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FishBrackishMarineIntermediate

African Mono

Monodactylus sebae

This remarkably tall, diamond-shaped silver fish originates from West African estuaries. It is a fast, active schooling species that requires a large aquarium transitioning to full marine conditions.

Taxonomy

Class:Actinopteri

Order:Perciformes

Family:Monodactylidae

Genus:Monodactylus

Species:Monodactylus sebae

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Water Temperature

24 - 28 °C

pH Value

7.5 - 8.5

Water type

Brackish / Marine

Tank level

Middle

Adult size

25 cm

Minimum tank volume

>= 300 L

Minimum group

>= 6

Species description

Geographical Origin and Habitat: This species is widely distributed along the coast of tropical West Africa, from Senegal southward to Angola. It primarily inhabits river estuaries, brackish lagoons, mangrove swamps, and coastal harbors. Juveniles spend most of their time in freshwater or low-salinity brackish habitats, migrating to full marine conditions as they reach adulthood.

Taxonomy and Morphology: Belonging to the family Monodactylidae. It features an exceptionally deep, laterally compressed body, giving it a diamond-like or triangular silhouette due to the high profile of the dorsal and anal fins. Adults can reach up to 20-25 centimeters in vertical height, often exceeding their overall body length.

Social Behavior: An extremely active, fast-swimming schooling species that needs to be kept in groups of at least 5-6 individuals. Solitary specimens or pairs often experience chronic stress, leading to extreme shyness, refusal to feed, or heightened aggression toward other peaceful tankmates.

Coloration and Sexual Dimorphism: The base body coloration is a brilliant, reflective silver, accented by four dark vertical bands (black or dark brown) that cross the head and anterior body. These bands are prominent in juveniles and fade slightly as the fish ages. The anal and dorsal fin tips are yellowish-gold. There is no visible external sexual dimorphism.

Care, breeding and tankmates

Aquarium Setup: Requires a very large aquarium, with a minimum capacity of 90-100 gallons (approx. 350-400 liters) for a small school. Ample open swimming space is critical. The aquascape should feature sturdy structures like large rocks and driftwood roots along the perimeter. Live plants should be avoided as they will likely be eaten.

Diet and Feeding: Voracious, opportunistic omnivores. In the aquarium, they require a varied diet containing high-quality frozen foods like mysis shrimp, krill, and chopped seafood, along with an essential plant component such as spirulina flakes, nori seaweed, and blanched spinach. They will readily eat high-quality pellets and flakes.

Water Quality: While young specimens can adapt to hard freshwater, long-term health and adult survival require brackish (SG 1.005-1.015) or full marine conditions (SG 1.020-1.024). Keep the temperature between 24 and 28°C and pH at 7.8-8.4. Powerful mechanical and biological filtration is necessary to manage their waste production.

Compatibility and Cohabitation: Excellent tankmates include active, robust brackish species of similar size, such as Archerfish (Toxotes), Scats (Scatophagus), and large gobies. Do not house them with small, delicate, or slow-moving fish that could be stressed by the monos' rapid swimming habits or eaten. Generally reef-safe but may eat tiny shrimp.

Aquarium Breeding: Spontaneous spawning in home aquaria has not been successfully documented. In the wild, they are pelagic spawners, releasing eggs in full marine coastal waters. Commercial breeding is achieved in large facilities using hormonal stimulation and specialized salinity-shifting regimes.

Risks and Diseases: Quite hardy if kept in appropriate salinity. However, keeping them in freshwater long-term weakens their immune system, making them susceptible to skin parasites like Oodinium and Marine Ich. They are sensitive to high nitrate levels, so weekly water changes of 20-30% are highly recommended.

Geographic Origin and Distribution

This species is widely distributed along the coast of tropical West Africa, from Senegal southward to Angola. It primarily inhabits river estuaries, brackish lagoons, mangrove swamps, and coastal harbors. Juveniles spend most of their time in freshwater or low-salinity brackish habitats, migrating to full marine conditions as they reach adulthood.

Origin

Tropical oceans and reefsNorth AmericaAfrica and Madagascar

Fish profile

Temperament: Aggressive
Diet: Omnivore
Sex ratio: School
Feeding frequency: TWO_THREE_DAILY
Bioload: This fish produces a high bioload. It grows large and is very active. Excellent filtration and regular water changes are a must.
Flow: Strong
Jump risk: No
Reproduction: Hermaphrodite
Compatibility & tankmates: Community
Tank level: Middle

FishBase

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level: 3.9 ± 0.64 se
Phylogenetic uniqueness (PD50): 0.625
Bayesian Length-Weight: a = 0.02188, b = 3.02

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

Related species

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Variants and close relatives

Same atlas type, nearby scientific identity, genus, or family.

Singapore Mono

Monodactylus kottelati

Species description

Care, breeding and tankmates