The Ultimate Guide to Breeding Kuhli Loaches

Breeding Kuhli Loaches is no easy task, but if it’s something you want to try then read on.

You’ll find everything you need to know, whether you’re hoping to set up your main tank for breeding or whether you want to use a separate breeding tank.

Is it hard to breed Kuhli Loaches?

It is very difficult to deliberately breed Kuhli Loaches. Water conditions must be perfect, and you’ll need to have your tank set up just right for Kuhlis to spawn. You’ll then need to be prepared to care for the eggs so the adult Kuhli Loaches don’t eat them.

Most beginners and amateur fishkeepers find it very difficult and even impossible to breed Kuhli Loaches deliberately.

Despite this, some have reported breeding by accident. This happens when a well-established and well-cared-for tank provides just the right conditions for breeding.

However, trying to artificially recreate those conditions can be a frustrating experience. Sometimes it’s best to let nature take its course. 

If you’re patient enough to try, here are a couple of challenges to be aware of first.

Kuhli Loaches will eat their own eggs

Kuhli Loaches are scavengers who eat pretty much anything they find on the tank floor. This includes their own eggs.

Kuhli Loach eggs float when they’re first spawned and fertilized. The adults will eat any that then fall to the bottom instead of sticking to plants.

There’s a chance the eggs may go unnoticed if you have a heavily planted tank and they land in the roots of your plants. However, that’s where Kuhlis like to hang out anyway so they’re unlikely to be around for long.

Other fish may eat them too. Fish eggs are full of protein and super tasty, judging by the way they get munched down in a community tank.

If you can get to them first, it’s possible to separate them from the adult fish in the tank. More on how to do this below.

Kuhli Loaches are hard to catch

Using a breeding tank is a good way of increasing the chances of successfully breeding baby Kuhli Loaches.

However, catching your Kuhlis is no easy task! They’re naturally shy and like to hide under plant roots, rocks, and whatever other shelter they can find.

If you do manage to flush them out of their hiding places, they’re so fast and nimble that the odds of catching them in a net are pretty slim.

The pet store staff obviously have to do this when they sell you your Kuhli Loaches, but they’ve had lots of practice! They’re usually trying to net a few Loaches from a tank containing dozens, so the numbers are on their side.

There’s also a difference between catching Loaches in a bare tank with little substrate and plants, and successfully netting the ones living in your own tank.

Ideally, your Kuhli Loaches will be in a tank with plenty of hiding spaces and a lot of plant roots to hide in. It’s hard to net them without kicking up all the debris on the tank floor and uprooting your plants.

However, there are ways of catching them without chasing them with a net, which is just stressful for both of you. Read on to find out more!

How to tell if your Kuhli Loach is pregnant

Kuhli Loaches keep their eggs for around two weeks before spawning, but don’t technically become ‘pregnant’.

A female carrying eggs is ‘gravid’ whereas only live-birthing fish can really be said to be pregnant.

A healthy Kuhli Loach should look plump all through her body, but if there is more of a lump in the center of her body she could be egg-laden.

You’ll be able to see the eggs through her skin on the underside of her body under bright light. However, Kuhli Loaches hate bright light, so good luck persuading them to keep still long enough to check!

How to breed Kuhli Loaches in captivity

If you’re determined to try to breed Kuhli Loaches, there are two ways to go about it.

Firstly, you can encourage breeding in your existing tank. This is probably the more difficult way to go about it, and you’ll need to have a second tank set up to keep the eggs and the babies from the adults.

If not, your fry will be eaten, even if the eggs are around long enough to hatch.

Secondly, you can set up a breeding tank. This will give you a better chance of success, although the conditions in both tanks will need to be perfect.

It’s up to you whether you want to move the eggs to another tank or move the adult fish to another tank to stop the eggs from being eaten. Either way, both tanks should ideally have the same water conditions.

To achieve this, the second tank should be set up using water from the main tank to match as closely as possible. Using a sponge filter from the main tank will help, as the beneficial bacteria can then be moved over to the new tank.

Breeding in your main tank

Firstly, you’ll need to set up your Kuhli Loach tank for optimal breeding conditions:

1. Plants

Having live plants is a must. Kuhlis won’t breed if they feel stressed, and plants are a good way to give them shelter from the bright tank lights.

Plants keep the tank water clean, firstly by consuming CO2 and releasing oxygen into the water. Some, like Java Moss, trap floating debris like uneaten food and fish waste.

Plants with broad leaves like Amazon swords are perfect. They’ll break up the light from above and when eggs are released into the tank, they’ll stick to the leaves far up out of reach of the adults.

Plants with complex root structures like anubias are great as well. My Kuhli Loaches love to hang out in the roots of my anubias plants.

