Dojo loach or weather loach (lat. Misgurnus anguillicaudatus) is a fish of family Cobitidae, that has been successfully kept in aquaria for many years. Aquarists like the fish for its extraordinary unpretentiousness, peaceful temper and interesting behavior.
Well, this is due to its interesting feature – sensitivity to atmospheric pressure and weather changes.
Before this happens the loach starts demonstrating disquiet behavior, it swims all around the tank and looks out from the water.
People in many countries have noticed this peculiarity (in Japan, for example), they kept the fish as a barometer that predicts weather change.
Using the fish behavior scientists very often find out not only about weather changes, but also about nature disasters that are coming, such as tsunami or earthquakes.
Habitat in the wild
The weather loach is endemic to such areas as Siberia, Sakhalin island, Korea, Japan, China, North Vietnam and possibly Laos (as for the latter we don’t know for sure if the fish used to live there initially or it was brought there).
However, representatives of this kind successfully assimilated to Germany, Spain, Italy, Kazakhstan, Uzbekistan, Turkmenistan, Philippines, USA (including Hawaiian Islands), Canada and Australia.
Such a wide distribution first of all is due to broad commercialisation of the fish in aquarium husbandry, however the fish is also used as food or as a live squid to catch larger fishes.
Its high endurance and adaptability to various conditions, omnivory, high breeding potential and low vulnerability to predators – these are the factors that allowed the fish to spread so widely.
Such expansion of area of the fish distribution is a matter of concern since the fish pushes out local fish species from their waters. Because of this it is prohibited to import the fish into some countries. For example, in England you’ll need a special permission to sale and keep this fish species.
More often you can encounter dojo loach in shallow waters of streams and rivers or in bogs, ponds and other lentic or slowly flawing waters.
The fish prefers thickly planted areas with fallen leaves on the bottom and sandy/muddy bottom substrate. In rivers it prefers muddy places with lots of plants, quite often these are distributaries, bays and dead stream branches.
If there is very little dissolved oxygen in water the fish often swims very close to the water surface, exhales and gasps a new portion of air by making a specific squeak.
Waters purity and depth have seasonal pattern and with some periodicity this fish species can swim into the temporary flooded areas.
During drought season some water dwellers can survive in completely dry ponds and when the water comes back these dwellers get back to life.
This fish has a rare ability to dig itself into mud 1-2 meters deep and hibernate till the time when water gets back to the place again. In general, this loach can live in any kind of lentic waters, even in bogs.
The unique ability of the loach to live without water for a long time is explained by the fact that unlike most of the fishes it can breathe not only using its gills, but also by with its skin and intestinal tract.
Its gut walls have a lot of blood vessels and they perform respiratory function in case when the fish organism feels the lack of oxygen.
When gasping air the loach takes it through the intestinal tract and then exhales through the spout-hole (this process explains the squeak sound loaches make when you take them out of water).
Some fishermen say that large species as well as eels can crawl from one pond to another (closely located) in the early morning when it is dewy. There are some records about species who survived quite long stay in wet sand or mud without any water.
The size is up to 12 inches (30.5 cm). Pay attention, that this is the size that makes it different from another tank fish – kuhli loach.
Both fishes have similar structure (but kuhli has very specific coloring) and at that the fishes have very different size.
The lifespan depends on the water temperature where it dwells. It prefers cool water with the temperature lower, than that for tropical fishes.
Provided with such water temperature the loach will live up to 10 years, if the water is warmer the lifespan gets shorter and it is about 4-5 years.
Loaches have elongated body covered with small but clearly seen scales. The mouth is edged with 10-12 barbels; the tail fin is rounded. Its infraorbital spine is hidden deep under the skin and it doesn’t function.
The fish has small yellow or brown eyes. The color intensity depends on its living environment. The body is light olive, greenish colored with lots of small spots on it, but you can also encounter white and golden species.
There is a golden variety of the fish which is usually sold as “golden dojo”. It is partially an albino form, the body is pinkish with yellow tint, the eyes are dark colored.
Difficulties in keeping
This is one of the most undemanding tank fishes, which is perfect for beginners and those who can’t spend much time on taking care of a tank and its dwellers.
