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Chromobotia macracanthus

(Bleeker 1852)

 All text and photos by Ola Åhlander unless otherwise stated

Translation to English by Paul Stanton



Clown loaches are one of the most popular aquarium fishes kept and has been so for a long time, but surprisingly very little is known about them and their biology. It is mainly how they reproduce that is unknown to us. Here I will go through what we actually know about these fish and kill off one or two myths. To finish with I will share my thoughts and ideas about how we are at last going to solve the mystery and get them to breed in the aquarium.

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Clown loach, Chromobotia macracanthus.


Clown loaches come from Indonesia and are found in Borneo (Kalimantan) and Sumatra. They live in rivers for the greater part of the year except for the yearly breeding migration when the breeding adults swim up smaller waterways to mate. They live on the waterbed in large numbers or in shoals. Information about maximum size varies up to 40-50 cm. This must be seen as very rare even in the wild and a more normal adult size would be 15-20 cm, age information is said to be over 20 years.


Clown loach belong to the family Cobitidae, Loaches, the order is Cypriniformes, carp like fish. The main characteristic for this family is a spine under each eye which can be erected as a defense mechanism. Clown loaches scientific name is macracanthus which means "large thorn". Even though the spines are not poisonous, it can be very painful to be stuck by them, believe me! A word of warning, loaches spines easily get tangled up in the fishnet, which in the worse case can cause avoidable damage to the fish. The scales of the clown loach are small and difficult to see, which made some aquarists claim that it was "scaleless", which is incorrect, however it does not have scales on its head. Loaches have four pairs of barbels. Colour and body shape is as seen in the photos.




Native home of the Clown loach! The fishing nets in the photo is for catching edible fish, not especially Clown loaches. Photo; Mikael Håkansson

The vast majority of Clown loaches for sale are caught in the wild, around 20 million Clown loaches are exported every year from Indonesia. Some breeding is done mainly in Thailand with the help of hormones to stimulate matings. Raised Clown loach are still quite expensive compared to those that are caught in the wild. Reports that successful hormone induced breeding has been made for example in the Czech Rep., Russia and in Florida, but it is difficult to substantiate these reports. An increase in farmed Clown loaches is of course wished for. Even though the species is not especially threatened because of the numbers caught in the wild, there are reports from certain areas, mainly in Sumatra, that their numbers are decreasing. Indonesia has forbidden the catching of Clown loaches over 15 cm.s for export, this is to protect to spawn ready fish. Even if wild caught fishes can be a threat to some local occurrences, the question on wild caught or not Clown loaches is not so simple, because for those poor families that have fishing as their sole income, the Clown loach gives an imortant economic contribution.


Information is that the catch on Borneo is made generally between the end of March to the beginning of July when the water recedes after the rain period which is from December to February. Some years young fish can be caught in the rain period of January-February. In Sumatra the high season is earlier, from November to January. In earlier years there was often a shortage of Clown loaches in the shops in Autumn and Winter before the catch started, but now they have started to keep fish in fishcorfs, and in the larger cities equipped with aquarium plants in large cement pools, so that now there is a year round availability. Besides, there is an economical gain, the fish grow under this time and the larger the fish the more it is worth.


Catching the wild fish is interesting. You take hollow bamboo cane up to two metres in length and make a little oppening in each segment of the bamboo. The bamboo is then placed in the water and the Loaches hide in there. When the bamboo is lifted out of the water you can then carefully shake out the fish. This method can be a little different from place to place but is on the principal.


Bamboo cane hanging by string along a river in Sumatra. Besides Clown loaches many catfish, for example Chaca bankanensis (below) are caught under the high season from November to January by this method. Photo: Mikael Håkansson


chaca bankanensis


Mikael Håkansson who recently visited Jambi in Sumatra to study the catching of aquarium fishes there, stated that they hang bamboo cane in the water from a overhanging tree or from a log used as a float. The later method is used mainly under the really high season, bamboo that hangs from the trees is used all year round. The bamboo is cut down in lengths of around two metres and is allowed to dry for two months, there is a substance or smell in fresh bamboo that evidently the fish do not like.


The fish that are caught for aquarium use are from two to seven-eight cm. Of course larger Clown loaches are cathed by other fishing methods such as nets, but these are eaten by the locals. Clown loaches are not a significant source of food even though they are eaten when caught, it is other larger species of fish that are sought after.


