MONO ANGELFISH (Monodactylus Argenteus)

Know Your Fish

Monodactylus Argenteus is commonly called as Sea Angel, Mono Angelfish, Silver Moony, Silver Batfish, Diamond moonfish etc. This fish is native to coastal areas of Eastern Africa, Red Sea, South East Asia & Australia. This fish starts its life in Estuaries & Swims to the ocean as it grows. They are Shoaling Fish mostly feeding on vegetation, smaller aquatic life. Mono Angelfish are known to grow up to 12 inches & live for 7 years or more. The Mono Angelfish in the hobby is wild caught 'assuming' there is no reliable source confirming or duplicating Breeding in an home Aquarium nor any information on Sexual Dimorphism. Mono Angelfish can be kept in a home aquarium by understanding their water parameters & providing them with the right conditions as they age. Below information on Mono Angelfish will help you further.


More then 5 years, few have known to live for 7 to 10 years.


No Visual differences Between Male & Female


No Visual differences Between Male & Female

Mono Angelfish Aquarium Care

Fish with a triangular silver body, yellow fins & big eyes, schooling in an Aquarium is a treat to watch. Few things to keep in mind when getting this lovely fish home. What makes it interesting keeping a Mono Angelfish in an Aquarium is that they start as Freshwater fish with higher level of salinity, then the requirement changes to Brackish water & as Adults they can be in a full Saltwater tank. This process is called 'Osmoregulation in fish'. Since the water condition needs to be monitored on Specific Gravity & increased with the age of Mono Angelfish & change the Aquarium water condition from freshwater to brackish, brackish to Saltwater, most avoid getting this fish. However its not as difficult as it sounds, below information will help setting up a Tank & understanding the water parameter requirements for this fish.

Tank Size for Mono Angelfish

Minimum 50 Gallon (189 liters) for Juveniles & 120 Gallon or bigger for Adult Sea Angel's. The bigger the tank, the better!

Temperature Range

75°-82 °F (23.8°-27.7 °C )

pH Range

7.5 to 8.5 is the pH range for Silver Moony's ( there should never be drastic change's in the pH level)  

Water hardness

10 to 15 dGH for Juveniles in freshwater & in brackish tanks you would measure specific gravity starting from 1.008 upwards to 1.025 as they grow into adults.


Mono Angelfish are Omnivores, in their natural habitat they eat plant matter, smaller aquatic animals & insects. In an aquarium Pellets, Flakes, Freeze Dried worms, Live Food & Spinach, Lettuce, Boiled Pea's, Zucchini etc can be fed. Spirulina based food must be their staple food, protein based food should be fed every 3 to 4 days once.

Tank Decoration Mono Angelfish

Firstly start at least a minimum of 50 Gallon (190 liter) if not 120 Gallon straight Freshwater  Aquarium for Juveniles. The Tank should be a Freshwater Tank with higher salinity, for tank decoration Brackish water plants can be selected but not mandatory, rocks & sand for tank bottom. Most freshwater plants cannot withstand higher salt in water & would die,  once the Aquarium is established look for minimum 5 to 7 Juveniles kept in Freshwater around the size of one inch. Acclimate the fish to the Established Tank. Ensure the filtration is good as the bio-load is on higher side. The tank should have a lot of open swimming space, these fish mostly are middle is surface dwellers. They are really fast, hence lot of open swimming area is required in a Mono Angelfish aquarium.

Tank Mates Mono Angelfish

Scat fish (Scatophagus argus), African moony / Silver moony (Monodactylus sebae) Orange chromide, Green Chromide, Brackish water mollies, Ceylon puffer, Columbian Shark etc. All these fish make great tank mates for Silver Moony.

Mono Angelfish Breeding Information

Captive Breeding of Mono Angelfish is unknown. I have not bred them nor I have any reliable source confirming successful breeding till date. I thoroughly understand the reason why its difficult to breed them though. In the wild they move out of brackish environment to Ocean as adults & swim back to brackish water estuaries for breeding. What triggers spawning is unknown, it could be age, season, weather, salinity, trust me on this I'm as keen as you to know more about this fish's breeding behavior. More over visual differences between male & female Mono Angelfish is still unknown. Scientific studies on this fish have advanced as they contribute to Ornamental fish keeping. As of now the Juveniles are collected from wild, kept in fish farms in ponds until they reach desirable size to be sold in the Ornamental Fish Market. In case I ever have any reliable information or if they spawn in my Aquarium I will share it here.

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