Quick Stats
| Adult Size | 2–3 cm |
| Minimum Tank | 10 gal |
| Temperature | 16–24°C (unheated) |
| pH Range | 6.0–7.5 |
| Hardness (GH) | 5–15 dGH |
| Difficulty | Easy |
| Temperament | Peaceful, schooling |
| Diet | Omnivore — micro pellets, crushed flakes, frozen daphnia, baby brine shrimp |
| Schooling | 8+ required |
Tank Setup
Vietnamese Cardinal Minnows (Tanichthys micagemmaeus) are a smaller, more vibrant cousin of the White Cloud Mountain Minnow. They were only formally described in 2001 and are still rare in the hobby, but they're worth seeking out — the electric blue lateral stripe on males is genuinely stunning. A 10 gallon tank is plenty for a school of 10–12.
Water parameters: temperature 16–24°C (unheated in a normal house is ideal), pH 6.0–7.5, hardness 5–15 dGH. They prefer slightly softer water than White Clouds but tolerate a similar range. Like White Clouds, they suffer above 26°C — keep them cool.
Set up the tank with a dark sandy substrate, driftwood, and hardy plants (Java moss, Java fern, Anubias, Vallisneria). The dark substrate makes their blue stripe 'pop' visually. Floating plants (duckweed, frogbit, salvinia) diffuse the light and make them feel secure. A gentle sponge filter or small hang-on-back is plenty — they don't like strong current.
Tank Mates
Vietnamese Cardinal Minnows are peaceful, tiny, and completely non-aggressive. They work in any cold-water nano community where the temperature stays below 24°C. The only risk is being eaten — at 2–3 cm they are bite-sized for larger fish.
Compatible tank mates: other small cold-water species (Cherry Shrimp, Amano Shrimp, bladder snails, ramshorn snails, Malaysian Trumpet Snails), and small peaceful fish at the cool end of their range ( Ember Tetras at 23–24°C, Pygmy Corydoras). They coexist perfectly with White Cloud Mountain Minnows (similar temperature, similar temperament, different water-column use).
Avoid: any fish large enough to eat them (goldfish, rosy barbs, angelfish, bettas), tropical species that need 26°C+ (the cardinal minnow will slowly decline), and aggressive nano fish (dwarf puffers, male endler livebearers in small tanks). Do not house with shrimp-eating specialists if you want the shrimp to thrive.
Diet & Feeding
Vietnamese Cardinal Minnows are tiny omnivores with tiny mouths. They eat micro pellets, crushed flakes, frozen daphnia, frozen baby brine shrimp, and microworms. In a mature tank they graze on biofilm and micro-organisms among plants.
Feed small amounts twice daily — they have fast metabolisms and small stomachs. Crushed flake or micro pellets are the staple; supplement with frozen daphnia or baby brine shrimp 2–3 times per week for colour and condition.
They are surface and mid-water feeders, so floating or slow-sinking foods work best. Dry food should be crushed to a powder — their mouths are too small for standard flakes. A varied diet keeps the blue stripe vivid; flake-only diets fade them.
Common Health Issues
Vietnamese Cardinal Minnows are hardy when kept cool. The single biggest health issue is heat stress — people move them into a tropical tank 'for the winter' and they slowly decline. Sustained temperatures above 26°C suppress their immune system and shorten their lifespan.
Like all small fish, they are susceptible to ich when stressed by temperature swings. The standard heat-and-salt treatment works, but keep the treatment temperature below 25°C. They are sensitive to copper — many fish medications contain it; always check the label.
Lifespan is typically 3–5 years. They are short-lived for such a small fish (fast metabolism), but the school persists indefinitely once established. Captive-bred specimens are stronger than wild-caught; seek out tank-raised stock when possible.
Breeding
Vietnamese Cardinal Minnows are egg-scatterers and breed readily in a planted tank. They spawn in the early morning among Java moss or spawning mops, scattering 5–20 adhesive eggs per female over several hours. They eat their own eggs — remove adults for the best fry survival.
Sexing: males are smaller, brighter, with a vivid blue lateral stripe and red in the fins. Females are larger, rounder, and drabber with a silver lateral stripe. To breed deliberately, condition a group with high-protein frozen foods (baby brine shrimp, daphnia) for a week, then move to a planted 5–10 gallon tank with Java moss.
Eggs hatch in 36–48 hours. Feed fry infusoria for the first 3 days, then microworms and baby brine shrimp. They grow slowly — the fry are among the smallest in the hobby and need microscopic food for the first week. Patience is required; expect maybe 10–20 survivors from a spawning event.
Frequently Asked Questions
How is the Vietnamese Cardinal Minnow different from the White Cloud Mountain Minnow?
They are closely related (same genus, Tanichthys) but distinct species. Vietnamese Cardinals are smaller (2–3 cm vs 3–4 cm), have a brighter electric blue lateral stripe (vs the White Cloud's bronze-red), and prefer slightly softer water. Both are cold-water and unheated-tank suitable.
Do Vietnamese Cardinal Minnows need a heater?
No — they prefer 16–24°C and thrive in an unheated tank. Like White Clouds, they suffer above 26°C. An unheated tank in a temperate-climate house is ideal.
How many Vietnamese Cardinal Minnows should I keep together?
Eight is the absolute minimum; ten to twelve is better. They are a tight-schooling fish and a single individual will pine, lose colour, and hide. In a 10 gallon tank, 10–12 is the ideal school size.
Can Vietnamese Cardinal Minnows live with shrimp?
Yes — they are peaceful and too small-mouthed to eat adult Cherry Shrimp. They coexist perfectly with Cherry Shrimp, Amano Shrimp, and all snail species. They may eat shrimp fry but not at a rate that threatens the colony.