Weather Loach (Misgurnus anguillicaudatus)

Weather Loach (Misgurnus anguillicaudatus) by Noel Burkhead Public domain 06/04/10
Weather Loach (Misgurnus anguillicaudatus) photo by Noel Burkhead

The Weather Loach (Misgurnus anguillicaudatus), also known as the Dojo Loach, is a freshwater fish in the loach family Cobitidae. They are native to Asia but are also popular as an aquarium fish. The name Weather Loach is shared with several other Cobitinae, including the other members of the genus Misgurnus and the spotted weather loach (Cobitis taenia, commonly known as Spined Loach). The name 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 and liable to jump. It is not unusual for Weather Loach to jump out of the tank or pond during a storm.

Like many other loaches, they are slender and eel-like. They can vary in color 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 defense unlike the other loaches who use the spines beneath the eyes.

They can grow up to 12 inches (30.5cm) long. Weather Loach are bottom-dwelling scavengers, feeding mainly on organic material such as algae. Weather 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 also survive small periods of not being in the water. They are very hardy fish that can survive in poor water quality.

Although often sold as a tropical fish, the Weather Loach can thrive at lower temperatures. In the wild it inhabits areas with a temperature range of 5°C - 25°C and has been known to tolerate temperatures as low as 2°C making them suitable for the garden pond in many areas. The usual tropical temperature will result in a significantly reduced lifespan (from an average 10 years to four or less).

Sometimes this fish (especially the golden variety) is mistaken for the kuhli loach. The kuhli likes warm tropical temperatures, will tolerate more acidic conditions, and matures at a much smaller four inches. Very different fish, but may resemble each other while young, and at the usual age and size of what most fish stores market.

The European Weather Loach (Misgurnis fossilis) comes under The Prohibition of Keeping or Release of Live Fish (Specified Species) (Amendment) (England) Order 2003, see the ILFA Leaflet for further information.

Weather 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 have, however, been known to attack very small fish in smaller aquariums. They get along better with goldfish.

In the Aquarium

There are other varieties bred from captivity like the gold strain and the peppered strain (not to be confused with the pepper loach).

The loaches will be more active given more space and greater numbers. Solitary weather 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 Weather Loach doesn't show up for roll call one day. Weather 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 weather 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 weather 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 Weather 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.