saying against the tank figures: Tankarium asks for sinking algae wafers and spirulina pellets with fresh blanched vegetables, and protein a few times weekly. The expense on this fish is never the food.
The full record
| Field | Recorded | Where it comes from |
|---|---|---|
| Minimum tank | 75 gal | This is the row the record exists for. Fishkeeping World publishes a minimum of 30 gallons with 100 called ideal. Aquarium Source asks for 75 to 80 gallons at the very minimum for an adult and allows up to 30 for a juvenile. Tankarium asks for 75 to 150 gallons per catfish. Aquarium Co-Op says it should probably start in a 75-gallon tank and eventually move up to 180 or even 500 gallons. Aquarium Store Depot gives 70 gallons as the minimum for the closely related species sold under the same name. The row prints the 75 where three sources start, and the note carries both ends, because 30 to 500 gallons is a factor of nearly seventeen and station 02 has what that means. For comparison inside this site, our redtail catfish record runs 300 to 2,700 gallons across its sources, a factor of nine, and that was the widest disagreement here until this record. |
| Temperature | 72 to 86 °F | Three sources publish the identical band, which is unusual on this site: Aquarium Source 72 to 86 F, Tankarium 72 to 86, and Fishkeeping World 72 to 86 F, 22 to 30 C. Fishkeeping World also publishes 73 to 82 F on the same page, so the row prints the figure three sources agree on and names the second rather than narrowing on a page that contradicts itself. Aquarium Co-Op, Aquarium Store Depot and Wikipedia publish no temperature for this fish at all. The band is wide enough to contain the 75 to 76 °F every other record on this site shares, so this fish does not move it, and it ties our betta record for the widest published band on any animal here. |
| pH | 6.5 to 7.5 | The same shape as the temperature row. Aquarium Source gives a neutral pH balance between 6.5 and 7.5, Tankarium 6.5 to 7.5, Fishkeeping World 6.5 to 7.5, and Fishkeeping World also gives 7.0 to 8.0 on the same page. The row prints what three sources publish identically. Nothing here is a demand: two of the sources say in the same breath that the fish is not fussy, and the pH window matters less on this record than on any other, because the thing that goes wrong with a common pleco is never the chemistry. |
| Hardness | Up to 446 ppm (25 dGH) | Two sources agree and describe it the same way. Aquarium Source: up to 25 dGH. Tankarium: not sensitive, tolerates up to 25 dGH. Fishkeeping World publishes 20 to 35 dGH in one place and 20 to 35 dkH in another, which are two different measurements carrying the same numbers, and a floor of 20 dGH would put this fish in harder water than the two other sources treat as its ceiling. The row prints the figure the two sources that agree publish, converted. It is the same unit trap our rabbit snail and redtail catfish records carry, and here it appears twice on one page. |
| Adult size | 15 in in a tank, 24 in the wild | Six sources and two questions, how big it gets and how big it gets indoors. On the wild figure: Aquarium Source 24 inches, Fishkeeping World 20 to 24, Tankarium 12 to 24, and Wikipedia up to 50 cm, 19.7 inches, standard length. On the captive figure, four of them agree: Aquarium Source around 15 inches when fully grown, Fishkeeping World most fish in captivity stop growing when they reach 15 inches, Tankarium an average of 15, Wikipedia averages 15 inches, 38 cm, in captivity. Aquarium Store Depot is the outlier and it is blunt: the fish gets sold at 2 inches for a few dollars, and nobody mentions it will hit 18 inches and produce enough waste to crash a 55-gallon tank. At 24 inches this would be the second longest animal on this site after our redtail catfish record at 55; at the 15 inches four sources give for a tank it sits just under our flowerhorn and clown loach records at 16. |
| Diet | Omnivore, and it needs wood | The name on the tank at the shop is algae eater and every source we hold says that is not the diet. Aquarium Source asks for a varied diet of vegetables and protein-based foods, naming blanched lettuce, zucchini and peas alongside bloodworms, small crustaceans, fly larvae and earthworms, and adds that driftwood is important, too, because these fish like to munch on driftwood for a source of fiber. Fishkeeping World gives algae, wood fiber and crustaceans, with spinach, zucchini, cucumbers, lettuce and shelled peas, and driftwood. Tankarium calls it a scavenging omnivore taking algae, wood and plant materials, decaying scraps and live prey, and asks for sinking algae wafers and spirulina pellets with fresh blanched vegetables and protein a few times weekly. Wood is not decoration on this record, it is a food two sources name and a third implies, and it is the one thing our otocinclus and siamese algae eater records, the other two algae eaters here, do not ask for. |
