Common Name: Mono Argentus
Scientific Name: Monodactylus argenteus
Other Names: Silver Moony, Silver Mono, Moonfish, Fingerfish
The Mono Argentus is a striking, deep-bodied fish known for its laterally compressed, almost diamond-shaped silver body with yellow and black accents on the dorsal and anal fins. This species is highly adaptable and can thrive in freshwater, brackish, and marine environments. It is an active schooling fish that requires ample swimming space, making it a popular choice for large aquariums.
Habitat and Distribution:
Native to the Indo-Pacific region, Monodactylus argenteus is found along the coasts of East Africa, India, Australia, and Southeast Asia. It inhabits estuaries, mangroves, and tidal rivers where salinity fluctuates. Juveniles are often found in freshwater or low-salinity environments, while adults prefer brackish to full marine waters.
Size and Lifespan:
This species can grow up to 8-10 inches (20-25 cm) in captivity, with wild specimens occasionally reaching slightly larger sizes. With proper care, they can live for 7-10 years.
Diet and Behavior:
Mono Argentus is an omnivore with a diet that includes small crustaceans, plant matter, algae, and detritus. In captivity, they should be offered a varied diet of high-quality omnivore pellets, flake foods, spirulina, frozen or live foods such as brine shrimp, bloodworms, and chopped tilapia. They are highly active, social fish that must be kept in groups of at least five to prevent stress and aggression.
Breeding and Reproduction:
Breeding Monodactylus argenteus in captivity is extremely rare, as they require brackish to full marine conditions for successful spawning. In the wild, they spawn in coastal waters, where their larvae develop before migrating into estuaries. There are no well-documented cases of captive breeding in home aquariums.
Aquarium Care and Tank Requirements:
A minimum of 125 gallons is required for a group of juveniles, with a larger tank (180+ gallons) necessary for adults. Their ideal tank setup includes a sandy substrate, driftwood, and rock formations for aesthetics, strong filtration with high oxygenation, moderate to strong water flow to mimic tidal environments, and a gradual transition from freshwater to brackish as they mature.
Ideal Tank Mates:
Mono Argentus are peaceful but fast-moving and should be housed with similarly sized, brackish-compatible fish. Suitable tank mates include Scats, Archerfish, Colombian Shark Catfish (Ariopsis seemanni), Brackish Puffers, and other large, active fish that can tolerate brackish conditions. Avoid slow-moving or small fish that may be outcompeted for food.
Difficulty Level:
Intermediate to Advanced. They require a transition to brackish water as they mature, a large tank, and a well-oxygenated environment.
Water Parameters:
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Temperature: 75-82°F (24-28°C)
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pH: 7.5-8.5
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General Hardness (GH): 10-20 dGH
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Carbonate Hardness (KH): 8-15 dKH
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Salinity: 1.005-1.018 SG (brackish to marine)
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Ammonia: 0 ppm
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Nitrite: 0 ppm
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Nitrate: <20 ppm (regular water changes required)
Additional Information:
- Juveniles can survive in freshwater but should gradually be transitioned to brackish water as they grow.
- A strong current is beneficial, as they originate from tidal environments.
- They are fast swimmers and need ample space to prevent stress.
The Mono Argentus is a fascinating and visually stunning fish that thrives in a well-maintained, brackish-water aquarium. With proper care, it makes a rewarding addition for aquarists who can accommodate its space and salinity requirements.
