Celestial pearl danio Danio margaritatus

The tank column is the rarest thing on this page: every source that gives a volume gives the same one. Ten gallons, three times over, and Seriously Fish states dimensions instead, a base of 45 by 30 cm, which comes to about the same tank. On a site where the same row has run to a factor of three between sources, unanimity is worth naming.

The temperature column meets in three degrees, 73 to 76 °F, which is the same width as our least killifish and axolotl records and sits comfortably inside the 75 to 76 the rest of this site shares. But the number is not the disagreement. The disagreement is whether the tank needs a heater at all, and it is two against one.

Aquarium Co-Op: they can be kept in unheated aquariums, as long as your home does not get colder than 68 degrees, since they prefer cooler conditions than typical tropical fish. Aquarium Store Depot goes further: they actually have an affinity for cool water, so their fish tank should ideally be unheated. Seriously Fish assumes the opposite and specifies the equipment for it, a 25 to 50W heater.

None of the three is wrong, and the reason is in the habitat rather than the tank. Wikipedia and Seriously Fish both place the fish in shallow ponds on the Salween basin plateau at about 1,040 meters above sea level, which is high enough that a room at 70 °F is not a cold room. Wikipedia adds the other end of the tolerance, that the species is tolerant of temperatures above 26 °C.

So the honest answer is a thermometer before a heater, and it puts this record fourth on a list. Our clown killifish, least killifish and axolotl records all carry a source that raises keeping the animal without one, for three different reasons: a range that runs down to 68, a native range as far north as North Carolina, and a salamander that wants 61 to 64 °F. This is the first of the four where two sources say the heater is the mistake.

The hardness row carries a small arithmetic problem worth pointing at. Modest Fish publishes general hardness as 5 to 10 degrees or 90 to 268 ppm, and those are not the same figure: 5 to 10 dGH is 89 to 179 ppm, and 268 ppm is 15 dGH, which happens to be Seriously Fish's ceiling rather than Modest Fish's. The row uses the degree figure, because that is the number the source measured and the ppm is the number it calculated. Aquarium Store Depot's 2 to 10 is dKH, carbonate hardness, which measures something else entirely and is the same trap our rabbit snail and common pleco records carry.

Three of our sources ask for six celestial pearl danios and one asks for twenty or more, and twenty is the largest school any source asks for on any fish record on this site. The next figure below it is our chili rasbora record's twelve.

The three that ask for six do not stop at six. Aquarium Co-Op asks for at least six of the same species and then strongly suggests buying 10 to 15, since they can be a bit timid. Aquarium Store Depot says no less than six or seven, and that they behave completely differently in a proper group of 8 to 10 or more. Modest Fish says at least a group of six. Read as a set, nobody actually recommends six; six is the floor below which every source objects.

Seriously Fish gives the mechanism that explains the spread: rival males spar on a regular basis, and in a bigger group the aggression is diluted and the fish are bolder and better colored. Aquarium Store Depot describes the same behavior without the euphemism: males constantly battle over females, which unfortunately results in injury or, in the worst cases, even death.

So the group figure is not about shoaling instinct, which is the usual reason a nano fish record asks for eight. It is about spreading out a fight. That makes the sex ratio part of the same instruction, and two sources give it: keep fewer males than females, and Modest Fish specifies more females than males outright.

This record prints six as the row and names the twenty, because six is what every source will accept and twenty is what one source wants. A keeper buying six males has satisfied the row and ignored the reason for it.

The other half of the tank is plants, and here all four sources that discuss the setup agree, which happens on almost no other row of this record. Aquarium Store Depot puts it as a flat requirement: keeping healthy, stress-free CPDs is not possible without plants, and gives the reasons, that plants provide hiding places, good snacks and space for breeding. Aquarium Co-Op calls them shy fish that are easy to stress and asks for dense planting with open swimming space. Modest Fish calls them a bit shy, nervous and jumpy in general. Seriously Fish agrees and names the plants: this timid species should ideally be kept in a heavily-planted set-up, preferably with a dark substrate, filled with fine wool mops, Taxiphyllum or other fine-leaved plant.

That last name is one we hold a record for. Taxiphyllum barbieri is our java moss record, and its published rows contain this fish completely: pH 6.0 to 7.5 against 6.6 to 7.5, and 59 to 86 °F against 73 to 76. A bare ten gallon tank meets the volume row and fails the fish, and the plant the strictest source names is one whose own record agrees with this one on every figure they share.

Food is the one row where the care is genuinely easy, with a single condition attached. Seriously Fish: the fish prefers small live and frozen fare such as Daphnia and Artemia, will accept dried food, but should not be fed these exclusively. Aquarium Co-Op names baby brine shrimp, frozen cyclops and daphnia, micro worms and crushed flakes. Modest Fish gives the longest list of live food: Daphnia, brine shrimp, krill, Moina, Grindal and white worms. Aquarium Store Depot types it as an omnivore and adds that the plants themselves make for good snacks. So flake as part of the food is fine and flake as the whole of it is the refusal, which is a softer version of the same condition our pea puffer record carries, where dried food is refused outright.

Start with the layer, because that is where the sources split three ways. Aquarium Co-Op puts celestial pearl danios in the middle of the tank. Aquarium Store Depot says midwater. Modest Fish says bottom tank levels. Seriously Fish and Wikipedia give no layer at all.

This record follows the two that agree, and the row names the third, because for a fish this small the layer decides the neighbors rather than the decor. Eight other records here carry the same mid water zone, and a keeper who reads bottom and buys accordingly will stock a tank around the wrong shelf.

Then read the pH column. Three of the five nano records on this site stop at exactly 7.0, and this one starts at 6.6, so it overlaps each of the three across four tenths of a point. The other two start at or above 6.8 and overlap it at the alkaline end instead. There is no pH value where all six of these fish are inside their published rows.

That four tenths of a point has a name, and it came from one of our own sources recommending a pairing. Aquarium Co-Op's clown killifish page names celestial pearl danios as a tank mate. Our clown killifish record runs pH 4.0 to 7.0 and this record runs 6.6 to 7.5, so the two overlap between 6.6 and 7.0 and nowhere else. On temperature they are comfortable, 73 to 76 inside 68 to 79.

The pairing is not refused, and no source we hold refuses it. It is a pairing with a condition attached, which is that the water has to sit in a narrow window that suits neither fish's middle. Our tank mates grid prints the overlap rather than a verdict, which is the correct output when a source recommends something our own rows only just permit.

Nothing else here is refused either, and that is worth stating plainly rather than leaving as an absence. None of our five sources names a species this fish should not live with. The aggression they all describe is between celestial pearl danios themselves, and the caution they all give is about stress and cover rather than about predators. On a one inch fish that is a slightly surprising result, and it is what the sources say.