Duckbill Sleeper Goby

Butis butis is found in estuaries, mangroves, and tidal rivers across the Indo-Pacific, where it is often overlooked due to its cryptic brown-mottled colouration and habit of hovering motionless at odd angles in the water column. It is a nocturnal ambush predator that waits for small fish and crustaceans to come within striking range before lunging with great speed.

Water: 22–28 °C, pH 7.0–8.5, specific gravity 1.003–1.012; low to moderate brackish. Tank: 120 L minimum; provide roots, caves, and dense décor where the fish can wedge itself at angles. Feeding: Carnivorous; frozen prawns, fish, bloodworm; live feeder shrimp initially to wean onto frozen. Behaviour: Nocturnal ambush predator; hangs motionless among décor during the day. Compatibility: Can be kept with fish too large to eat; will take anything small enough.