But, keep in mind that to keep this loach successfully you’ll need quite cool water in the tank.
Care and keeping in a tank
|Scientific Name||Misgurnus anguillicaudatus|
|Common Names||Dojo loach, dojo fish, pond loach, oriental loach, Japanese weather loach, weather loach, oriental weatherfish, chinese weatherfish, golden dojo|
|Tank size||40 gallons and more|
|Diet||Omnivorous bottom feeder|
|Temperature||68-72 °F, 20-23 °C|
|Size||up to 12 inches (30.5 cm)|
|Lifespan||up to 10 years|
This fish isn’t difficult in terms of keeping, but you have to provide it with soft and small grained bottom substrate.
Large stones with sharp edges can damage delicate skin of the loach and the fish will be stressed if it doesn’t have a chance to dig itself into the bottom substrate.
Perfect bottom substrate is small grained sand. Large smooth snags and stones as well as other various tank decorations will do for the fish, since the more shelters are in the tank the better.
Tank lighting should be moderate, it is desirable to shadow the tank bottom by putting floating plants into the tank.
If you want, you can add some fallen leaves to create conditions that are close to the fish habitat.
Make sure that there are safety caps on the filters and the tank is covered with a lid, since most of species tend to jump out of the tank, especially at the beginning.
But even if you have found the loach on the floor, put it back into the tank, because there is a chance it will be fine quite quickly.
Despite its high adaptability to various conditions, it is not recommended to put this fish species directly into a new tank without a settled biotope.
Proper tank water parameters are the following: pH 6.0-8.0, DH – 1-12.
As for the temperature, in general this species will stand the range 5—25 °C, however the recommended tank water temperature is (68-72°F, 20-23°C).
The loach can live at higher temperature, but it shortens its lifespan as well as the fish is more prone to various infections at such conditions.
It is important to keep in mind that this isn’t a tropical fish and it shouldn’t be kept at tank conditions which are extreme and unusual to it.
Dojo fish is omnivorous; insects larvae, small crustaceans and others are the basis of the diet. In a tank you can feed the fish with artificial food that sinks out on a tank bottom. However, the diet should include frozen or live food (daphnia, bloodworm, worms).
Pond loach gets very attached to its owner and they like when he strokes them or feeds them from his hands.
Compatibility and tank mates
The fish is undemanding in terms of keeping in a tank; it is active and peaceful, but it may prey on juveniles or eat fish eggs.
You can keep just one fish in a tank, but they feel more comfortable in a company of its kind.
Perfect tank mates are goldfish. They require the same tank water temperature, they aren’t rivals in terms of food and they swim in different water layers.
Loaches eagerly eat food leftovers that goldfish leave, which decreases the level of ammonia and nitrates content in the tank.
Males have longer and thicker first ray of their pectoral fin; they have a nub formed by fatty tissue on the body sides behind the dorsal.
Information about breeding in captivity is quite fragmented and limited. Presumably in farm hatcheries they use hormone injections for this purpose, because this species are highly demanded on the market (aquarists, food industry and scientists – they all need it).
In the wild spawning occurs as follows: the male during its mating display hugs the female and fertilizes the eggs she lays. Then the eggs sink out on the substrate.
The female fish lays about 100-150 eggs among algae. The eggs are 1,7-1,9 mm in diameter, not very sticky, they have light brownish color.
At water temperature 14-16 °C the egg stage lasts for about 4 days. Once the larvae hatches, they have additional respiratory organs represented by external gills.
Except this, dense network of blood vessels in large pectoral fins and later those in intestinal tract of the larvae also perform additional respiratory function.
Being about 8 mm long on the 12th day of their life the larvae starts to feed. They look for food by means of special sensory organs located around their mouth and on the barbels (they develop very early).
At the age of 26 days old their external gills get completely reduced. Juvenile stage starts when the larvae becomes 30 mm long.
Sergey is a founder and author of Meethepet.com. He’s been fond of aquarium husbandry since his early childhood.
His favorite aquariums are biotopes (Amazon River), with Echinodorus and Angelfish. However, through the years he’s had experience of keeping almost all types of freshwater fish and shrimps.