Mikael was told that at the begining of the high season for Clown loaches everybody wants to join in, even "old ladies who can hardly walk get a new lease of life and sit in the boats helping to empty the bamboo traps".



A bambootrap is emptied. Photo: Mikael Håkansson


The most well known characteristic of Loaches is that they "click". When they squabble over food or the best place in the hole, they give off a click which is easily heard, sometimes so loud that you think the aquarium has cracked!



Clown loaches are considered a fish that lives in shoals, but I would rather say that they live in groups. The fish quarrel between one and other in a way tha fish who live in a "real" shoal seldom do. This question is of definition is probably more of academic interest. Under no circumstances should these fish be kept alone, they become very unsure, afraid and sometimes aggressive. They are most suitably kept in groups of 4-5 or more. I have read in several articles that old Clown loaches can become aggressive to other species of fish but I have never noticed this, it could simply be that Loaches have been kept alone or in too small a group.

Clown loaches grow quite fast as youngsters, up to 7-8 cm.s, then their is a conspicous slowing down of the growing speed. Young Clown loaches are lively and inquisitive fish who like to be in the front when it is feeding time. My experiance is that older fish are a little more cautious and like to find a hiding place if possible. Clown loaches sometimes lay and sleep in a way which makes them look like that they have died, sometimes they even lay on their sides. When one investigates, the fish swims away as if nothing had happened. Clown loaches otherwise are incredibly fast when they get up speed and are very skilful dodging stones in rapid currents.


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Clown loaches should not be kept singly but in groups of at least 4 or 5.


The most well known characteristic of Loaches is that they "click". When they squabble over food or the best place in the hole, they give off a click which is easily heard, sometimes so loud that you think the aquarium has cracked!


The Aquarium:


A large bottom area is best. Bottom living fish like loaches have no need for high aquariums. Suitable bottom material is aquarium gravel with smaller and larger stones and roots to give a natural environment.


You can try with plants but you have to reckon with a certain loss as Clown loaches like to eat the plants. Swordplants and different Hygrophila-species if you ask a Clown loach are very tasty. Java fern and Anubias manage better, and also vallisneria for example.

The size of the aquarium has to be compatible with the size of the fishes, I do not intend to give any sizes or point any fingers in this case, use common sense. The bigger the better is valid here as it is in most cases concerning aquariums.


Hiding places in the form of holes and caves are good, the fish like to lay in a cave and look out and see what is happening. They happily lay close together, so the holes should be big enough for the whole group at the same time. In my opinion it looks best if the holes are built with larger rounded stones and roots to copy the natural habitat of Clown loaches, but for the fish it does not matter so much what materials you use. I have seen both bricks and grey plastic drainage pipes used which the fish happily used.


Hollow roots can cause problems. I had one such where one of my fish decided to live, to get him out was nearly impossible. I had to wait one week before he decided to come out and I could move them as planned.


The water circulation and filtering is best if set a little higher than in the standard aquarium to be sure of good oxygen flow, no strong stream of water is needed like that in a hillstream aquarium.


Clown loaches make no demands on extreme water elements, normal pH and KH will do excellently. On the other hand one should be careful with extreme water changes, these fish are sensitive to sudden changes in the quality of the water. Frequent small water changes are best. I reccomend changing water at least once every second week, preferably more often.



New names for Botias

Bleeker in 1852 described the Clown loach as Cobitis macracanthus. Later it were moved to the family Botia where they remained until 2004 when the Swiss ichthyologist Maurice Kottelat made them their own family, Chromobotia. In the same work, the family Botia were divided into four smaller families, besides Chromobotia also Yasuhikotakia there the "Mekong loaches" were moved,with modesta, sidthimunki and others. Tiger loaches with among others helodes and hymenophysa were put in the family Syncrossus. Remaining in the family Botia are the "Indian" loaches, for example the Pakistani or "Yoyo" loach, B. Almorhae and B. Striata.


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The Blue loach is now called Yasuhikotakia modesta.




You sometimes see it in the form macracantha instead of macracanthus, according to Sven Kullander of the Swedish Natural history museum there is no doubt that it is macaranthus that is correct.