| Water column | Bottom, and awake at night | Every source puts it on the floor and two say when it is up. Aquarium Source: bottom-dwellers. Fishkeeping World: plecos are naturally nocturnal, and it spends most of its time slowly swimming along the bottom. Tankarium: nocturnal and active at night, and it adds the shape of the temperament, that juveniles are shy and mellow while adults are often aggressive and territorial. Aquarium Source agrees and gives the specific target: a grown pleco can target brightly colored fish with flowing fins. That is what the two refusals under station 07 rest on, and it is a behavior nobody sees in the shop, because the fish in the shop is three inches long and shy. |
| Lifespan | 10 to 15 years | Aquarium Source gives between 10 and 15 years, Fishkeeping World 10 to 15 years in captivity, and Tankarium up to 15 years in your aquarium. Nobody publishes anything shorter. Fifteen years puts this fish in the longest commitment group on this site alongside our oscar record at 10 to 20 and our clown loach record at 10 to 30, and it is the figure that turns the tank row from a purchase into a decade. Aquarium Co-Op puts that plainly and it is the most useful sentence any of our sources writes about this animal: it strongly advises against getting monster fish unless you are prepared to keep them for their entire lives, because they are nearly impossible to rehome. |
| Growth rate | Can double in size in under 6 months | Tankarium is the only source of six with a rate: they can double their size in less than 6 months, against a full grown range of 15 to 24 in depending on species. Two more describe the same thing without a number. Aquarium Source calls it a pretty steady growth rate. Aquarium Store Depot says people buy them small, they grow fast, and by the time the fish is a foot long the owner surrenders it or moves it to a pond, and the 18 in figure on that page belongs to the sailfin rather than to this fish. Fishkeeping World and Wikipedia publish adult sizes species by species and no rate for any of them. |
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. On this one it is the tank, and the two figures are a factor of nearly seventeen apart.
Fishkeeping World, on the minimum
30 gallons
Aquarium Co-Op, on the same fish
should probably start in a 75-gallon tank and eventually move up to 180 or even 500 gallons
Aquarium Store Depot, on what happens in between
The common pleco gets sold at 2 inches for a few dollars, and nobody mentions it will hit 18 inches and produce enough waste to crash a 55-gallon tank
What we record: we print the 75 gallons three sources start at, and we print both ends. These two figures are not describing the same animal at the same age, which is the whole trouble: 30 gallons is a figure for the fish in the shop and 500 is a figure for the fish you will have in ten years, and only one of our six sources says out loud which one it is answering.
The row that would settle it is the row nobody publishes. Not one source we hold gives a growth rate, so the record leaves that field blank rather than guessing, and station 05 says what is missing.
What we will not do is average 30 and 500, because 265 gallons is a number no source states and no keeper can use.
The row nobody publishes, and it is the one this fish is about
This record leaves the growth rate blank. That is not an omission we are apologizing for; it is the finding. Not one of the six sources gives a rate, a time to full size, or an age at which the fish stops. Aquarium Co-Op comes closest and it is a sentence rather than a figure: this 3-inch baby eventually grows up to be a nearly 2-foot beast.
Consider what a buyer is actually deciding. Every source agrees the fish reaches around 15 inches indoors and lives 10 to 15 years. Three of them say start at 75 gallons. The question that follows is how long the 75 gallons lasts, and no page we hold answers it. A figure as ordinary as inches per year would turn this record from a warning into a plan.
The blank matters more here than on any other record on this site, and it is worth comparing with the blanks we carry elsewhere. Our water sprite record has no adult size because no aquarium source publishes one for a plant nobody measures. Our flowerhorn record has no species name because the animal is a hybrid with no wild population. Those are blanks about things that may not exist.
