Freshwater GobyAwaous commersoni

Category
  • Rivers
Tags
  • Fish
  • Goby
  • Critically endangered species

Description

This freshwater goby can be found throughout the Southwest Indian Ocean. It has two dorsal fins and is distinguished by its rather large head and fusiform body. It can measure between 10 to 25 centimeters. Like other gobies, it has a large mouth. Juveniles are usually brown with a series of darker round marks along the flanks, and also have a black mark on their posterior part, which fades as the individual ages. Adults in contrast have a grey to black body and fins and a clearer underside.This freshwater goby can be found throughout the Southwest Indian Ocean. It has two dorsal fins and is distinguished by its rather large head and fusiform body. It can measure between 10 to 25 centimeters. Like other gobies, it has a large mouth. Juveniles are usually brown with a series of darker round marks along the flanks, and also have a black mark on their posterior part, which fades as the individual ages. Adults in contrast have a grey to black body and fins and a clearer underside. 

Habitat and ecology

These freshwater gobies can be found mostly in slow to fast current freshwaters – and occasionally in brackish waters – up to the first waterfalls. They have a preference for clear waters which have sand, gravel or rock substrates. These gobies feed on algae, detritus, worms, gastropods and crustaceans. In order to reproduce, adults migrate to the mouths of rivers. Adult males will fecund the eggs that the female will lay on the rock surfaces. Males are responsible for looking after the eggs until they hatch; a period of 24 to 70 hours. Juvenile larvae will spend 150 to 165 in seawaters before migrating back to freshwaters.

 

Conservation and threats

Although its official conservation status has not been determined in Mauritius, it is considered ‘Critically Endangered’ in Reunion island, where a decline in the population trend has been observed over the last ten years.

A number of threats exist in Mauritius also: habitat fragmentation, decrease in quality of water in downstream areas, poaching and invasive alien species which compete with the goby. The species is also being used as bait by fishermen for fishing activities. It is therefore presumed that this may contribute to the vulnerability of the species. Conservation and restoration actions which focus on reducing habitat fragmentation and improving water quality are recommended.

Did you know?

Although its climbing abilities have not been thoroughly studied, it is expected that this goby has less “power-climbing” abilities than its cousin, Awaous guamensis, as it is found only downstream of major obstacles such as waterfalls.