22. Spiny eels (21)

Macrognathus aculeatus “Bangka”

22. September 2023

The small spiny eel Macrognathus aculeatus – the species rarely grows to 20 cm long, even though 38 cm is given as the maximum length in the literature – is one of the longest known species of these bizarre fishes. Already in 1786 it was described by Bloch. As so often with old known species there are exactly therefore a lot of misidentifications in the literature, because the origin was only vaguely known to Bloch; he gives “East India”, which corresponded at that time to the Moluccas, the Indonesian island world and the peninsula Malacca. In this area there are several Macrognathus species similar to each other. Therefore Kottelat and Widjanarti limited the origin to Java in 2005 and established a neotype from there as future reference.

We could now for the first time import beautiful, apparently adult (because the females show clear spawning) Macrognathus from Indonesia, which according to the exporter were collected on the (relatively!) small island of Bangka. Bangka is located east off Sumatra and about 500 km north of Java. These spiny eels are not distinguishable from the neotype and are perhaps the first “real” Macrognathus aculeatus that came alive to Germany – at least recognized.

The care of these animals is easy. They are peaceful, sociable fish that like to cuddle with conspecifics in a lair. However, small fish are seen as a food supplement, you should pay attention to this. Temperature requirements are between 22 and 28°C. Although in nature they seem to colonize peat swamps with strongly acidic black water, the adaptation to “normal” water conditions is good. Any drinking water is suitable for their care. For food it is best to give frozen and live food. They prefer red mosquito larvae, tubifex and the like. After acclimation they usually also accept granulated food. All spiny eels are free spawners, spawning near the water surface in dense plant tangles. Spiny eels do practice broodcare. The sexes differ mainly in the abdominal girth, which is considerably fuller in females.

For our customers: the animals have code 425158 on our stocklist. Please note that we supply exclusively to wholesalers.

Text & photos: Frank Schäfer

Macrognathus maculatus

23. May 2022

Spiny eels enjoy an increasing popularity. More and more aquarists are discovering that it is not always the colorful, constantly visible fish that are fun to watch, but also the more hidden fish personalities that are often only seen when feeding. Among these fish personalities are definitely the spiny eels.

There are spiny eels in different sizes: from the only about 10 cm long Macrognathus pancalus from India to the “giant spiny eel” Mastacembelus armatus with up to 90 cm. Unfortunately, a rule of thumb for size that was very helpful for a long time no longer works. Until scientific revisions of the genus in the last 5 years one could always say well: Asian spiny eels with a clearly separated caudal fin remain small, with those with a circumferential dorsal tail and anal fin one must watch out, they can become half a meter long and as thick as an arm. In the meantime, small species of the latter group are known as well as large ones of the former (the recently described Macrognathus kris from Borneo, which can reach a length of 40 cm).

Macrognathus maculatus has a circumferential fin and originates from Indonesia and Malaysia; reports from other parts of Southeast Asia (Cambodia, Vietnam) probably refer to similar other species. Size-wise, the species is in the middle range. Our animals are fully sexually differentiated (males are much slimmer than females) and 15-20 cm long. In the literature one finds size data up to 28 cm. The variable colored species is in any case very nicely patterned and very peaceful. Only very small fish should not be kept together with them: sooner or later they will end up in the stomach of the spiny eels.

For our customers: the animals have code 425253 on our stock list. Please note that we supply only wholesale.

Text & photos: Frank Schäfer

Synbranchus marmoratus

22. February 2021

Only very rarely marbled swamp eels from South America are available. After a quite long time we now have a number of juveniles from Peru in stock. The species attains a maximum length of about 1.5 m. These very large individuals are always males, because swamp eels change their sex. Most of them are born as females and become males at an age of about 4 years. This type of sex change, which is quite common in marine fish, but very unusual for freshwater fish, is called protogynous hermaphroditism. All species of swamp eel can breath atmospheric air and so survive in very oxygen-poor water.

For our customers: the fish have code 295202 on our stocklist. Please note that we exclusively supply the wholesale trade.

Text & photos: Frank Schäfer

Macrognathus siamensis Red Tail

20. January 2021

At the moment we can once again offer very beautiful – i.e. strongly colored – offsprings of a dwarf spiny eel, which is not yet precisely identified. It is offered under the name Macrognathus aculeatus, but for various reasons it will probably not be this species. It shows the most similarity to Macrognathus siamensis, because like this species our redtail has strong pronounced, broad white bordered eye spots in the dorsal fin. 

