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Monodactylus argenteus



    This stunning fish uniquely adapts to increasing salinity over its lifetime. It is born in brackish estuaries and migrates out into coastal waters as an adult. Reproducing this rise in salinity is essential to their long lives in the aquarium where they can be acclimated to a life entirely in saltwater.
Quick stats:
Listed tank sizes are the minimum
Size: Common length : 4.7” (12.0 cm). Max length : 10.6” (27.0 cm)
Tank: Individual: 55-80 gallons (208.0-302.8 liters) or larger. School of 4-6: 75-100 gallons (283.9-378.5 liters) or larger. Long, rectangular tanks are recommended.
Strata: Top to mostly middle.
PH: 7.2-9.0
Hardness: Hard, dH: 8.0-14.0
Temperature: 72 – 82°F (24 – 28°C)


Order: Perciformes
Suborder: Percoidei
Family: Monodactylidae
Genera: Monodactylus argenteus


Common name:



    Butter Bream, Diamondfish, Diamond Moonfish, Fingerfish, Kitefish, Malayan Angel, Mono Argentus, Moonfish, Sea Angel, Silver Batfish, Silver Mono, Silver Moonfish, Silver Moony



EAST AFRICA, INDIA, AUSTRAILA, SOUTH ASIA. Occurs in shoals along coastlines, in estuaries, lagoons, tidal creeks. Brackish and sea water, seldom seen in fresh water.

General Body Form:Disk-shaped, like an Angelfish, but with shorter fins and a shorter snout. Dorsal and anal fins are elongated. Caudal fin is truncate to forked.

Coloration:Silvery body and head. Dorsal and anal fin tips range from yellow to black. Caudal fin outer rays and distal edge are dusted black. Large eyes are struck through with one or more vertical black bars.


  • Care:
    Moderate to Advanced
  • Water:
    BRACKISH/EURYHALINE: The aquarist must understand and be able to provide increasing salinity levels as this fish ages in order for the fish to survive. In nature young fish are found in mildly brackish, hard water estuaries. As they mature they migrate downstream, gradually adjusting to increases in salinity until they reach the ocean. There, adults acclimate to a fully saltwater environment.
  • Diet:
    OMNIVOROUS: These energetic eaters enjoy a diet rich in plant material (lettuce, kale, seaweed, spinach, spirulina) balanced with freeze-dried, frozen or live proteins (bloodworms, brine shrimp, fish fry, prawns, tubifex) as well as flake and pellet food.
  • Tank/Decor::
    Large, long aquariums with open water swimming spaces are most beneficial. For youth, a riverine/riparian biotope could be replicated with a substrate of either sand or small pebbles, freshwater plants and driftwood, branches or roots. As adults, these fish migrate from very brackish water to saltwater. A coastal environment can be replicated with a foundation of live rock and sand.
  • Communities::
    SEMI-AGGRESSIVE: Excellent fish for large, peaceful, non-competitive aquariums or a species-only tank. Solitary fish are very nervous. They are calmest when kept in schools of at least 4-6 of their own kind. Peaceful, not-too-small tank mates are advised as these fish may eat smaller fish and invertebrates. Archerfish, Mollies, Halfbeaks, Bream and Tarwhine are a few suitable companions.


    Brackish estuaries and the lower reaches of freshwater streams, frequently occurring among mangroves.


    Spawning has been unsuccessful in captivity. Sexual dimorphism is unknown.



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