Butis
Butis is a genus of freshwater fish belonging to the family Butidae. These fish, commonly known as sleeper gobies, are characterized by their elongated, eel-like bodies and a distinctive, “sleeper-like” behavior. They are predominantly found in the Indo-Pacific region, inhabiting a variety of freshwater environments, including rivers, streams, and lakes.
Characteristics
Butis species are generally small to medium in size, with most species reaching lengths of 10-20 centimeters. They possess a slender, serpentine body shape, with a pointed head and a slightly compressed, elongated body. Their mouths are positioned at the tip of the snout and are equipped with small, sharp teeth. Unlike most gobies, which have fused pelvic fins forming a suction disc, Butis species have free pelvic fins. Their dorsal fin is long and continuous, extending from the head to the tail. They also have a prominent anal fin and a caudal fin that is typically rounded or slightly forked.
Butis species display a unique behavioral trait known as "sleeping," which is characterized by their ability to lie motionless on the bottom of their habitat for extended periods. This behavior, which is particularly pronounced during the day, is believed to be a form of camouflage that helps them evade predators. They are primarily nocturnal feeders, using their sharp teeth to capture insects, crustaceans, and other small invertebrates.
Habitat and Distribution
Butis species are widely distributed throughout the Indo-Pacific region, with a range that extends from India and Southeast Asia to Australia and the Philippines. They are predominantly found in freshwater environments, including rivers, streams, and lakes. They are typically found in areas with dense vegetation, debris, or other cover, which provides them with protection from predators and a suitable habitat for foraging.
Species
The genus Butis currently comprises approximately 15 recognized species. Some of the most commonly encountered species include:
- Butis butis (Hamilton, 1822) – Common sleeper goby
- Butis melanostomus (Bleeker, 1852) – Blackmouth sleeper goby
- Butis koilomatodon (Bleeker, 1853)
- Butis amboinensis (Bleeker, 1853)
- Butis blossi (Whitley, 1951)
Conservation
Most Butis species are not considered to be threatened or endangered, and their populations are generally stable. However, certain species, particularly those with restricted ranges or facing habitat loss, may be more vulnerable.