"Macaranthus in this case is a substantive (large thorn), so it is not changed against the family name, described by Bleeker as Cobitis macracanthus. Because Cobitis is feminine he should have used "macracantha" if he had intended that "macracanthus"should be treated as an adjective (large-thorned)"

Grateful thanks to Sven for this explanation and now we can put an end to this discussion.




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Species name macracanthus means "large thorn" which alludes to Clown loaches errecteble spine under each eye.



It is almost easier to count up what Clown loaches will not eat than what they will eat, they are omnivorous. Rumour has it that they can "clean up" an aquarium from snails, which is nearly true. That I write nearly, is because I have found that they do not eat Malaysian sand snails, which can be recognised by their pointed spiral shaped shell. These snails have a lock which they can close in the shells opening, obviously this is too hard a nut for Clown loaches to crack!


As these are bottom-living omnivorous fish it can be counted on that they eat the animals that live on and in the bottom where they live. Besides snails also crustaceans, worms and larva, for example chironomids, bloodworms, is all likely included in their natural diet. There is usually plenty of small shrimps in tropical freshwater, so probably this is also an important food as is vegetables of different types.


In other words you can feed these fish with everything in the way of food, flakefood, live and frozen animal fodder like mosquito larva, bloodworms, mysis, daphnia, tubifex-worms, etc. Earthworms are delicious but must be cut into suitable sizes first, which some people may think is just too much! Shrimpmix, algae tabletts, fishballs, pellets of different types like salmon, discus or goldfish pellets all work. Brusselsprouts, slices of squash and cucumber parboiled also go down well. Naturally the best way is to feed them food which sinks, but if necessary they can go up in the aquarium and even eat at the top while swimming on their backs. A mixed and varied diet is probably best.


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Bloodworms is one of the Clown loaches favourite dishes. A warning, it is not unusual that we can be allergic to these, so if you feel the slightest discomfort, for example itching eyes or develop a skin rash discontinue using this food.


Healthy Clown loaches eat a lot and often, which explains the need for good filtering. Their voracious appetite makes it easy to be tempted to overfeed which soon leads to water decay. Feed small amounts a few times a day so that the fish do not leave any food scraps over, it can get messy especially if you feed shrimpmix or food pellets as Clown loaches do not have good table manners.


Loaches sometimes go into a "feeding frenzy" which means they hysterically throw themselves at the food with an intensive clicking. Eventhough they are usually foodhappy fish, this is something completely different, it looks like they have never been given food before! My fish behave like this between March-May and can possibly have something to do with seasonal change in their original habitat.


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Clown loaches enjoy food pellets.

Special problems:

There is a couple of things that you should keep watch for concerning Clown loaches. The most common problem is white-spot, these fish are easily struck down by this disease. This often occurs when the fish have been kept too cold or in newly bought fish after being transported. Habitual fish that are well cared for are not more susceptable than others, in the ten years that I have kept these fish privately, I have only had white-spot once. For safety´s sake always have white-spot medicine at home if you acquire botia, it can save lives. White-spot is easily cured but can be a catastrophy if not treated.


N.B! follow the dosage instructions carefully for all medicines, some medicines recommend half the normal dosage for just loaches, because they can be sensitive to some ingredients, mainly coppercombinations.


Loss of weight or "skinny disease" is also quite common in Clown loaches. Typical symptoms are loss of weight and behaviour known as "knifeback" even though the fish is acting and eating normally. This sickness is more difficult to treat, it comes from a parasite organism (spironucleus) in the intestines of the same type that is thought to cause the so called "discus disease". I have successfully removed this disease from newly imported fish by using Spirohexol from JBL in the form of tablets. I have taken one tablet and crushed it and dissolve it in as little water as possible. I have then used discus granules which have been soaked in the solution. It becomes like a thick porridge after a short time when the food has drawn in the liquid. I then feed this to the sick fishes, after a week it looks like the sickness is gone. For the best possible effect do not feed with any other food. Flagyl (Metronidazole) also helps fight against this sickness but at least here in Sweden it is on prescription and can be a little difficult to come by.


