FishMarineIntermediate
©AI Generated·Proprietary
Green-belly Cardinalfish
Zoramia viridiventer
A delicate, translucent cardinalfish featuring a radiant green iridescence on its belly. This peaceful, nocturnal species thrives in large schools among branching SPS corals in mature reef tanks.
Water Temperature
24 - 28 °C
pH Value
8.1 - 8.4
Water type
Marine
Tank level
Middle
Adult size
4.2 cm
Minimum tank volume
>= 80 L
Minimum group
>= 5
KH
8 - 12 dKH
Species description
Geographical Origin and Habitat: Indo-Pacific, ranging from East Africa to the Philippines and northern Australia. Shelters in dense aggregations among branching Acropora corals in sheltered bays at depths of 2 to 17 meters. Distributed in the Indo-West Pacific, this species inhabits sheltered coral reefs, commonly living in large groups among the branches of Acropora corals.
Taxonomy and Morphology: Part of the Apogonidae family, genus Zoramia. Features a glassy, semi-translucent oval body and large eyes. Reaches a maximum length of 4.2 cm (1.65 inches). Features a semi-transparent, deep, laterally compressed body with large dark eyes typical of nocturnal fish. The mouth is wide and adapted for catching plankton.
Social Behavior: Peaceful and schooling. Must be kept in a group of at least 5-8 individuals to prevent extreme stress. Hovers in tight groups during the day. Peaceful and shoaling behavior. Forms tight groups that hover motionless near protective coral branches during the day, dispersing at night to feed.
Coloration and Sexual Dimorphism: Semi-transparent body with silvery reflections and a bright green hue on the belly. No visible external sexual dimorphism. The coloration is translucent with silvery reflections and a distinctive iridescent green belly area. No apparent external sexual dimorphism.
Care, breeding and tankmates
Aquarium Setup: Minimum tank size of 80 liters (20 gallons) with branching SPS corals (like Acropora) for shelter. Matured filtration and stable reef parameters are preferred. Requires a mature reef aquarium of at least 100 liters (26 gallons) with shaded areas and branching coral structures where the school can shelter.
Diet and Feeding: Carnivorous zooplanktivore. Requires multiple daily feedings of cyclops, copepods, and baby brine shrimp. Rarely accepts dry food. Diet should focus on small zooplankton and crustaceans. Feed frozen artemia, mysis, copepods, and high-quality small-sized dry foods.
Water Quality: Maintain stable reef parameters: temperature 24-28°C (75-82°F), pH 8.1-8.4, specific gravity 1.022-1.025, and KH 8-12. Keep nitrate and phosphate levels low. Stable water conditions are key: temperature 24-28°C, pH 8.1-8.4, specific gravity 1.020-1.025. Moderate water movement is preferred over strong jets.
Compatibility and Cohabitation: Carnivorous zooplanktivore. Requires multiple daily feedings of cyclops, copepods, and baby brine shrimp. Rarely accepts dry food. Ideal for peaceful reef community tanks. Avoid housing with aggressive, territorial species or large predators that might view them as food.
Aquarium Breeding: Reef-safe. Best housed with peaceful species like gobies and small clownfish. Do not house with fast-swimming, aggressive fish. Paternal mouthbrooder. The male holds the fertilized eggs in his mouth, protecting and aerating them until they hatch, refusing food during this time.
Risks and Diseases: Very delicate and sensitive to shipping stress. Prone to starvation if not fed frequently. Vulnerable to bullying by aggressive tankmates. Fairly hardy, but susceptible to temperature fluctuations and secondary bacterial infections if water quality is not properly maintained.
Geographic Origin and Distribution
Indo-Pacific, ranging from East Africa to the Philippines and northern Australia. Shelters in dense aggregations among branching Acropora corals in sheltered bays at depths of 2 to 17 meters. Distributed in the Indo-West Pacific, this species inhabits sheltered coral reefs, commonly living in large groups among the branches of Acropora corals.
