Nightfish

Interesting Info

• The Nightfish is a freshwater fish found only in the rivers and wetlands of southwestern Western Australia, making it an endemic species.
• They are a deep-bodied fish, coloured dark brown to olive with mottled markings, giving them excellent camouflage among woody debris and aquatic plants.
• Their name comes from their nocturnal habits — they spend the day hidden under logs or in shaded banks, becoming most active at night.
• Nightfish prefer slow-flowing rivers, lakes, swamps, and billabongs, especially those with submerged logs, vegetation, and sandy or muddy bottoms.
• They are ambush predators, feeding mostly on insect larvae, worms, and small crustaceans, though larger individuals also take small fish.
• Their range is restricted to the southwest corner of WA, from the Moore River near Perth down to the Kalgan River near Albany..
• Populations have declined in some areas due to salinity, habitat loss, reduced stream flows, and invasive fish such as gambusia and trout.
• Adults usually grow to 12–15 cm (5–6 in), though some individuals can reach 20 cm (8 in).
• Breeding occurs in late winter to spring (August–October). Females scatter adhesive eggs among aquatic vegetation and woody debris, with no parental care once spawning is complete.
• Juveniles grow slowly and rely heavily on dense vegetation for cover from predators.
• Lifespan is relatively long for a small fish, with individuals known to live 6–8 years.