Apart from this Clown loaches are not more susceptible than other fish, the above sickness usually occurs in fish that have been stressed during transport or subjected to other stress factors like cold water or poor aquarium hygiene. Do not buy fish that look emaciated! Well looked after fish are seldom sick. To quote my friend Elisabeth Hallberg; "the best way to avoid sickness is to keep the fish healthy".



There are few phenomena in the hobby of aquariums which is the object to so much rumours and speculations as the breeding of Clown loaches. Sometimetimes articles appear or stories that someone has "found" fry in their aquarium, but no photos or other evidence has ever been presented. This does not say that all reports are a fabrication, but we should still sometimes be doubtful. However, there are a few common traits that we cannot disregard. It is often told about "forgotten" aquariums where suddenly fry appear. If this is true, it can mean that the fish do not nead such strong current to spawn. Other experiences speak against this, see below. Unfortunately you have to say, that it would be more simple if we could find a clear-cut recipe of what we should do.


I have kept Clown loaches for around ten years now and especially intensively the last four-five years. I have tried many different ways to encourage my Clown loaches to spawn, but as yet without success. I have made some conclusions which possibly can inspire others to solve the mystery with these lovely fish, so I thought I would give an account of my thoughts and tips here.


First and foremost, if you read articles in books or publications and in different internet forums there is often the statement that Clown loaches have to be very old and very big to be ready to spawn. On the whole it is difficult to understand how such information can be spread around about a species we know so little about. In any case, I have established that this is not true! According to a fishery study of the Danau Sentarum Wildlife Reserve, fish under 8-10cm.s stay at the usual catching areas during the rainy season while the others migrate. Considering that the speed which they grow, we can come to the conclusion that Clown loaches spawn migrate from their second or possibly third year of age.

By accident (caused by my one and a half year old son and some pulled out contacts to filters in my loach aquarium) a pair of my largest examples died. Because I am of the curious type and one of the fishes looked rather round I opened it up. To my surprise it was full of roe! The fish now lie in alcohol at NRM, the Swedish museum of Natural History in Stockholm if anyone wants to control their size, otherwise you can look at the photo below. The roe distended female, top in the photo is around 10-11 cm. SL? Total length around 15cm., far from the 30cm.s some authors state. So giant fish are not needed for Clown loaches to be mature for spawning, so do not let this discourage you from trying.


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Clown loaches with roe! Click for a larger photo. Photo Erik Åhlander, NRM


The most controlled trials that I had carried out and successful to the point that it resulted in the spawn ready female, which is a long way from spawning but still a bit on the way. I began by trying to imitate a little larger river at the end of the dry season and then tried to simulate a "migration" upp in clearer and stronger flowing water.


The aquarium was nearly 200 litres in which I had around ten loaches between 8-12 cms. The bottom layer consisted of gravel, small and larger stones. At one of the short sides of the aquarium was a "filter chamber" built from a 40 x 50cm filter mat which also divided off 20 cm.s of the aquariums length. I had a light water flow (Proportionately, one Fluval 4:, around 1000l/h, it is a little different proprtion with the waterflow when one is keeping such fish.) The water was normal tap water but I added some crushed clay as often in tropical rivers they are rather muddy. The water temperature was quite high, around 30 degrees C.


After a couple of weeks I started to change the cloudy water, lower the temperature to around 27c. and increase the flow of water. After a couple of weeks more when the the water became even clearer, I further increased the flow of water. (Now to four pumps of the same class) and added some alder cones and peat in the filter chamber to get a "more comfortable" water. I also planted some peace lilies in case the fish wanted some vegetation to spawn. Under the whole of this process I fed the fish like an idiot, which meant I had to change half the water at least two times a week, maybe more, except in the beginning when the water quality was supposed to be poorer.


As stated, the fishes never spawned and after about a month more the accident happened, as reported on earlier.

During the work on this article I have had contact with Per-Erik Lingdell who works with insects living in flowing water, he is obviously very serious and has great knowledge how this kind of habitat works and looks like. He told me he actually got fry from Clown loaches but unfotunately could not get them to survive. He used a similar procedure to mine but used stronger flowing water. Above all he had a place where water rushed over little larger stones and there he believed the fish had spawned. He even changed the water condition quicker than what I did. I gave my fish around a month before they were " up in the spawning area". Per-Erik was very knowledgeable and friendly, as loach people mostly are, and I got a lot of suggestions and ideas through my conversation with him.