Origin
Tropical oceans and reefsAfrica and MadagascarSouth and Southeast AsiaAustralia, New Guinea, and Oceania
Fish profile
- Temperament
- Peaceful
- The Yellowbelly Cardinalfish is exceptionally docile and timid, making it a perfect resident for a tranquil reef environment. It prefers to observe its surroundings quietly rather than actively engaging with other fish. Keeping it in a small group or school can significantly reduce its shyness and encourage more natural behaviors. It will rarely, if ever, show aggression toward any other aquarium inhabitants.
- Diet
- Carnivore
- In its natural habitat, the Yellowbelly Cardinalfish is a nocturnal planktivore that feeds on tiny crustaceans suspended in the water column. In captivity, it readily accepts a variety of small, meaty foods such as frozen cyclops, baby brine shrimp, and finely chopped mysis. It can also be trained to accept high-quality micro-pellets or flakes over time. Offering a varied diet ensures optimal health and vibrant coloration.
- Life expectancy
- 3-5 years
- The Greenbelly Cardinalfish is a delicate species with a captive lifespan typically ranging from 3 to 5 years under optimal aquarium conditions. Due to their small size and sensitivity, maintaining pristine water quality and a stress-free environment is critical to maximizing their longevity. In captivity, their lifespan can be shortened by competitive tankmates or inadequate feeding, making targeted care essential. Providing them with a secure habitat with plenty of branching corals helps reduce stress and promotes a healthier, longer life.
- Adult size
- 4.2 cm
- The catalog's scalar value is 4.2 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 4.23 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Zoramia viridiventer (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
- Group
- Telling males and females apart can be challenging, as the Yellowbelly Cardinalfish exhibits minimal sexual dimorphism. Males may occasionally display a slightly larger jaw structure, especially during the breeding season when preparing to mouthbrood. For the best chances of forming a compatible pair or a small shoal, purchasing a group of individuals is recommended. They generally coexist peacefully in small groups within adequate space.
- Feeding frequency
- 2-3 times daily
- Due to its small stomach and active metabolism, this species benefits from frequent, small feedings. Providing food 1 to 2 times daily is generally sufficient to maintain its weight and health. Since it naturally feeds during twilight and nocturnal hours, offering food when the main aquarium lights are dim can encourage better feeding responses. Target feeding may be necessary if tank mates are aggressive eaters.
- Bioload
- The Yellowbelly Cardinalfish (Zoramia viridiventer) produces a relatively low bioload compared to larger reef fishes. Due to its small size and efficient digestion, it contributes minimally to the aquarium's overall waste accumulation. Standard protein skimming and regular water changes are usually sufficient to maintain pristine conditions. It is an excellent choice for smaller setups or heavily stocked reef tanks.
- Flow
- Moderate
- The Yellowbelly Cardinalfish prefers areas of gentle to moderate water flow where it can easily hover and capture passing plankton. Extremely strong or chaotic currents can exhaust this small fish and force it to hide continuously. Creating sheltered zones within the rockwork allows it to rest peacefully during the day. A well-balanced flow dynamic ensures it receives food without expending unnecessary energy.
- Jump risk
- No
- Reproduction
- Mouthbrooder
- Zoramia viridiventer are paternal mouthbrooders, a fascinating reproductive strategy common among cardinalfishes. After a complex courtship dance, the female releases eggs which the male quickly fertilizes and scoops into his mouth. The male incubates the eggs for several weeks, during which he generally refuses to eat. Once the fry hatch, they are released into the water column to fend for themselves.
- Compatibility & tankmates
- Aggressive
- This cardinalfish is incredibly peaceful and makes an ideal addition to a community reef aquarium. It poses no threat to corals, invertebrates, or other small, docile fishes. However, its small size and passive nature make it vulnerable to aggressive or large predatory tank mates. It should be housed with similarly peaceful species such as gobies, blennies, and small wrasses.
- Tank level
- Middle
- This cardinalfish predominantly occupies the middle sections of the water column. During the day, it tends to hover motionless near branching corals, rock overhangs, or artificial structures. As the lights dim, it becomes more active and ventures further into open water to hunt for plankton. Providing vertical structures like sea whips or branching SPS corals mimics its natural sheltering behavior.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.3 ± 0.5 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5156
- Bayesian Length-Weight
- a = 0.01514, b = 3.07
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