This one is a blank about a number that certainly exists and that anybody breeding or importing these fish knows. It is simply not written down anywhere we can cite, so the row stays empty and this station says why. The record would rather be visibly incomplete than quietly invent a rate.
What we can state from the sources is the endpoint and the term: 15 inches, 10 to 15 years, and Aquarium Co-Op’s reason for refusing the fish outright. They are nearly impossible to rehome.
Common pleco against bristlenose pleco, and the name that is probably wrong
| Field | Common pleco | Bristlenose pleco |
|---|---|---|
| Minimum tank | 75 gal | 20 gal |
| Adult size | 15 in in a tank | 4 to 6 in |
| Temperature | 72 to 86 °F | 74 to 79 °F |
| Lifespan | 10 to 15 years | 5 to 14 years |
| Wood in the diet | Named by two sources | Named by two sources |
| Grown temperament | Territorial and aggressive | Peaceful |
Two of our six sources do not just compare these fish, they choose. Aquarium Co-Op: bristlenose, rubber lip and clown plecos are all beautiful catfish that stay between 4 to 6 inches in length, and are better suited for the average home aquarium. Aquarium Store Depot is shorter about it: for 90 percent of setups, the bristlenose is the correct pleco.
Our own two records put a number on the difference. Bristlenose pleco, 20 gallons and 4 to 6 inches. Common pleco, 75 gallons at the start and up to 500 on one source. That is twenty five times the volume for the same job in the same tank, and the job is one both fish do.
Then there is the name, and this is where the record has to be careful about what it can claim. Wikipedia says most fish sold as common plecos are not Hypostomus at all but members of other genera, usually Pterygoplichthys, and adds that the confusion has followed the fish into the invasive species literature, where recorded populations turned out to be misidentified. Aquarium Store Depot names the problem from the retail side: the Trinidad pleco is closely related and is regularly sold under that name, reaching 12 inches and asking for 70 gallons.
Five of our six sources print Hypostomus plecostomus and stop. So the figures on this record are the figures published under a name that is probably not the fish in front of you, and the honest use of them is as an upper bound on a decision rather than a specification. A 12 inch Trinidad pleco and a 24 inch common pleco are both bad news in a 30 gallon tank, which is the only conclusion that survives the uncertainty.
| Sold as | Species named | Adult size | Tank | Who says so |
|---|---|---|---|---|
| Common pleco | Hypostomus plecostomus | 15 to 24 in | 75 gal and up | Five sources, all using the same name |
| Common pleco, in fact | Other genera, usually Pterygoplichthys | not stated | not stated | Wikipedia only |
| Trinidad pleco | Closely related, sold under the same name | 12 in | 70 gal | Aquarium Store Depot |
| Bristlenose pleco | A record of its own here | 4 to 6 in | 20 gal | Recommended instead by two sources |
| Rubber lip pleco | not named | 4 to 6 in | not stated | Aquarium Co-Op |
| Clown pleco | not named | 4 to 6 in | not stated | Aquarium Co-Op |
Read that table as a shopping problem rather than a taxonomy one. Four of the six rows are catfish that stay between four and six inches, and they are sold in the same freshwater aquarium shop, in the same size, at the same age, often on the same shelf. The one row with a 75 gallon floor and a 500 gallon ceiling is not distinguishable from the others when it is three inches long, and the label does not help, because Wikipedia says the label is usually wrong.
The practical instruction that follows is short. Ask which species it is, and if nobody knows, buy the one that is named. Our bristlenose pleco record exists because that is the answer two of these sources give unprompted.
This is also why care advice for plecos travels badly. A care sheet written for one of these armored catfish is not care advice for the others, and the figures that differ most between them are the two that decide whether a tank works: adult size and volume. Between the rows above, the published tank floor runs from 20 gallons to 500, and every one of those plecos is sold at two to three inches. A page that says plecos need such and such, without naming the species, is not saying anything a buyer can act on.
