What size tank do chili rasboras need?

Seriously Fish gives a minimum base of 45 × 30 cm (about 18 × 12 in) for Boraras brigittae and recommends a group of 8–10 or more.

Is there a fish-per-gallon rule?

Not one we can source. This checker uses each species' published minimum tank footprint and water ranges instead, which reflect how much the fish swims and how big it gets.

Can a betta live in a nano tank?

Seriously Fish lists a minimum base of 45 × 30 cm for Betta splendens, 22–30 °C water, and says one male is best kept alone (or as a pair).

Entry 08Stocking

Which nano fish fit your tank

No fish-per-gallon rule. Each species is checked against the minimum footprint and the water ranges in its Seriously Fish profile, so you see why a fish fits or doesn't.

Last updatedOct 19, 2026

Species11, read Oct 19, 2026

Seriously Fish profiles: size, minimum base and water ranges
Species	Max size (SL)	Minimum base	Temp	pH	GH	Group
Chili rasboraBoraras brigittae	20 mm	45 × 30 cm18 × 12 in	20–28 °C	4.0–7.0	1–10	8–10 or more
Dwarf rasboraBoraras maculatus	25 mm	45 × 30 cm18 × 12 in	20–28 °C	4.0–6.5	1–5	8–10 or more
Ember tetraHyphessobrycon amandae	20 mm	45 × 30 cm18 × 12 in	20–28 °C	5.0–7.0	1–10	8–10 or more
Celestial pearl danioDanio margaritatus	21 mm	45 × 30 cm18 × 12 in	20–26 °C	6.5–7.5	5–15	a group (no number given)
Pygmy coryCorydoras pygmaeus	30 mm	45 × 30 cm18 × 12 in	22–26 °C	6.4–7.4	0–8	6 or more
Clown killifishEpiplatys annulatus	35 mm	45 × 30 cm18 × 12 in	20–26 °C	4.0–7.0	1–8	8–10 or more
Sparkling gouramiTrichopsis pumila	40 mm	45 × 30 cm18 × 12 in	22–28 °C	5.0–7.5	1–12	a pair or small group
Endler's livebearerPoecilia wingei	25 mm	45 × 30 cm18 × 12 in	24–30 °C	7.0–8.5	15–35	a colony (species-only tank if breeding)
Betta (Siamese fighting fish)Betta splendens	70 mm	45 × 30 cm18 × 12 in	22–30 °C	6.0–8.0	1–15	one male (or a pair); best kept alone
Neon tetraParacheirodon innesi	30 mm	60 × 30 cm24 × 12 in	21–25 °C	4.0–7.5	1–12	8–10 or more
Lambchop rasboraTrigonostigma hengeli	30 mm	60 × 30 cm24 × 12 in	23–28 °C	5.0–7.5	1–10	8–10 or more

How the check works

Every figure in the table is from the species' own profile on Seriously Fish (Seriously Fish¹), linked from its name. Max size is standard length, snout to the base of the tail. The minimum base is the length and width of tank floor they give for the species, which is why a tall tank with a small footprint doesn't gain anything here. A species fits when your base is at least that size in both directions and, if you check water, your temperature, pH and GH all fall inside its ranges.

The group column is Seriously Fish's recommended minimum group. A tank that fits one species might not hold a proper group of two of them, and the check doesn't add species together. Use it to rule fish out, then plan the mix.

Shrimp

Cherry shrimp (Neocaridina davidi) reach 3–4 cm as adults according to University of Florida IFAS (University of Florida IFAS Extension²). Dennerle recommends about pH 7.0–7.5, GH 6–7 and KH about 1 for Neocaridina (Dennerle³). Neither source gives a minimum tank size, so shrimp aren't in the checker. To make water to those values from RO, see remineralize RO water.

What isn't here

We left out species we couldn't source from one consistent reference. Otocinclus, a common nano suggestion, had no profile we could read. If you'd like a species added, email hello@mosspearl.com.

Sources for this page

1Seriously Fish: Species profiles (one per fish, linked in the table)Read Oct 19, 2026
2University of Florida IFAS Extension: Cherry shrimp Neocaridina davidi (EENY-751)Read Oct 19, 2026
3Dennerle: Shrimp King Shrimp Salt GH/KH+: dosage and recommended valuesRead Oct 19, 2026

Every figure above traces to one of these. Formulas are on Methods. Found an error? hello@mosspearl.com