The kuhli loach (Pangio kuhlii) is an interesting little oddball fish that is a great addition to your aquarium. They look like a little eel and scoot around the tank with this crazy snake-like movement.
It’s so “snake-like” that it actually creeps some people out.
Is it weird that the fact that they freak some people out makes them even cuter to me?
Oh well, moving on…
Kuhli Loach Appearance
Most often, the kuhli loaches you see in the aquarium trade have a striped pattern.
Their bellies are a burnished gold color that may have a pink hue to it. This is broken up along the back with patches of dark brown/black with a thin stripe of the golden color in-between.
They have a tiger stripe sort of look that really is quite eye catching.
Kuhlis aren’t very big, they top out at around 4 inches (10 centimeters) long, definitely not a big bruiser.
In the Wild
Kuhli loaches are scavengers by nature, scouring the bottoms of their waterways, looking for pretty much anything small enough to fit in their mouths: fish eggs, insect larvae, tiny crustaceans, etc.
These loaches are a shoaling fish. So they hang around together in groups for social reasons, but they don’t swim together in a coordinated fashion like a schooling species. They’re often found in groups of a dozen or more.
Because of this shoaling behavior, you should plan on keeping a group of at least five or more.
Native to Indonesia and Malaysia, these fish come from rivers and streams with soft, slightly acidic waters. Since most of the kuhli loaches available in the aquarium trade are wild caught, it’s best to mimic their natural water parameters as much as possible.
Kuhli loaches might look a lot like an eel, but they’re classified as a fish, mainly because of their fins.
True eels don’t have any pelvic fins and their dorsal, anal and caudal fins are fused together, forming a kind of paddle on their back end.
A kuhli loach does have pelvic fins and its dorsal, caudal and anal fins are distinct and separate from each other.
Kuhlis are a so-called “scaleless fish.” They aren’t completely scaleless, but their scales are really small and spread very far apart, leaving their skin exposed.
This makes them more vulnerable because they don’t have a protective layer of tough scales covering their much softer skin.
Pro Tip: Scaleless fish are much more sensitive to salt and medication levels in tank water. What would be a normal dose of medication for most fish can be deadly to a kuhli loach.
Consult a veterinarian that specializes in fish before adding medications to a tank that houses this species.
How to Set Up a Kuhli Loach Tank
Let’s go through what a kuhli loach requires in an aquarium.
This species originates from tropical waters and needs temperatures of 75°-85°F (24°-29°C) in order to thrive.
So you absolutely need to add a heater to your tank in order to maintain a healthy temperature range for them.
Kuhli loaches like to explore any little dark place they can find. Unfortunately, that sometimes means the filter intake.
Some aquarists have gone searching for missing kuhli loaches and found them munching on detritus in the filter. This can injure or even kill the loach, so you should do everything possible to prevent this from happening.
It’s best to cover your intake with a sponge pre-filter to prevent kuhlis, and other little critters, from getting sucked in.
Pre-filter sounds complicated and sophisticated but all it really means is an extra strainer with a sleeve of coarse sponge that goes over it.
The best kind of substrate for these fish is soft sand. Kuhli loaches love to dig around in the substrate, and will even bury themselves below the surface.
These little guys are also a filter feeder. In the wild, they scoop up mouthfuls of sand and sift through it so they can eat things like insect larvae, tiny crustaceans or even fish eggs.
So they’ll really appreciate a sand substrate in their tank since this is a big part of their natural behavior.
Plants and Decor
They are a very shy little fish that likes to hide during the day and then come out at night. They also like to hide together and get in a big pile with each other.
These fish need some dark little hiding spaces like small caves, the underside of driftwood or plant roots (especially plants like Java fern or anubias) or inside decor.
They want a somewhat tight space to hide in so they feel more secure.
Kuhli loaches are shy little critters.
I mean, who can blame them?
They can’t really defend themselves and bigger fish will just suck them up like spaghetti noodles. Hiding is their only means of defense.
They are nocturnal and will not venture out into the bright light. Unfortunately, this makes it really hard to see them because they’re hiding all the time.
If your lights are dimmable, mimicking sunrise and sunset might encourage them to come out and forage.
Also, adding a blue or red night light to your tank will let you see them when the bright lights are off.
Kuhli loaches originate from waterways in Indonesia and Malaysia. Their native streams have a slightly acidic pH and very little hardness.
Unlike a lot of fish in the aquarium trade, these fish are mostly wild caught, not tank bred. So it really is best to give them water conditions that mimic their native waters as much as possible.