In any case they are very pretty, sociable animals, which under normal circumstances are not to be expected to grow much bigger than about 15 cm. All spiny eels are inquisitive and adaptive fish, which can give you a lot of pleasure. However, community fish should not be too small, otherwise they will be eaten. Water temperatures can be between 22 and 30°C, with the middle range being the most favorable. Every frozen and live food that fits into the mouth is eaten, also water fleas catch these fish skillfully from the water column, whereby they take a position like a seahorse. But also granulated food is accepted. Water hardness and pH-value do not play a role for the care, every drinking water is suitable. 

There are two things to keep in mind when caring for spiny eels: absolutely escape-proof aquariums and sufficient hiding places in the form of caves. Since spiny eels also like to dig themselves in, the substrate should consist of sand at least in places.

For our customers: the animals have code 425208 on our stocklist. Please note that we only supply the wholesale trade.

Text & photos: Frank Schäfer

Sinobdella sinensis

2. October 2020

For the first time we have obtained this highly interesting, small spiny eel. The species rarely grows larger than 20 cm and inhabits China and parts of Vietnam. According to its origin, care in unheated aquariums is recommended. In Sinobdella the dorsal, caudal and anal fins are fused together, in Asian spiny eels this is otherwise a sign of large species. From all other spiny eels, the animals differ in the peculiar nose/nozzle region. For us aquarists, the shining white edge of the anal fin is an eye-catching characteristic.

The coloration of S. sinensis (there is only one species in the genus) is individually very variable. Among each other, the animals are peaceful, as one knows this from spiny eels generally. Small fishes are potential prey, other, bigger species are not considered further. One should choose soft sand as ground, in which the spiny eels like to dig themselves. If this possibility is missing, the spiny eels tend to get skin infections. Frozen and live food of suitable size is taken, especially worm food. We assume that settled animals also feed on granules, but there is still a lack of experience.

For our customers: the animals have code 455233 on our stocklist. Please note that we only supply wholesale.

Mastacembelus unicolor

9. February 2018

We import the beautiful fire eel, Mastacembelus erythrotaenia, on a regular basis from Indonesia, usually large specimens, 30-60 cm long. These fish are about as thick as a forearm. Most recently we obtained again four specimens, 50-60 cm long. However, two of them looked totally different. They lack completely the red stripes and spots which are so characteristic for M. erythrotaenia.

We asked Ralf Britz, researcher at the Natural History Museum, London, and one of the leading specialists for that group of fish, for his opinion. He answered that most probably our new imports are Mastacembelus unicolor or – at least – what currently is thought to be M. unicolor. Our sincere thanks once more to London!

The species Mastacembelus unicolor has been described scientifically back in 1831 by Cuvier. This description based on unpublished data and specimens collected by the naturalists Kuhl and van Hasselt, who died at an early age in 1821 and 1823 in Java. They left an important collection of fishes and accurate drawings of fish. Such a drawing also exists of Mastacembelus unicolor. One can clearly recognize the unusual stripe over the pectoral fin and the white seam running along the whole of the dorsal, caudal, and ventral fins. So our new imports – obviously a pair – look at least very, very similar to M. unicolor.

Our pair currently has a light murky skin, but we are sure this will vanish after the fish have settled. Hopefully we are able to import more of these beautiful animals!

For our customers: the fish have code 426726 on our stocklist. Please note that we exclusively supply the wholesale trade.

Text & photios: Frank Schäfer

Mastacembelus pantherinus

17. August 2017

Once more we were able to import an extemely rarely offered species of spiny eel, namely Mastacembelus pantherinus. In the internet this species is in general named M. dayi, but M. dayi has recently proofed to by a synonym of M. alboguttatus. Researcher Ralf Britz – he described, by the way, also M. pantherinus – has solved this confusing puzzle only some weeks ago.

Mastacembelus pantherinus originates from Burma. t has been collected so far only in lake Indawgyi and its affluents. The species attains a maximum length of at least 50 cm and is a large member of the genus. Our specimens currently are 20-25 cm long.

For our customers: the animals have code 426455 on our stocklist. Please note that we exclusively supply the wholesale trade. Available in very limited numbers only!