What a grown one does, and the two pairings this record refuses
The temperament changes and two sources say so. Tankarium: juveniles are shy and mellow, adults are often aggressive and territorial, and it recommends they are best kept on their own. Aquarium Source agrees and gives the specific target: a grown common pleco can target brightly colored fish with flowing fins.
That sentence is what the refusals rest on. Our betta record is the flowing-finned fish on this site, and it runs 72 to 86 °F, the identical band to this record, so there is no temperature that separates them. Our angelfish record runs 78 to 84 and overlaps this one across 78 to 82, and an angelfish is a tall trailing-finned cichlid feeding in open water. Both are refused on the record, printed under the pairings grid rather than resolved quietly.
The third pairing is the one people actually build, and it is a caution rather than a refusal. If two sources tell you to buy a bristlenose instead, the tank that results often has both. The water works, at 74 to 79 °F. What limits it is a published number: Fishkeeping World says to limit aggression between pleco fish by housing a maximum of two plecos in one tank.
So the pairing is exactly two fish and not the beginning of a collection, and one of the two will eventually need twenty five times the volume of the other. That asymmetry is the whole record in one line.
What no source we hold puts a number on is the waste. Aquarium Store Depot raises it as the reason the tank fails, saying the grown fish produces enough to crash a 55-gallon tank, and then gives no figure. It is the second thing this record cannot state, after the growth rate, and both gaps point the same way: the sources describe the outcome and not the rate at which it arrives.
Is it a community fish, then? At the size it is sold, yes, and every source that mentions the young fish calls it peaceful or shy. At the size it reaches, no source we hold recommends keeping it in a community tank of small fish, and two describe it as territorial. The species does not change temperament so much as the tank stops being able to hold the argument. A bottom dweller of fifteen inches in a four foot tank is the tank.
Plants are the other question a keeper asks, and the sources answer it only halfway. Tankarium lists wood and plant materials in the diet, and Fishkeeping World names spinach, cucumbers and shelled peas as food, which is the same tissue. Nobody publishes whether a common pleco will strip a planted freshwater aquarium. Our own plant records are the ones with the exposure: the six of them run from anubias, which two sources call tough enough for large fish, to water wisteria, whose own sources name goldfish and oscars as fish that uproot it. Neither names this one, so the record does not either.
Common pleco questions, answered from the record
How big does a common pleco get?
Around 15 inches in a tank, on four of our six sources: Aquarium Source, Fishkeeping World, Tankarium and Wikipedia all give 15 as the captive figure. Aquarium Store Depot says 18. In the wild three sources give 24 inches and Wikipedia gives 19.7 inches standard length. At 24 inches it would be the second longest animal on this site after our redtail catfish record.
What size tank does a common pleco need?
Our sources will not agree, and the range is the point. Fishkeeping World publishes a 30 gallon minimum. Aquarium Source asks 75 to 80 for an adult. Tankarium asks 75 to 150. Aquarium Co-Op says start at 75 and move up to 180 or even 500. This record prints the 75 where three of them start and names both ends, because 30 to 500 is a factor of nearly seventeen and it is the widest disagreement on this site.
How fast does a common pleco grow?
No source we hold publishes a rate. Not one of the six gives inches per month, a time to full size, or an age at which growth stops. The row on this record is deliberately blank. Aquarium Co-Op comes closest with a sentence rather than a figure: this 3-inch baby eventually grows up to be a nearly 2-foot beast. Station 05 says why we leave it empty rather than estimating.
Is my common pleco actually a common pleco?
Probably not, and Wikipedia is the source that says so: although the name Hypostomus plecostomus is often used to refer to common plecostomus sold in aquarium shops, most are actually members of other genera than Hypostomus. The fish sold are usually Pterygoplichthys. Aquarium Store Depot adds that the Trinidad pleco is regularly sold under the same name and reaches 12 inches. Five of our six sources print the binomial without the caveat.
What do common plecos eat?
Not algae alone. Aquarium Source asks for vegetables and protein: blanched lettuce, zucchini and peas with bloodworms, small crustaceans, fly larvae and earthworms. Fishkeeping World gives algae, wood fiber and crustaceans plus spinach, cucumbers and shelled peas. Tankarium calls it a scavenging omnivore that also takes decaying scraps and live prey. Two sources name driftwood as food, for fiber, which no other algae eater on this site asks for.