2. Substrate

The best substrate for Kuhli Loaches is usually sand. They prefer sand to gravel because they sift sand through their mouths and gills to filter out food particles.

However, pea gravel is also good as a substrate for breeding Kuhlis. This fine gravel allows eggs to mix in unnoticed, so there’s more chance of the odd one avoiding being eaten.

If eggs do make it to the hatching stage rather than becoming lunch, then both pea gravel and sand give fry somewhere to burrow and hide from the adults. Yes, Kuhli Loaches will eat their babies!

3. Leaf litter

You can also add a layer of leaf litter on top of your substrate. Indian almond leaves are a great addition, as they not only provide more cover for your fry, but there are other benefits too.

The bi-products of the leaves’ slow decomposition process can become a food source as the fry start to grow. They also release tannins into the water which naturally lower the pH to a level that encourages breeding.

Those tannins will start to stain the water, so be aware of this if a crystal clear tank is a deal-breaker for you.

4. pH

Kuhli Loaches usually like pH between 5.5 and 6.5, and as mentioned above they’re most likely to breed in this slightly acidic water.

As well as using tannins from your leaf litter, there are a number of other ways to produce these conditions. Driftwood, peat moss, and peat pellets will also release tannins that will keep pH in the slightly acidic range.

The most important thing to note is not to artificially lower pH by using chemicals. This doesn’t address the cause of the high pH, meaning your levels will fluctuate as you add more chemical solutions.

Your pH will simply return to its alkaline state until you add more chemicals, and the cycle will continue. This fluctuation is stressful for fish and can lead to health problems. It certainly won’t encourage them to breed, as they’ll only do so when they’re happy and healthy.

If your tank has a high pH, it’s important to understand why. That way, you can adjust the setup of your tank before adding fish, rather than trying to treat the symptoms later.

5. Spawning mops

Spawning mops are one artificial addition that is great for encouraging your Kuhli Loaches to breed. 

The strands of the mop are great for catching the floating eggs, and provide thick cover for the fry to hide in when they hatch.

Spawning mops are great if you don’t have live plants, or if you just want to add another place for your eggs to stick until hatching.

They’re also easier to remove from the tank than live plants, which often have complex root systems. These can be damaged during removal, as well as uprooting other plants and otherwise disturbing what lurks in the substrate.

The other advantage of using spawning mops over live plants is that they don’t require any light or fertilizer. You’ll want to move plants with eggs attached to a new tank so the adults don’t eat the eggs, but if your other tank doesn’t have the right conditions, the plants will die.

No such worry with a spawning mop – simply move it to a nice, dark tank and let the eggs hatch in their own time.

They’re not easy to find online, but Aquarium Co-Op have written this handy guide to making your own spawning mops.

6. Dim lights

Kuhli Loaches are mostly nocturnal fish who shy away from bright lights.

As well as using lots of plant cover to provide shade and hiding places like rocks & caves, you can use dim lights in your tank to make the Kuhlis feel more comfortable.

Happy Loaches are more likely to spawn.  You’ll have a much lower chance of success if they’re stressed because of water conditions or bright lights hurting their sensitive eyes.

Look for a dimmable light like this excellent Hygger 9W Full Spectrum Aquarium Light. This model has a timer and is adjustable down to a very low light setting:

7. Surface agitation

Have a sponge filter flowing constantly and keep the water level low enough for the falling water to disturb the surface.

Surface agitation triggers breeding behavior – you can also use an air stone to achieve a similar result.

Using a breeding tank

If you don’t like the idea of breeding in your main tank, you can set up a breeding tank.

This allows you to move the adults into an environment specifically set up for breeding. It allows you to set up your main tank however you want without working to these strict conditions.

What size tank can I use for breeding Kuhli Loaches?

Ordinarily, you’ll need a 20-gallon tank for Kuhli Loaches. However, as it won’t be a permanent home, a breeding tank can be smaller.

Try to give them as much room as possible but don’t worry if they have to spend a little time in a 10-gallon, for example.

Kuhli Loach breeding tank setup

The ideal setup for your breeding tank will be similar to the description above where we looked at how to set up your main tank for breeding.

You’ll need plants for the eggs to stick to, especially floating plants which give the eggs more chance to avoid being eaten.

Sand substrate or pea gravel is best, so the Kuhlis are less likely to discover the eggs as they become buried. When they hatch, the fry will have somewhere to burrow.

Leaf litter also provides a good hiding spot. Indian almond leaves are a great choice as the tannins that leak into the water naturally lower pH and trigger spawning. pH should be around 5.5-6.5 for optimum breeding conditions.

Again, dim tank lights or a dark tank that’s only lit by the ambient light in the room would be ideal.

