Armored stickleback
Indostomus paradoxus
A tiny, armor-plated freshwater stickleback-like fish that is peaceful yet highly demanding. It requires live micro-foods and must be kept in a species-only or extremely peaceful tank.
Water Temperature
26 - 30 °C
pH Value
5 - 6.5
Water type
Freshwater
Tank level
Bottom
Adult size
3 cm
Minimum tank volume
>= 30 L
Minimum group
>= 1
GH
0 - 5 dGH
KH
1 - 2 dKH
TDS
10 - 95 ppm
Conductivity
16 - 148 uS/cm
Species description
Geographical Origin and Habitat: Native to Southeast Asia, particularly Myanmar (Burma), where it inhabits still waters, peat swamps, heavily vegetated ponds, and very slow-flowing streams with thick leaf litter and aquatic plants.
Taxonomy and Morphology: Belongs to the family Indostomidae, genus Indostomus. Features an elongated, slender body covered in protective bony plates arranged in longitudinal rows, resembling a miniature crocodile. Reaches a maximum adult size of only 2.5 to 3 centimeters.
Social Behavior: Peaceful, cryptic, and extremely slow-moving species. They are not schooling fish but tolerate and benefit from the presence of conspecifics in groups of 5-6 individuals if plenty of hiding places are provided.
Coloration and Sexual Dimorphism: Body coloration ranges from light brown to sandy beige with dark transverse bands and olive hues that aid camouflage in leaf litter. Sexual dimorphism is visible in mature males, which exhibit elongated and curved pelvic fins, and more developed dorsal and anal fins with dark edges.
Care, breeding and tankmates
Aquarium Setup: Requires small dedicated aquariums (nano tanks starting from 30-40 liters) with dense fine vegetation, mosses (Taxiphyllum, Vesicularia), and a soft substrate topped with oak or catappa leaves. Small pipes or bamboo tubes are essential as shelter.
Diet and Feeding: A highly specialized micro-predator that accepts almost exclusively small live foods such as baby brine shrimp, copepods, newborn daphnia, and microworms. They categorically refuse dry flakes or pellet foods.
Water Quality: Demands clean and well-filtered water with very gentle current. Optimal parameters: temperature between 22 and 26°C, slightly acidic to neutral pH (6.0 - 7.5), and low to medium water hardness (GH 3-10).
Compatibility and Cohabitation: A species-only tank is highly recommended. If tankmates are chosen, they must be extremely small and peaceful, such as freshwater shrimp (Neocaridina) or tiny surface fish (e.g., Boraras), to ensure the Indostomus is not outcompeted for food.
Aquarium Breeding: Possible in captivity. Eggs are deposited inside small crevices or narrow tubes, where the male guards and fans them until they hatch. Fry require infusoria and rotifers as their first food.
Risks and Diseases: The primary risk is starvation due to lack of suitable live foods or active food competition. They are also sensitive to sudden water parameter fluctuations and high levels of nitrogenous waste (ammonia and nitrites).
Geographic Origin and Distribution
Native to Southeast Asia, particularly Myanmar (Burma), where it inhabits still waters, peat swamps, heavily vegetated ponds, and very slow-flowing streams with thick leaf litter and aquatic plants.
Origin
South and Southeast Asia
Fish profile
- Temperament
- Semi-aggressive
- They have a completely peaceful, almost cryptic temperament. They are shy and deliberate, moving very slowly to stalk their tiny prey. They rely heavily on camouflage and hiding places to feel secure in the aquarium.
- Diet
- Omnivore
- They are strict micro-predators that often refuse dry foods entirely. Their diet must consist of live micro-foods such as microworms, newly hatched brine shrimp, and daphnia. Occasionally, they can be trained to accept frozen baby brine shrimp, but live food is essential.
- Life expectancy
- 3-5 years
- In captivity, this tiny armored stickleback typically lives between 3 and 5 years, though it can reach up to 7 years under optimal conditions. Its long-term survival depends strictly on a constant supply of live foods of appropriate size. A stable environment, free of sudden chemical fluctuations and with minimal nitrates, ensures a healthy and long life.
- Adult size
- 3 cm
- The catalog's scalar value is 3 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 3 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Indostomus paradoxus (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Pair
- Sexing them is challenging; males possess larger pelvic fins that are uniquely shaped to clasp the female during mating. Females are slightly plumper when carrying eggs. A small group will naturally pair off.
- Feeding frequency
- Twice daily
- Because of their tiny stomachs and slow hunting style, they should be fed small amounts once or twice daily. Ensure food reaches their specific location, as they will not actively chase it across the tank. Target feeding with a pipette is highly recommended.
- Bioload
- This tiny, pipefish-like creature produces an extremely low bioload. They are incredibly small, meaning their waste output is practically negligible. However, they require pristine water conditions, so regular maintenance and efficient biological filtration are mandatory.
- Flow
- Stagnant
- They require very low to almost stagnant water flow, similar to their native heavily vegetated swamps. Strong currents will blow them around and prevent them from hunting effectively. Gentle sponge filtration is the only appropriate choice for their aquariums.
- Reproduction
- Oviparous
- They are cave spawners, laying small clutches of eggs inside tiny tubes, such as bamboo sections. The male takes on the responsibility of guarding the eggs until they hatch. The fry are microscopic and require infusoria as their first food.
- Compatibility & tankmates
- They are exceedingly peaceful and easily outcompeted for food by almost any other fish. They are best kept in a species-only tank or with very small, peaceful nano fish and dwarf shrimp. Never keep them with anything aggressive, fast, or large enough to eat them.
- Tank level
- Bottom
- They exclusively inhabit the bottom levels, intricately navigating through leaf litter, moss, and dense planting. The tank must be heavily structured with botanicals and fine-leaved plants to provide security. They despise open, brightly lit spaces.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.3 ± 0.32 se
- Phylogenetic uniqueness (PD50)
- 0.75
- Bayesian Length-Weight
- a = 0.00389, b = 3.12
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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