Freshwater fish

Of the records here, a betta in a heated five gallon asks the least of you: one fish, one decision, no group to get right. A school of ember tetras is close behind, and forgives a beginner more than corydoras does, because corydoras adds a substrate requirement on top of the group.

From these records: a betta at the surface, one group in mid water, one on the bottom and otocinclus grazing the surfaces. That is eight to ten ember tetras or a guppy trio in the middle, and six corydoras below. Not two groups in the same layer. The inch per gallon rule people quote is not in any source we use, and we do not print it.

Corydoras, kuhli loaches and the dojo loach, and all three need fine sand rather than gravel. All three also need a group: six or more of one species for the corydoras, five to six for the kuhli loach, and three or more for the dojo loach, whose sources put the figure anywhere from one to ten. The otocinclus works the same floor and is filed with the grazers rather than the bottom dwellers, because the source that describes its habits names both of those fish as its tank mates.

Take the overlap of every record in the tank, and check that it exists. Across all thirty species in this silo it does not, and nine records are why: the axolotl stops at 64 °F, the dojo loach at 72, the goldfish at 74, the angelfish does not start until 78, the flowerhorn not until 80, the german blue ram not until 84, the discus not until 85, and the clown loach record prints a single figure of 82 because that is the only temperature its five sources all allow.

Take those nine out and the other sixteen overlap from 75 to 76 °F, set at the bottom by the oscar and the siamese algae eater and at the top, alone, by our redtail catfish record, which stops at 76. That band was 75 to 79 until the platy record was written, because five records stop at 79 and nothing here stopped lower: the otocinclus, the kuhli loach, the bristlenose pleco, the african dwarf frog and the siamese algae eater.

Two of three sources on the platy record will not take that fish above 77 or 78, so the silo band lost two degrees to one record. The guppy is the widest range in the silo at 63 to 82, and the one where the setting inside that range changes how long the fish lives.

Yes for all but one record here, and unless your room holds a steady figure in the seventies overnight, which almost no room does. The exception is the dojo loach, where the most technical of our five sources says this is not a tropical species and should not be maintained as such for extended periods. On the guppy record the heater is more than a floor: its source states two to three years of life at 76 to 78 °F, eighteen months at 82, and over three and a half years at 72.

Four records state a minimum at or under five gallons and no two of them can share it. A school of eight to twelve chili rasboras is the one that puts the most animals in that volume. The betta at five to ten gallons, a pea puffer, which asks for five on its own and three more for each additional one, or an african dwarf frog, which asks for five per frog and wants a second frog. The corydoras and the ember tetra records both ask for ten and the kuhli loach asks for twenty. A five gallon has a short answer here, and it is a choice between two fish rather than a shortage of one.

For the betta, yes, and the source states it: one male, never two. Every other record here states a group. Six or more of one species for the corydoras, eight to ten ember tetras, five to six kuhli loaches as a minimum, six or more otocinclus, and for the guppy a ratio rather than a count: one male to two or three females. Keeping one of those is not a smaller version of the record.

There is no window left. Overlap all thirty records and the shared value is exactly 7.0: the guppy floor is 7.0 and the ember tetra and kuhli loach ceilings are 7.0. The individual ranges run from 3.5 on the loach to 8.5 on the guppy, so a tank of all six is a tank held at one number. Leave the guppy out and the window reopens to 6.5 to 7.0.

Smallest to largest: ember tetra 0.6 to 0.8 inches, chili rasbora 0.7 to 0.8, least killifish 0.6 male to 1.5 female, pea puffer 1, corydoras 1 to 3, clown killifish 1.4, otocinclus 1.4 to 2, honey gourami 1.6 to 2.2, siamese algae eater 3 to 6.3 depending which species you bought, guppy 2 to 2.5, betta 2.4 to 2.8, kuhli loach 3.5 to 3.9, angelfish 4 to 6 long and 6 to 8 tall, african dwarf frog 1 to 3, bristlenose pleco 4 to 6, goldfish 4 to 12, discus 5 to 7 across, axolotl 9 to 12, oscar 10 to 12, clown loach 6 to 13 in a tank and 16 on record, flowerhorn 9.5 to 16, common pleco 15 in a tank and 24 in the wild, and our redtail catfish record at 47 to 55, which is longer than the next two put together.

Two of those are not fish, and the silo says so on both records. The last five are the reason this silo needs a tank size column as well as a length, and the clown loach is the reason it needs the source beside the figure: two of its five sources say a captive fish stops at eight inches and two say thirteen.

A four inch bristlenose asks for twenty gallons and a four inch goldfish asks for twenty as well, while the angelfish at the same length asks for fifty five because it is measured the wrong way: it is 6 to 8 inches tall.

Three will, and no two of them eat the same algae. The otocinclus is specific about which: soft green algae and brown diatoms, not black beard algae and not green spot algae. The bristlenose pleco covers more of them, green algae, black hair algae, green slime algae and brown algae, and its source says of the black hair algae that it will keep it under control rather than get rid of it.

Both records also carry a source saying algae alone will not feed the fish. The siamese algae eater is the third and it is the one bought for the algae the other two will not clear: all four of its sources name black beard algae, two of them name hair algae, and one of the four adds that a well fed adult is less likely to graze at all.

Nothing else here eats algae: the corydoras record says so outright, the betta and the pea puffer are carnivores, the ember tetra takes tiny omnivore foods and the kuhli loach is a micropredator.

Because the sources we name do not state them. Lifespan used to be unverified for every species in this silo except the guppy, whose source gives two to three years and then moves the figure with the heater. Every record here carries one now except the otocinclus, each from a source named on its own record. The otocinclus does not, and it is blank against four sources: not one of them states a figure for a fish that mostly dies in its first month of starvation rather than of age. We would still rather show you an empty field than a number that came from nowhere.