Text & photos: Frank Schäfer

Macrognathus aculeatus

18. April 2017

Once more we obtained from India (Bengal) wonderful Eyespot Spiny Eels. The fish are of adult size and 12-15 cm long. The only complicated thing in this species is the scientific naming. The Eyespot Spiny Eel attains a maximum length of about 20 cm and ist one of the most colourful species of all spiny eels. One should be very careful during the acclimatisation, as the fish tends to develop a fungus in small wounds, but once the fish is settled it is very hardy and long living.

Formerly it was thought that there is only one species of Macrognathus, namely Macrognathus aculeatus, with an extremely wide distribution over South and Southeast Asia. Nowadays only individuals from Indonesia are thought to belong really to M. aculeatus. The small, striped Eyespot Spiny Eel from Bengal and Bangladesh is still named „Macrognathus aculeatus“ in many books and scientific articles on freshwater fishes of the region, but it´s proper name is – according to the most recent scientific research – Macrognathus aral.

One should keep this beautiful fish in a tank with a well structured equipment – roots, stones, caves, plants – and a soft bottom. Very small fish will be eaten, but against all other fish and conspecifics the Eyespot Spiny Eels are very peaceful. Settled fish will usually accept even granulated dry food, but frozen food items (bloodworm, large Artemia etc.) should be offered, too. Eyespot Spiny Eels spawn often in aquaria; males are smaller and more dainty than the females. Astonishingly these bottom-dwelling fish prefer the roots of swimming plants to spawn in. It is most likely that this hinders the eggs to sink in the deep muddy bottom in the natural habitats of the fish where the eggs would suffer. Spiny eels do not take any further care for their eggs.

For our customers: the fish have code 425155 on our stocklist. Please note that we exclusively supply the wholesale trade.

Text & photos: Frank Schäfer

Mastacembelus sp. „Nargis“

17. March 2017

We could import this new discovery – a spiny eel – for the first time now from Burma. Initially I thought it would be a member of the M.-armatus-group, but the specialist for spiny eels, Ralf Britz from Natural History Museum in London led me to the idea to take a closer look on the caudal fin. Indeed this fin is fairly separated from the dorsal and the anal fin in Mastacembelus sp. „Nargis“ , while it is merged with these fins in the M.-armatus-group. Ralf thinks that M. sp. Nargis is closest to M. caudiocellatus, but of course he also says that more and detailed observations have to be done to proof this. In the meantime it is best to name the fish Mastacembelus sp. „Nargis“.

It is much likely that Mastacembelus sp. „Nargis“ belongs to the medium sized members of the genus and will attain a maximum length of about 25 cm or so. Our (short) experience with the fish shows that it is as peaceful, gregarious and secretly as one expects from a member of this relationship.

For our customers: the fish have code 426215 on our stocklist. Please note that we exclusively supply the wholesale trade. Available in limited numbers only!

Text & photos: Frank Schäfer

Mastacembelus tinwini

9. February 2016

we can offer this beautiful species of spiny eel only very rarely. The
species has been described scientifically quite recently. It is a close
relative of the common spiny eel of Asia, Mastacembelus armatus. Like
that species, M. tinwini reaches a length of about 40 cm. Other fish are
ignored if they are large enough, but small tankmates are taken for

For our customers: the fish have code 426744 on our stocklist. Please note that we exclusively supply the wholesale trade.

Text & photos: Frank Schäfer

Monopterus albinus

27. August 2013

The swamp- or rice-eels are strange-looking fish that become around 75 cm long. In their natural habitat they live deeply burrowed in the mud. These fish can survive even in almost oxygen-free water, because they own a lung that enables them to breath atmospheric air they take from the water surface. Swamp-eels are predators that feed on small fish and shrimps. Swamp eels themselves are regarded as excellent food fish. They are usually marketed alive, for they can survive many hours outside the water.

These fish are no relatives of the eels (Anguilla). As far as it is known the males – which can be recognized by the broader head – build a foam nest. Under this nest the swamp-eels spawn.

Monopterus albinus has been described scientifically already back in 1844, but most subsequent workers regarded the species as a synonym of M. cuchia. One should not confuse M. albinus with M. albus, which is another, valid species! We received very stable M. albinus recently from India. The fish have a very different color compared with M. cuchia, so it seems to be very likely that they represent a good species on their own.

