The kuhli loach (Pangio kuhlii also Acanthophthalmus kuhli) is one of the most interesting freshwater aquarium fishes. It is an eel-like fish that usually has alternating light and dark bands on its scaleless body (although there is a black variety).
Kuhli loaches are my favorite aquarium fish because they are so interesting fish to watch. They look more like snakes than fish, and you will often find them hanging from plants and other objects in the tank.
Their mouth has barbels and faces downward, which means they feed from the bottom of the aquarium. Kuhli loaches reach an adult size of between 3-4 inches (7.5-10 cm) in length. Kuhli loaches belong to the family Cobitidae.
They are from Indonesia, Malaysia, Borneo, Java, and Singapore.
You'll often see several different species commonly called "kuhli loach" for sale at pet stores. These fish all look similar and have similar care requirements.
Kuhli loaches are nocturnal fish that spend most of the day hiding under plants or rocks. They are bottom dwellers that spend most of their time on the bottom layers of the aquarium. They often burrow right into the gravel. Make sure that the substrate in your kuhli tank doesn't have sharp edges. Sand is best, but round gravel will also work.
It is best to provide caves in their tank for them to hide in during the day. Keep your kuhli tank heavily planted as well. In fact, if you provide your kuhli loaches with a cave to hide in you are more likely to see them. This is because they feel safer knowing the cave is there to retreat to if they need to. I often see mine hanging from the plants and out in the open even during the daytime.
Because of their nocturnal habits, you should feed them at night. Don't turn on the aquarium lights - just put a little food in for the kuhli loaches to eat at night, although you will often see them eating during the daytime as well.
Kuhlis like to congregate in groups. You should keep at least three kuhli loaches together in your tank and preferably a few more if you have the room. Solitary kuhlis are not happy and don't thrive. They are peaceful fish that should only be kept with other peaceful fish.
They are omnivores that eat both plant and animal based foods. Because kuhli loaches are bottom feeders it is best to feed them sinking food. They prefer live or frozen foods, but will accept most foods that are offered.
I have eight kuhli loaches in my tank. They usually spend most of their time in a cave in their aquarium. But when I give them a food they particularly enjoy, such as live or frozen brine shrimp or mysis shrimp, all eight of them will leave the cave or whatever plant they are hiding in to come out to eat. Feed your kuhlis something they really enjoy and you'll see more of them.
Kuhlis aren't real picky about their water parameters, but they prefer soft, slightly acidic water (pH 6.7-7.0) and a temperature range between 75-86°F (24-30 °C).
Kuhli loaches can live for 10 years or more if you keep their water quality good by doing routine partial water changes. Just be careful not to injure them with the gravel siphon if they have burrowed into the substrate.
They are egglaying fish, but rarely spawn in the aquarium. When they do spawn they scatter large green eggs among the aquarium plants. Females are fuller bodied than the males when they are filled with eggs, otherwise males and females look very similar. Kuhli loaches will sometimes spawn in the aquarium if you have several kuhli loaches together and if you have lots of hiding places, like caves. Sometimes aquarists find that their kuhli loaches have spawned underneath the undergravel filter.
No one seems to be certain what water parameters and conditions induce kuhli loaches to spawn, however, keeping them in water conditions similar to their natural habitat is probably most likely to induce spawning, as well as having lots of hiding places for them.