Silver Moony / Mono

Geographic Origin and Biotope: Indo-Pacific (East African coasts, Asia, Australia). Inhabits tidal river estuaries, muddy marinas and mangrove swamps. Constantly oscillates between fresh water, brackish and ocean.

Taxonomy and Morphology: Mono / Silver Moony (Monodactylus argenteus). Imposing perfectly rhomboidal fish (like an Angelfish but without filiform fins) with a laterally flattened body to move among submerged roots.

Social Behavior: Shoaling species. Very fast, nervous and darting. Will become skittish (terrified) if kept individually. Prefers schools of at least 5-6 specimens.

Coloration and Sexual Dimorphism: Plated in quicksilver, hyper-reflective. Two vertical black bands pass over the head. The dorsal fin is typically tinged with bright sun yellow in juveniles (hence "Moony"). Sexes are virtually identical.

Aquarium Setup: Colossal tanks (min. 150-200 cm / 60-80 inches). It is a "sprint" swimmer, needing huge central open spaces and oceanic currents generated by wavemakers. Furnishing limited to fake mangrove woods.

Diet and Feeding: Marine omnivore. As a juvenile it eats spirulina, larvae and insects. As an adult it needs fish flesh, shelled shrimp, mysis and large protein pellets for cichlids or predators.

Water Quality: The Brackish Deception. Juveniles (those sold in stores) can be in very hard freshwater, but *must* be gradually transitioned to heavy brackish water (SG 1.010 - 1.015) or pure marine as they grow.

Compatibility and Tankmates: Predator for small fish. Once adult (25 cm / 10 inches high) it will devour Neons or Guppies. Only paired with other brackish monsters (Archerfish, Scats, Pufferfish).

Aquarium Reproduction: Undocumented in normal home aquariums. In nature they spawn in the salty Ocean (pelagic) and the fry swim up the river mouths into fresh water.

Risks and Diseases: Death by Osmosis in Community Aquarium. Sadly sold as a "weird little silver freshwater fish". At 1 year of age, if not transferred to a saltwater vat, its liver or kidneys will collapse and it will die.