Swamp eels need places to cover in the aquarium, otherwise they feel uncomfortable, become very shy and tend to panic. Settled specimens, on the other hand, become very tame and take the food (dead fish, for example frozen smelt) from a forceps.

For our customers: the fish have code 436254 on our stocklist. Please note that we exclusively supply the wholesale trade.

Lexicon: Monopterus: means “with one fin”. albus: means “white”. albinus: means “whiting”. cuchia: after the vernacular name in Bengal. Pneumabranchus: means “branch of the lung”.

Suggestion of a common name: Golden tulip eel

Text & photos: Frank Schäfer

Angaben zum Tier
Herkunft Indien / India
Verfügbare Größe in cm 30-40

Mastacembelus erythrotaenia 40-45 cm arrived

27. August 2013

We received gorgeous, 40-45 cm long Fire Spiny Eels. These fish are real personalities and additionally they have splendid colours! As an exception we have included the photographer´s hand and fingertip in the pictures to give you an idea how large the fish really are.

For our customers: the animals have code 426509 on our stocklist. Only five specimens in this size available! However, we also have smaller ones in stock. For more informations, please click http://www.aquariumglaser.de/en/fish-archive/spiny-eels-en/Mastacembelus_erythrotaenia_en/

Please note that we exclusively supply the wholesale trade.

Text & Photos: Frank Schäfer

Mastacembelus erythrotaenia

18. September 2012

We do not have only one of the smallest species of spiny eel in stock, eg M. taeniagaster, but also one of the largest: Mastacembelus erythrotaenia. These splendid guys reach us from Indonesia and are real personalities for the owners of large tanks. The largest known specimen was about 1 m long. Currently we have small (8-10 cm), medium sized (20-25 cm) and large (40-45 cm) specimens in stock.

Spiny eels are very calm aquarium inhabitants. They also become very tame. One can train them easily, for example on sounds like a whistle. Once they are trained the large fish come along and pick up food from the tip of a forceps. One can feed the also with bare fingers, but the spiny eels are not always very unerring…

Regarding the water conditions these spiny eels are not very demanding. The water temperature should be between 24-28°C. Such large fish are fed best with frozen food like smelt and shrimps. They also like earthworms very much. Plants and other tankmates are generally not harmed. However, small fish are taken as food.

For our customers: the fish have code 426501 (8-10 cm), 426505 (20-25 cm), and 426509 (40-45 cm) on our stocklist. Please note that we exclusively supply the wholesale trade.

Lexicon: Mastacembelus: is said to be derived from ancient Greek and should means “the one that throws oneself biting”. erythrotaenia: ancient Greek, means “with red bands”.

Text & photos: Frank Schäfer

Angaben zum Tier
Herkunft Indonesien / Indonesia
Verfügbare Größe in cm 8 - 45

Macrognathus taeniagaster

18. September 2012

Basically speaking, the spiny eels of Asia can be divided in two groups: the small species belonging to the genus Macrognathus that reach usually only 10-15 cm total length and the large species of the genus Mastacembelus that grow to a length of more than 40 cm (maximum length reported: 100 cm).

We received a shipment of spiny eels from Thailand that confused us a bit regarding the determination of the species. On the one hand the fish looked very similar to Macrognathus circumcinctus, on the other hand they looked somehow different. The riddle was solved by researching the synonyms of M. circumcinctus. One of these species regarded currently as synonymous with M. circumcinctus is a species described as M. taeniagaster from Thailand. Checking the original description of the latter proofed that we had obtained exactly that fish. Of course this is neither the place nor the medium to decide wether M. taeniagaster and M. circumcinctus represent two different species in the zoological sense. But it is a fact that they look a bit different. The main difference is the presence of a row of ocelli on the base of the dorsal fin in M. taeniagaster which is lacking in M. circumcinctus.

Macrognathus taeniagaster is able to change the colour very fast. The very same fish can be uniformly colored beige in the one moment and in the next can show an almost white back and a dark belly.

Keeping these spiny eels is very easy. The fish like the company of their own kind and often share the same hiding place. Males stay smaller than the females and are much more slim. Macrognathus feed readily on any type of frozen and live fishfood. Very small fish are taken as food, but in general the spiny eels are very peaceful against tankmates and are very suitable for community tanks. The fish spawn near the water surface in the roots of swimming fern etc.. It is possible to breed these fish in aquaria, but this is rarely done.

