Loach

Many species of loach are popular in the aquarium trade.

The loach superfamily of fishes consists of over 1200 species, most of which are distributed in central and southern Asia. Some species are also found in Europe and Africa. They are known for their bottom-feeding and the barbels found close to their mouths. Loach fish prefer ponds and streams, either stagnant or fast-moving.

4 Incredible Loach Facts!

• Loach fishes often have sharp barbs below their eyes for defensive purposes.
• There are over 1200 species in the superfamily Cobitoidea.
• Most species have barbels around their mouths, which they use to detect food.
• The yoyo loach is actually named after the black pattern on its side, which looks like it spells out “yoyo.”

Loach Classification and Scientific Name

The superfamily Cobitoidea includes an enormous amount of species. There are 9 families within the superfamily, and about 107 genera. Cobitoidea comes from a term used by Aristotle, many centuries before modern taxonomy. Aristotle used the word cobitis to refer to any small fish that buries in the sediment.

Loach Species

With over 1200 species in the superfamily, Cobitoidea is one of the largest in the fish world. A few popular species include:

• Clown Loach: These aquarium fish range from about 15-20cm in length and are largely diurnal, which is unusual for a species of loach. They are pale orange with dark black patches, given them their “clown” namesake. Females are larger than males.
• Kuhli Loach: Another popular aquarium fish, Kuhli or “coolie” loaches are long and eel-like with dark bands covering its body. As adults, they are about 4 inches long. They can live to be up to 10 years old and are native to southeast Asia.
• Yoyo Loach: Yoyo, or Pakistani loaches, are interestingly colored fish. They are white with thin black, curvy lines around their bodies that mark out “y” and “o” shapes, giving them their names. They also tend to bob up and down with the water levels, much like the popular “yoyo” children’s toy. These fish prefer slow-moving water.
• Hillstream or Butterfly Loach: Native to fast-moving bodies of freshwater in Asia, these fish is a taupe-colored species covered in intricate black markings. Hillstream loaches are also known as the Chinese Butterfly Loach. They have wide fins, which gives them their “butterfly” namesake and are a docile species that prefer at least 3 tankmates of the same species.
• Java Loach: These fish are very similar to the kuhli loach, but do not possess the same black markings on their bodies. They are elongated and a dark to pale brown color depending on their environment. These fish are 3in long when they are fully grown.
• Sumo Loach: Native to Myanmar, the colorful fish is a small, elongated species with bands of color along its sides. They have a patterned dorsal fin. The color of the fish can change, though it is not apparent what causes those changes.
• Golden Zebra Loach: Golden zebra loaches can be up to 5in long when fully grown. This fish is black and gold and grows a bold pattern as it ages. These fish sometimes nibble on softer plants.
• Rosy Loach: These are some of the smallest species, only reaching about 1.2in in length. They are also a rare breed that does nicely in micro-aquariums.

Loach Appearance

The loach fish’s appearance varies wildly depending on the species. Most of them are small and elongated, with barbels around their mouths and sharp spines beneath their eyes, which they use for defense. Their spines are small and flexible. These fish can grow anywhere from 1in to 8in in length.

These fish can be thin and small, like the rosy loach species. They can also be wide and large, like the popular butterfly loaches.

Some of them, like the clown, yoyo, and hillstream loach, have beautiful dark patterns on their scales.

Loach Distribution, Population, and Habitat

Almost all of the existing species are native to Asia, where they prefer freshwater streams. Most species of these fish can be found high on the mountaintops, where the streams are swift and cold. However, there are any lowland species of them as well. Some species, like the butterfly loach, prefer fast-moving streams. Other species like ponds and other low-oxygen bodies of water. Some have even lost their ability to see and live in the dark ponds and rivers of caves.

These fish do not form large schools, but they do appreciate the company of other fish of the same species. This is also true in captivity, as they will become hostile towards other fish species if they are the only loach in the tank.

One species of these fish is found in Africa, and three species have been found in Europe.

Loach Predators and Prey

These fish prey on the various worms and larvae that fall close to the bottom of their habitats. They are omnivorous and bottom-feeders, which means they consume plant substrate as well. These fish in captivity should be fed a mixture of live food and fish flakes.

Humans consume these fish, specifically in east and southeast Asia. Larger fish may also prey on the fish found in their environment.

Loach Reproduction and Lifespan

Most loach species are extremely difficult to breed in captivity, and new loaches must be caught in the wild.

More of these fish in an environment will encourage breeding, as they are communal spawners. Females will lay their eggs on the undersides of leaves. Within 24 hours, the young will hatch from those eggs and swim away. Baby fish are called “fry.” Most eat soft plants or small invertebrates as their first meal.

Loach in Fishing and Cooking

The Japanese have been eating these fish for many centuries, and they are known as “dojo” in Japan. Most frequently they are seared or cooked in soup. They have soft meat and bones and are often served at the beginning of summer.

Loach Population

With over 1200 species, these fish live in a wide variety of habitats and are at various risks of extinction. Most species are of Least Concern, but some are endangered. Overall, populations are declining slightly. This may be due to overfishing, or habitat loss.

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