Diamondfish
Monodactylus argenteus
Diamondfish (Monodactylus argenteus) is a laterally compressed silver schooling fish found in coastal estuaries, mangroves, and lower freshwater reaches. It is hardy and often kept in brackish aquaria; in the wild it feeds on small invertebrates and algae.
Identification points
- Deep, diamond-shaped body with very strong lateral compression
- Bright silver body with dusky vertical bars/lines, especially in juveniles
- Long, pointed dorsal and anal fins with a deeply forked tail
Habitat
Shallow estuaries, mangrove creeks, tidal rivers, and sheltered coastal lagoons; juveniles commonly enter brackish and even fresh water, while adults are usually in low-salinity coastal waters.
Bait notes
Small pieces of shrimp, bloodworms, sandworms, and finely chopped marine bait work well; tiny soft plastics or bead-rigged bait can also take fish. Because it is small-mouthed, use small hooks and light terminal tackle.
Behavior
Schooling and highly mobile, the species forages through the water column and around structure, picking at zooplankton, small crustaceans, worms, and plant material. It is most active in calm, shallow habitat and can be wary in clear water.
Caution
Sharp, spiny dorsal and anal fins can prick handlers; use care when unhooking. Check local rules, as some areas manage estuarine species and export/possession may be restricted.
Fishing notes
Fish light in mangrove edges, creek mouths, and tidal channels with a slow drift or gentle float presentation. Short casts near structure and subtle retrieves are best; many captures are incidental rather than targeted.