For our customers: the fish have code 425304 on our stocklist. Please note that we exclusively supply the wholesale trade.

Lexicon: Macrognathus: ancient Greek, means “with big jaw”. taeniagaster: ancient Greek, means “with banded belly”. circumcinctus: Latin, means “girdled thorough”.

Suggestion of a common name: Chameleon tiny spiny eel

Text & photos: Frank Schäfer

Angaben zum Tier
Herkunft Thailand
Verfügbare Größe in cm 6 - 10

Caecomastacembelus brichardi

8. August 2011

One expects blind species of fish from cave systems or the deep sea. But in the rapids of the lower Congo river not less than 5 different species of blind fish exist (among them the only blind species of cichlid of the World, Lamprologus lethops) – and nobody can explain why these fish are blind. One of them is Caecomastacembelus brichardi, which we were able to import once more after many years.

The scientific paper, in which the Blind Spiny Eel is described, is accompanied by a biotope photo. Here one can see large rocks, sometimes protruding from the water, and it is in crevices among these that the Blind Spiny Eel prefers to live.

The species grows to about 15 cm in length (the largest specimen in the type series was 11 cm long); its colour varies from snow-white to a whitish grey, and it prefers a diet of worms and frozen foods. It is important that the food has a strong aroma.

Against conspecifics the fish is completely peaceful. In general, spiny eels are peaceful fish that ignore other species as long as they don´t serve as food.

For our customers: the fish have code 109003 on our stocklist. Please note that we exclusively supply the wholesale trade.

Lexicon: Caecomastacembelus: Latin, means “blind Mastacembelus”; Mastacembelus is another genus of spiny eel. brichardi: dedication name for Pierre Brichard (1921 – 1990).

Common name: Blind Spiny Eel

Text & photos: Frank Schäfer

Angaben zum Tier
Herkunft D.R. Congo
Verfügbare Größe in cm 10-15

Mastacembelus caudiocellatus

9. July 2010

Recently we were able to import this pretty spiny eel from Burma for the first time. It is a rather small (around 20 cm) species with a very contrasting pattern. The species lives endemically in the Lake Inle region in Burma. Lake Inle has medium hard water with a slightly alcalic pH. From Lake Inle already many pretty and very suitable aquarium fish have been imported.

Although the species has been described scientifically in 1893 already it is still new for the hobby. There are two phenotypes in our specimens. Some fish are larger, heavier builded and have a very dark coloration, others are smaller, more elongate and rather brownish. This possibly represents sexual dimorphism. It is – generally speaking – possible to breed spiny eels in the aquarium. They prefer to spawn in the roots of swimming plants near the water surface.

When keeping spiny eels it is necessary to offer a number of hiding places as well as fine sand which enables the fish to burry themselves at least in some parts of the tank. Mastacembelids are exclusively carnivorous, plants are ignored. The worst that can happen is that a spiny eel tries to burry itself under a plant. Spiny eels are generally very peaceful to conspecifics and to other fish. Very small fish, however, are eaten. Due to the quite small mouth of this spiny eel, other fish from 4-5 cm upwards are usually safe. Spiny eels are fed with all the usual live and frozen food, most of them also accept granulated food.

For our customers: the fish have code 426353 on our stocklist. Please note that we exclusively supply the wholesale trade.

Lexicon: Mastacembelus: ancient Greek, means “the one that throws oneself a bite”; probably it was though that these fish can use their snout like the trunk of an elephant. This is, however, wrong. caudiocellatus: Latin, means “with an eyespot in the caudal”.

Text & photos: Frank Schäfer

Macrognathus meklongensis

1. December 2009

We were able to import for the first time one of the smallest and most beautiful species of spiny eel: Macrognathus meklongensis from Thailand.This charming species becomes hardly 15 cm long and only as thick as a forefinger.

The coloration differs very much depending on mood. The basic colour is a nice golden bonze, the fins become yellow-red when the fish feels good, below the dorsal fin (which has black stripes) are small ocelli (eye-spots).