How to breed Kuhli Loaches in a breeding tank

First, you’ll need to move the group of adults into the breeding tank. This sounds easy, but catching the fast and elusive Kuhli Loaches won’t be!

Rather than stressing them out by chasing them with a net, you can set a trap that they’ll simply wander into of their own free will. This also avoids stirring up the substrate in your tank or accidentally uprooting your plants.

If you have cave decorations, you can use these to tempt your Kuhlis. For a more effective trap, a piece of PVC pipe roughly 1.5 inches in diameter is perfect.

Cut the pipe to between 6-12 inches in length, and block one end with anything aquarium safe (filter floss or sponge is ideal).

Place the pipe in your tank and weigh it down with a stone or other decoration. Then remove any other large rocks or hiding places so your Kuhli Loaches have fewer options for shelter.

Eventually, they’ll swim inside and you can simply place your hand over the open end of the pipe and quickly transfer the Loaches that are caught inside.

How to trigger spawning behavior in Kuhli Loaches

1. Increase temperature

Gradually increase the temperature inside the breeding tank to around 82-85°F (27.5-29°C). 

Don’t do this until the Loaches are in, as they’ll need to get used to the new temperature compared to the old tank.

Higher temperatures in their natural environment are a signal to Kuhlis that it’s time to breed. By increasing the temperature, you’ll trigger their natural instinct to spawn.

2. Feed the right food

A high protein diet gives the Kuhli Loaches energy which helps with spawning. Feed with live foods such as bloodworms 4-5 times per day.

3. Water changes

Remember that water quality is crucial and more food = more waste, so change 10% of the water daily to avoid ammonia spikes.

4. Check the weather!

Believe it or not, Kuhli Loaches are extremely sensitive animals. In the wild they’ll spawn when a weather front comes in, so if possible you’ll need to watch out for this.

5. Perform a bigger water change

Just before this weather front is due, perform a large water change. If you normally change 10-20%, do 50%. 

6. Spray cold water onto the surface

Rainwater is good for this as it won’t contaminate the tank like tap water does. This can trigger spawning as it mimics the weather conditions that happen in the wild during spawning.

Kuhli Loach spawning behavior

If you’ve kept Kuhli Loaches, you’ll recognize the ‘Kuhli Loach dance’. They basically get the zoomies and dart all around the tank at super speed.

When they’re about to spawn, you’ll see them doing this in the early morning. The giveaway is that they’re doing it in pairs because the male needs to follow the female so he can fertilize the eggs.

It’s unusual to see Kuhlis swimming at the surface, but they’ll swim along the top of the water together when they’re about to spawn. Then, they’ll wind their bodies around each other as they fall to the bottom.

This is when eggs are released, and fertilized by the male Kuhli Loach.

What to do after your Kuhli Loaches have spawned

Once the female Kuhli has released her eggs, remove the adults from the breeding tank before they get a chance to eat them.

The bright green eggs will float at first and will attach to the roots of floating plants and leaves of others. 

Any eggs that fall to the bottom of the tank are in danger of being eaten by the adults if you don’t remove them in time, so keep a close watch!

The eggs only take 24 hours to hatch, then you’ll have potentially hundreds of fry.

How many babies do Kuhli Loaches have?

Even though the female Kuhli Loach can lay hundreds of eggs, they won’t all hatch and not all the fry will survive.

Water parameters, temperature, food sources and many other factors will decide how many make it past the first few days. From up to 400 eggs, between 10 and 50 healthy baby Kuhli Loaches would be a success.

Until now we’ve talked about the importance of slightly acidic water to help your Kuhli Loaches breed. Water quality is more important than a specific pH once the fry have hatched, but don’t vacuum your gravel.

A small buildup of detritus containing leftover food and protozoa (single-celled organisms) provides a food source for the fry during the first week. 

You can supplement this with specialist fry foods like Sera Micron Nature, which is made of tiny food particles that mimic plankton:

As your fry grow, introduce live foods like bloodworms, brine shrimp or daphnia after a week or two.

Finally, perform daily water changes. Fry are sensitive to water quality so change around 5-10% of the tank water and remove any uneaten food. Of course, be careful that you don’t suck up any of the babies as you siphon out the old water.

Summary

All the above will give your Kuhli Loaches the best chance of producing eggs, and give the babies that hatch the best chance of survival.

If you’re lucky enough to have successfully bred Kuhli Loaches and you actually have too many, you can sell or donate the juveniles to your local fish store. When they are around 2 inches in length or 5-6 months old, they’re saleable.

If you manage to purposely breed Kuhli Loaches, either in your main tank or in a separate breeding tank, you’ve achieved something many of us have failed to do. Congratulations!

In the meantime, if you have any other questions about these wonderful fish, you’ll find everything you could possibly need to know in this Kuhli Loach care guide.