Does a common pleco need driftwood?
Two sources say yes and give the reason. Aquarium Source: driftwood is important, too, because these fish like to munch on driftwood for a source of fiber. Fishkeeping World names wood fiber and driftwood in the diet. On this record the wood is a line item rather than decoration, which separates it from our otocinclus and siamese algae eater records.
How long do common plecos live?
10 to 15 years. Aquarium Source gives between 10 and 15, Fishkeeping World 10 to 15 in captivity, and Tankarium up to 15 in your aquarium. Nobody publishes anything shorter, which is why Aquarium Co-Op frames the purchase the way it does: it strongly advises against monster fish unless you are prepared to keep them for their entire lives, because they are nearly impossible to rehome.
Should I get a common pleco or a bristlenose pleco?
Two of our sources answer this without being asked. Aquarium Co-Op recommends bristlenose, rubber lip and clown plecos, which stay 4 to 6 inches and are better suited for the average home aquarium. Aquarium Store Depot: for 90 percent of setups, the bristlenose is the correct pleco. Our bristlenose record is 20 gallons and 4 to 6 inches against 75 gallons and 15 inches here, which is twenty five times the volume for the same job.
Can I keep two plecos together?
Two is the published limit. Fishkeeping World says to limit aggression between pleco fish by housing a maximum of two plecos in one tank, and Tankarium says they often become aggressive with each other and are best kept on their own. A common pleco and a bristlenose share water at 74 to 79 °F, so that pairing is carried here as one setting only rather than as a refusal.
What temperature and pH does a common pleco need?
72 to 86 °F and pH 6.5 to 7.5, published identically by three of our sources, which is rare on this site. Fishkeeping World also prints 73 to 82 °F and 7.0 to 8.0 on the same page, so the record prints what three sources agree on and names the second figures. The chemistry is the easy part of this fish.
Which fish should not live with a common pleco?
Aquarium Source records that a grown one can target brightly colored fish with flowing fins, and Tankarium says adults are often aggressive and territorial where juveniles are shy. This record refuses two pairings on that basis: our betta record, which shares the identical 72 to 86 °F band, and our angelfish record, which overlaps it across 78 to 82.
Are common plecos invasive?
Yes, and two sources raise it. Wikipedia records the species as invasive in Bangladesh, India, Malaysia, Indonesia and Sri Lanka, while noting that many populations recorded as this species were misidentified. Aquarium Source attributes it to pet owners releasing the fish. Aquarium Co-Op is direct: do not release your common pleco into the wild because they are a highly invasive species. Given that they are also nearly impossible to rehome, the decision is the one made at the shop.
What a common pleco needs that a bristlenose does not
Three of these are about volume and one of them is food that looks like furniture.
- A tank you have not bought yet75 gallons is where three sources start and one of them says move up to 180 or even 500, so the honest kit item is the second tank rather than the first
- Driftwood, as a foodtwo sources name wood in the diet and one gives the reason, fiber, so this is the one algae eater on this site that eats part of the hardscape
- Filtration sized for the waste, not the waterone source raises output rather than volume, saying the grown fish produces enough waste to crash a 55-gallon tank, and no source we hold puts a number on it
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
Aquarium Co-Op, care guide for plecostomus, Aquarium Source, common pleco, Fishkeeping World, plecostomus, Tankarium, pleco fish, Aquarium Store Depot, types of plecos and Wikipedia, Hypostomus plecostomus
- Conflicts
Printed rather than resolved: one source asks for 30 gallons and another for up to 500, and one page publishes two temperature bands, two pH ranges and two hardness units.
- Not recorded
A growth rate, because not one of the six sources publishes one, and on this fish that is the field that matters most; the species actually in the tank, because Wikipedia says most fish sold under this name are not in this genus and no aquarium source we hold repeats that; a figure for waste output, because the one source that raises it gives a consequence rather than a number; and whether the fish that stops at 15 inches indoors is the same fish that reaches 24 in a river, or a different animal held small