The oriental weatherloach (Misgurnus anguillicaudatus) is a popular freshwater fish kept by many aquarium enthusiasts, however in the waterways of south eastern Australia it is considered a pest species. Populations of the oriental weatherloach have become established in several NSW rivers.
Weatherloach have an elongate, cylindrical body and are generally a mottled brownish-yellow colour, with a pale underside, numerous black spots on the back and sides, and a prominent black spot at the base of the caudal fin. They can reach a maximum length of 25 cm but in Australia usually grow to only around 20 cm. Weatherloach are sometimes confused with small eels but can be readily identified by the existence of five pairs of barbels around the mouth and a short dorsal fin. The body is covered in mucus, resulting in difficulty when handling this species.
Males can be identified by an enlarged second fin ray, giving a triangular appearance to the pectoral fin. Females display a more rounded pectoral fin.
The oriental weatherloach is a hardy species that can live in a wide range of environmental conditions. The species thrives in water temperatures ranging from
Oriental weatherloach are native to China, Siberia, Korea, Hainan and Japan. They are widely eaten in eastern Asia and have been introduced into Mexico and the Philippines for aquaculture.
This nocturnal bottom dweller is typically found in still waters with sandy or muddy substrates. The weatherloach feeds on algae, aquatic insect larvae, crustaceans and rotifers.
The weatherloach is a multiple spawner, laying 4-8000 eggs per spawning on aquatic vegetation or mud. With a lifespan in captivity of 13+ years, it is possible for one female to lay up to approximately 100,000 eggs in her lifetime. Due to their relatively high fecundity, hardiness and mobility there is a high risk of self sustaining populations becoming established once the weatherloach is introduced into new areas.
After colonising the Ginninderra Creek in the ACT in 1986, the oriental weatherloach spread into tributaries and consequently into NSW waters soon after. Within NSW, populations of this species have been recorded in the Hawkesbury River, Murray River, Murrumbidgee River and Port Hacking catchments, and in tributaries of Lake Eucumbene.
The oriental weatherloach is a popular aquarium species in Australia. It is thought that the discarding of unwanted specimens by aquarists or escapees from ponds were the source of early populations in Australian waterways. It is thought that the spread of this species within both NSW and Australia has been greatly facilitated by illegal use of the species as live bait by anglers. Anglers should note it is illegal to use any live fin fish as bait in NSW freshwaters.
Oriental weatherloach is listed as a Class 1 noxious species in NSW, which prohibits sale and possession of this species, and heavy penalties apply. NSW DPI will continue its ongoing monitoring of coastal and inland rivers. If any new populations of oriental weatherloach are discovered they will continue to be monitored, and where possible, action will be taken to control or remove them.