The species is very peaceful against tankmates, may the belong to the own species or other ones. Very small fish will  be eaten, but the spiny eel is not a predator at all. It mainly feeds on small invertebrates, especially moscito larvae and bloodworm, which are also readily taken when frozen. If you have the opportunity to feed live waterflees, you should not miss it! It is really funny to observe how the spiny eels, bringing their body in a S-shape figure (this looks a bit like a seahorse), pick the flees out of the water column.

Regarding water parameters the spiny eels are totally undemanding. Water temperature should be between 22 and 28°C. It is necessary to furnish the aquarium with many caves and other hiding places during the phase of settling in, but after that phase the spiny eels will be visible very often. It is of great importance to cover the tank completely, for spiny eels are real masters of escape.

For our customers: the animals have code 425164 on our stocklist. Please note that we exclusively supply to the wholesale market.

Lexicon: Macrognathus: from ancient Greek, means “with large jaws”. meklongensis: originating from the Meklong river.

Text & photos: Frank Schäfer

Synbranchus marmoratus

6. July 2007

Synbranchus marmoratus

As a beauty in the conventional sense Synbranchus marmoratus can not be chracterised, but even the extraordinary has its attraction. At the moment we can offer beside swamp eels in „normal“ sizes a giant of approximately 1 m length. Of course a predator of this size should not be kept together with small „food fishes “. In addition they try to undertake nocturnal migrations, in order to avoid unpleasant nocturnal meetings, the aquarium should be hermetically closed. For those looking for an alternative to the usual community tank it might be an interesting ornamental fish.(Photo F. Schäfer, Text K. Diehl)

Angaben zum Tier
Herkunft Mexiko - Argentinien, Peru

Macrognathus aral

6. July 2007

Macrognathus aral

This spiny eel originates from South East Asia, i.e. Pakistan, India, Sri Lanka, Bangladesh, Nepal up to Myanmar in their most southern distribution area. This fish is dawn and night active and will eat small fish. Therefore it should only be kept with larger tank fellows. In their natural habitat this species can reach a length of 65 cm, although in the fish tank it might not reach this length. The water of the aquarium should be given some sea salt (1-2 tea spoons per 10 litre of water) and should be well aerated. Any publications about breeding the spiny eels can be found in the literature of the last 40 years only incidentally, although only from the smaller species. Spiny eels make suitable and very interesting subjects for the home aquarium. After a period of shyness the spiny eels will come out at feeding times and can even become a very trusty tank companion. (Photo: Frank Schäfer, Text: Izaak den Daas)

Angaben zum Tier
Herkunft Indien

Mastacembelus greshoffi

6. July 2007

Some time ago we could import Mastacembelus greshoffi from the Congo. Here we have a spiny eel getting approximately 35 cm long, which occurs over rocky bottoms in rivers and lakes, also in rapids. Spiny eels are intelligent fish, they show a multiplicity of interesting behaviours. They also can become amazing tame and eat then literally from the hand of their caregiver. Best meaty food is eaten and rather plenty of it. They like mosquito larvae, worms and also now and then a small fish. Therefore not too small tank mates should be selected for their socialization in a community tank. A complete covering of the aquarium is important, since spiny eels rank among the “escapee kings” under the aquarium fish. With a little luck and smartness the breeding of this species should be possible, some relatives have already successfully be bred in aquaria.(Photo F. Schäfer, Text K. Diehl)

Angaben zum Tier
Herkunft Kongo, Cingo River

Mastacembelus spec. „Kamerun“

6. July 2007

This spiny eel reached us from Cameroon. The classification to a species was so far not possible for us. Since spiny eels predominantly are found on sandy to muddy bottom, they require a sand substrate in which to dig and hide. Flat rocks are also good for these fish to burrow under; just make sure that all rocks and gravel are rounded and not sharp, or the eel may injure its body. The chemistry of water does not play a crucial role, a lighter salt additive is recommended with many species. Spiny eels like to eat small live foods such as, crustaceans, brine shrimp, blood worms, glass worms, tubifex worms and fish. After acclimatisation frozen food as e.g. brine shrimp, blood worms, daphnia, glass worms and plankton will do too. Some Mastacembelus – species have been breeded in captivity. Their pattern of behaviour is very versatile, so that they should been kept more often in our fish tanks.(Photo F. Schäfer, Text K. Diehl)

Angaben zum Tier
Herkunft Kamerun