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Green Scat

Scatophagus argus

A disc-shaped, voracious omnivorous scavenger decorated with spots, requiring full marine conditions as an adult and highly spacious tanks.

Taxonomy

Class:Actinopteri

Order:Perciformes

Family:Scatophagidae

Genus:Scatophagus

Species:Scatophagus argus

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Water Temperature

22 - 28 °C

pH Value

7.5 - 8.5

Water type

Freshwater

Tank level

Middle

Adult size

30 cm

Minimum tank volume

>= 300 L

Minimum group

>= 1

15 - 30 dGH

7 - 15 dKH

TDS

295 - 600 ppm

Conductivity

461 - 938 uS/cm

Species description

Geographical Origin and Habitat: Indo-Pacific (Kuwait, Japan, Fiji). Estuary par excellence. Lives in dense mangrove forests, polluted ports, muddy river mouths and currently swims up into freshwater sections.

Taxonomy and Morphology: Spotted Scat (Scatophagus argus). Scatophagid. Compressed and tall disc body (almost square), with a very small head compared to its size. The first rays of the thick dorsal fin are robust (and slightly venomous) spines.

Social Behavior: Demolition squad. Very sociable and schooling fish, swims constantly up and down the glass waiting for food. Extremely active, curious and fearless; explores every element of the tank with its mouth.

Coloration and Sexual Dimorphism: The "Leopard" (Argus). Silvery, bronze or bright olive green background, densely covered (especially in youth) with large black circular spots (polka dots). As an adult (at 30 cm / 12 inches) the spots fade and merge, making it a dark bronze color. There is a variant with a reddish head (Red Scat).

Care, breeding and tankmates

Aquarium Setup: Huge Brackish Tank (Minimum 150 cm / 60 inches). Freshwater tolerated only by juveniles. Plants forbidden (they eat all of them except Java fern and fake ones). Layout with large intertwined trunks (mangroves) and solid rocks. A lot of empty space for swimming is needed.

Diet and Feeding: The Everything-Grinder Omnivore. Its Latin name literally means "Feces eater" (because it sweeps port drains). Devours algae, salad, peas, floating pellets, minced fish, shrimp. Greatly appreciates filamentous algae.

Water Quality: Saline Transition. Juveniles in stores are kept in freshwater (high GH, alkaline). As they grow (beyond 10 cm / 4 inches), they MUST be brought to heavy brackish water (Specific Gravity 1.010 - 1.015) up to pure marine water, otherwise they will waste away irremediably.

Compatibility and Cohabitation: Brackish Community. The perfect companion for estuary fish: Monodactylus (Argenteus and Sebae), Toxotes (Archerfish), and Brackish Pufferfish (Tetraodon biocellatus). Devours any small fish or crustacean.

Aquarium Breeding: Never documented in private closed systems. They require migration from the estuary (where they grow) to the open sea (where they lay pelagic eggs), and vice versa for the larvae. Space and chemical variations impossible to replicate.

Risks and Diseases: Freshwater Syndrome. Many buy them as "freshwater fish". After a year in water without marine salt, their immune defenses collapse: the fish becomes, develops white clouds on its eyes (Eye Cloud), stops eating and dies from hepatic-osmotic block.

Geographic Origin and Distribution

Indo-Pacific (Kuwait, Japan, Fiji). Estuary par excellence. Lives in dense mangrove forests, polluted ports, muddy river mouths and currently swims up into freshwater sections.

Origin

Tropical oceans and reefsEast Asia

Fish profile

Temperament: Semi-aggressive
Diet: Omnivore
Sex ratio: Solitary
Feeding frequency: Twice daily
Bioload: This fish grows very large and produces a massive bioload. Extremely powerful filtration is mandatory to keep the water safe. They are very messy eaters that require large, regular water changes.
Flow: Stagnant
Reproduction: Oviparous
Compatibility & tankmates: They are semi-aggressive and can nip the fins of slower fish. They are best kept in brackish communities with Monos and Archerfish. They will quickly devour any fish small enough to fit in their mouth.
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 ± 0.35 se
Resilience: High (less than 15 months)
Generation time: 0.9 years
Phylogenetic uniqueness (PD50): 0.8125
Bayesian Length-Weight: a = 0.03236, b = 2.92

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.

Variants and close relatives

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

African Scat

Scatophagus tetracanthus

Species description

Care, breeding and tankmates