The pond loach, dojo loach (ドジョウ dojō?), or oriental/Japanese weather loach (Misgurnus anguillicaudatus), is a freshwater fish in the loach family Cobitidae. They are native to East Asia but are also popular as an aquarium fish and introduced elsewhere in Asia and to Europe and North America. The alternate name weather loach is shared with several other Cobitidae, including the other members of the genus Misgurnus and the spotted weather loach (Cobitis taenia, commonly known as spined loach). This term comes from their ability to detect changes in barometric pressure and react with frantic swimming or standing on end. This is because before a storm the barometric pressure changes, and this is known to make these fish more active. The pond loach also comes in a variety of colors, such as pink, orange, and gray.
Like many other loaches, pond loaches are slender and eel-like. They can vary in colour from yellow to olive green, to a common light brown or grey with lighter undersides. The mouth of the loach is surrounded by three sets of barbels. It uses them to sift through silt or pebbles to find food. It also uses them to dig under gravel and sand to conceal itself out of nervousness or defence unlike the other loaches who use the spines beneath the eyes.
They can grow up to 12 inches (30.5 cm) long. The fish are bottom-dwelling scavengers, feeding mainly on organic material such as algae. Pond loaches are omnivorous and may also feed on tubifex worms and other small aquatic organisms. By producing a layer of mucus to keep themselves damp they can survive short periods of desiccation. They are very hardy fish that can live in poor quality water.
In the aquarium
Pond loaches are active, peaceful, and hardy fish that are sometimes used as starter fish in an aquarium. They can be "friendly" towards humans, allowing physical contact and hand feeding. They are extremely peaceful. They get along better with goldfish.
The loaches will be more active given more space and greater numbers. Solitary pond loaches tend to spend much of their time hiding. They will spend a lot of time hiding or staying still, but should be given a place to stay which will have cover and shade. Tank decorations that they can swim through and driftwood both work great for this. Due to their jumping ability the average cover should be enhanced with tape or other barriers. However, if you happen to find your loach black and dry on the floor one morning, try placing it back in the aquarium. Usually it will revive and swim away and make a full recovery. In some cases, it has been reported that they can live up to three days out of a tank. Also, they may even travel up tubes and take up residence in filters, so check there if your pond loach does not show up for roll call one day. Pond loaches enjoy digging and burrowing themselves in the substrate of their tank, so make sure that your substrate is fine enough for them to dig in. If you keep live plants in your tank, they will be uprooted by the loaches, so it is a good idea to weight your plants. The pond loach is also peculiar in that it will sometimes bury itself in the substrate during times of stress. This often surprises new owners, as the fish will "disappear" shortly after introduction to the tank only to "reappear" later.
Because of their appetite for snails, these loaches can help alleviate snail infestations in tropical fish tanks, though many have reported that while pond loaches do eat snails, they do not eat them at a fast enough rate to deal with an infestation.
The fish prefer a pH of 6.5-8.0 but will tolerate far more acidic conditions even for extended amounts of time with little negative reaction. This makes the pond loach a great choice for first-time aquariums and for those who want a fish tank but do not want the intense, daily attention other fish require. This fish should be kept in groups of at least 3, as they like to be in physical contact with each other and feel each other with their barbels when they rest.
One trait which distinguishes the pond loach from most other tropical fish commonly seen at aquarium speciality shops and pet stores is the fact that they thrive at room temperature (68-72°F, 20-23°C) and can do well even at temperatures as low as the upper 50's Fahrenheit (13-15° Celsius). The usual tropical temperature will result in a significantly reduced lifespan (from an average 10 years to four or less). Purchasers often presume when buying tropical freshwater fish that all species will thrive in the (typical for home freshwater aquarium installations) 76-82 °F / 24-28 °C range; this presumption is incorrect in the case of the pond loach.
There are other varieties bred from captivity like the gold strain and the peppered strain (not to be confused with the pepper loach). Sometimes the pond loach (especially the golden variety) is mistaken for the kuhli loach. The kuhli, however, likes warm tropical temperatures, will tolerate more acidic conditions, and matures at a much smaller four inches (10 cm). Although these two species have numerous differentiating traits, individual kuhli and pond loaches may resemble each other while young and at the usual age and size of what most fish stores market.
The pond loach is a common food fish in East Asia, raised on a large scale in fish farming.
- "Misgurnus anguillicaudatus". Integrated Taxonomic Information System. Retrieved 30 January 2006.
- Froese, Rainer and Pauly, Daniel, eds. (2005). "Misgurnus anguillicaudatus" in FishBase. 10 2005 version.
- How to Keep Your New Weather Loach
- "New Invasive Fish Spreads Through The Ebro Delta". Science News (Science Daily). 2009-01-20. Retrieved 2009-01-20.
- Franch, Nati; Miguel Clavero, Montse Garrido, Norbert Gaya, Veronica Lopez, Quim Pou-Rovira and Josep Maria Queral (2008). "On the establishment and range expansion of oriental weatherfish (Misgurnus anguillicaudatus) in NE Iberian Peninsula". Biological Invasions 10 (8): 1327. doi:10.1007/s10530-007-9207-9.