From the above you can understand that I have not given up, far from it! I have just set up a new and little larger aquarium, around 300 litres. (Sept. 04) where the next attempt at spawning will take place. The measurements are 120x60x40, also quite a large bottom area but not so high. In the filter corner I have made a so called "Hamburg mat filter", where there will be place for some strong filter pumps, Fluval 4 or similar. At the moment only one is in use, I am going to start one at a time to stimulate a stronger water flow. I also have a small outside filter of Eheim ecco brand, mostly to be able to use peat and similar on a controlled basis. All other filter suction is on the inside in the filter corner, as imagine how frustrating it would be if the fish spawned and the roe were sucked up into the filter!


Filter corner. Here you can insert at least four strong pumps if you try a little!

I have an automatic feeder that feeds salmon pellets and discus granules three times daily. I feed delicacies like earthworms or bloodworms when I come home in the evening, often twice with a couple of hours between. I strive after a protein and fat rich diet, I believe this is needed for eventuel roe production. Lighting is of course on a timer so it coincides with my times, it turns on around lunch time and turns off soon after midnight. In the mornings I am too tired and busy with day nursery dropping off and other things to have time to look after the fish.

The aquarium is fitted up with coarse gravel, a little root and some smaller stones, I will fill up with many more stones during "the migration up the river" and maybe at the end also lower the water level to really increase the flow of water.


It is planned that this attempt at spawning shall be on the same model as the first but with some modifications. For example if the fish do not spawn in the strong flowing stream then maybe they will spawn in the quieter water after the small rapids. I have a nice group of eight loaches, the largest is around 13-14cms. The spawning time is in the beginning of the rain season which begins in November-December, so I have a few months to prepare the aquarium and the fish for what is coming, which will, I believe make it easier to hit the target if following the fishes natural rythm for the time of the year. We will have to see how it goes, if it works you are sure to hear about it! Otherwise I will so some other changes and try again, and again and again!


A part of my new Clown loach aquarium, as yet still rather sparsely furnished but on "the way to the spawning ground"more will be added. The water is slightly brown in colour due to humus matter from the peat filter.

Now I have told you how I previously thought and what I plan to do. We aquarists are sometimes a little secretive with what we are doing especially if it is ones own small experiments. Don´t be, your experiences can be very valuable for others, it is known that you learn from "failures". You might think that I am totally on the wrong track and you have other thoughts and ideas of how we are to succeed to get these magnificent fish to spawn. Well then, you might be right! There are not many species of fish that are as beautiful, kind and funny as Clown loaches. They really deserve more who will seriously try to break their big mystery!


Heartfelt thanks to (in alphabetical order):

Elisabeth Hallberg, Bollmora aquariumclub, for ideas and for saving me from logical and linquistic somersaults.

Mikael Håkansson, Imazo, for wonderful photos and accounts from Sumatra.

Sven Kullander, NRM, for thorough explanations in classification and zoological nomenclature. (and lots more)

Per-Erik Lingdell, Limnodata, who so openheartedly told me everything about his Clown loach spawning.

Erik Åhlander, NRM and Bollmora aquarium club, for all our discussions on loaches and everything on fishes.

Eva-Lil Åhlander, my wife, for allowing me to care for my fish 24-7 when needed......

and finaly a special thanks to Paul Stanton for helping me with this English translation.


Referances on the internet:

The fishery of the Danau Sentarum wildlife reserve Richard G. Dudley, 2001. Fishery study. You have to read between the lines sometimes, but very valuable.

Loaches Online  A must for those interested in loaches.

Fishbase All the worlds fish. It is very valuable, but keeping scientific names up to date can take one or two years.

Potential for the Aquarium Fish Trade and Conservation Issues Singapore University, Department of Biological Science, 1998 (probably a student paper, author unknown. Not that scientificly correct in all sections).

Naturhistoriska Riksmuséet, ichthyologi Among other things a new search function with photos, can be fun to browse through.

Besides these, I have read everything I could find on loaches (Cobitidae) and hillstream loaches (Balitoridae) in books, magazines and on the internet in the last five years.

Ola Åhlander

Haninge, Sweden 2004-09-02 ( english version 2004-10-13)