Photo credit: © Manoel Jr./Flickr
Report this Species!
If you believe you have found this species anywhere in Pennsylvania, please report your findings to iMapInvasives by submitting an observation record.
Species at a Glance
The oriental weatherfish, also called the dojo and Chinese loach, is a small eel-like fish that gets its name from its ability to forecast the weather. It is sensitive to changes in barometric pressure, so increases in activity and swimming in fast circles can indicate that major weather changes are imminent. This species is also popular in the aquarium trade because it is hardy and has a voracious appetite that can help keep tanks clean. Unfortunately, the release of this species into natural waterways has caused negative impacts to water quality, native species, and the food web.
The oriental weatherfish has a long, cylindrical, eel-like body with greenish grey-brown marble markings on the dorsal side, and pale silver sides and underbelly. Many specimens have a large pigmented spot located above the base of the caudal fin. The mouth is small and narrow with thick, fleshy lips surrounded by ten barbels. The lateral line is short and doesn’t extend past the pectoral fin. The pectoral fin has a stout spine, and the caudal fin is rounded. Average size is up to 28 cm (11 in) long. This species exhibits sexual size dimorphism, with the average length of the female being considerably larger than that of the males.
Because of its eel-like body, the oriental weatherfish may be confused with species of lamprey; however, lamprey are typically thinner and don’t have the characteristic barbels on the mouth.
This species is very hardy and can survive a wide range of temperatures and environmental conditions. It is typically found in slow or still waters with muddy or silty bottoms abundant with aquatic plants. It feeds on bottom-dwelling animals, insect larvae, snails, and worms. The oriental weatherfish can breathe atmospheric oxygen by using its intestine as an accessory respiratory organ, allowing it to live in oxygen-poor waters and to bury itself in soft substrates to survive long droughts.
Used as bait, and commonly sold in the aquarium trade, the oriental weatherfish can be released when aquariums are dumped, or when bait buckets are emptied. Their use as a food fish is also linked with their purposeful introduction into the wild to create harvestable populations.
Native to Eastern Asia, the Oriental weatherfish was most likely introduced to natural waters of the United States by fish farm and aquarium escapes. It has not yet been introduced into Pennsylvania, but is established in drainages in New York and New Jersey.
Note: Distribution data for this species may have changed since the publication of Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015), the source of information for this description.
Oriental weatherfish can negatively impact native species by predation and competition for food, habitat, and spawning sites. They can also increase turbidity and nitrogen levels in standing water, which can negatively impact water quality
Information for this species profile comes from Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015).