- Temperature: 75°-85°F (24°-29°C)
- Ammonia/Nitrite: 0
- Nitrate: >30 ppm
- pH: 5.5-7.0
- GH: 3-5 dGH (50-83 ppm)
- KH: 3-4 dKH (53-71 ppm)
Diet and Feeding
Kuhli loaches are scavenging bottom feeders, which means that they’re not picky eaters and will gladly scarf down just about any kind of food.
If you have other fish in the tank that are messy eaters, the kuhlis will prowl around at night and eat up the leftovers their roommates missed.
But just because kuhli loaches make a great cleanup crew does not mean that you can skip feeding them as well.
The best way to do this is to add a sinking food right when you turn the lights off for the night. Give them a varied diet made up of high quality foods.
Fluval Bug Bites Bottom Feeder Formula provides a really similar diet to what they would get in nature since its main ingredient is insect larvae.
Omega One Shrimp Pellets are another great choice that are made from quality ingredients like whole shrimp and fish.
This is a shoaling species, so plan on keeping them in a group of at least five to keep them happy.
Kuhli loaches are small, super peaceful and delicate when it comes to roughhousing with other fish. So they need to be protected and only housed with other peaceful community fish. Some good tank mates include:
- Neon tetra
- Cardinal tetra
- Blackskirt tetra
- Harlequin rasboras
- Chili rasboras
- Cherry barb
- Celestial pearl danio
- Zebra danio
- Fancy guppy
- Platy fish
- Otocinclus catfish
- Cory catfish (but they’ll compete for food)
- Bristlenose pleco
- Clown pleco
- Nerite snail
- Mystery snail
You could pick a few tank mates from this list, have a vibrant community tank and the kuhli loaches would help keep the tank nice and neat by eating the scraps everyone else misses.
Pro Tip: If you mix in other bottom feeding fish, like corydoras catfish, it’s important to make sure everyone gets enough to eat. When you add food at lights out, put it in several places around the tank to make sure everyone gets an equal shot at grabbing some dinner.
Tank Mates to Avoid
Since kuhlis are so little, and their only defense is to hide, you should avoid any kind of large, aggressive fish.
I would recommend staying away from cichlids (except maybe rams). They just get too large and could easily bully or kill kuhlis.
Even cichlids like angelfish that are often kept with other community fish would be too much.
Monster fish like pacus, shovelnose catfish, redtail catfish or gar would be out of the question.
Goldfish are pretty much eating machines with fins and they would definitely suck up a kuhli loach like a lo mein noodle.
Breeding Kuhli Loaches
Breeding kuhli loaches can be difficult, but there are reports of successful spawning in an aquarium environment.
Your best bet is to move about eight loaches into a 20 gallon (75 liter) tank with no other fish.
The tank should have a sand substrate and be filtered using a basic sponge filter. Make sure to provide lots of plants and hiding places so that the adults are as comfortable as possible.
It’s important to add floating plants with roots that hang down, like dwarf water lettuce, as well as plants that are easy to remove, like Java moss. Loach eggs will get stuck to these after spawning so you can more easily move them to another tank.
Raise the temperature to about 83°F (28°C).
Start to get the adults into spawning condition by feeding them protein rich foods like bloodworms, brine shrimp, mysis shrimp and tubifex worms.
It’s best to do 5% water changes daily. Once it looks like females have begun to get plump with eggs, start to add 1 gallon of cool distilled water when you turn off the lights in the evening. This simulates the evening showers typical of the rainy season.
If all goes well, pairs of fish will start to swim together the next morning. They will dash up to the surface together, wrap around each other and drop back down to the substrate.
As they drop, the female will release eggs and the male will fertilize them. The eggs will sink down and get stuck on the plant roots and moss in the tank.
Remove the plants, and the eggs stuck to them, and place them in another tank so that the fry can be raised in safety.
Are Kuhli Loaches Right for You?
There are some things to consider before you add this species to your tank.
Since they are primarily wild caught fish, it’s best to keep them in water conditions that are close to their native habitat, that means soft, slightly acidic water.
If your water parameters aren’t a good match, this might not be the fish for you.
They are also small, peaceful fish that are vulnerable to attack. They make a great addition to a laid back community tank, but if you have big, mean fish like cichlids, they are not a good fit.
Also, they need a wide variety of hiding spots and so they do best in a heavily planted/decorated tank. If you’re running a wide open, bare bottom setup, these little loaches would not thrive in that environment.
But, if you can provide what they need, kuhli loaches are a great species to keep. They are a nifty little critter that does a great job helping to keep the tank clean, and they don’t add very much bioload.
They’re unique and useful, who doesn’t love that?