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The Nemacheilidae are a family of loach-like fish often lumped with the loaches in aquarium books but differing from them in a number of important respects. They are, for example, very specifically adapted to cool, oxygen-rich fast-flowing habitats such as streams, so many aquarists refer to them as the Hillstream Loaches. Most are quite small fish, typically 8-10 cm in length, making them eminently suitable to maintenance in home aquaria. But they do need good water quality, strong water currents and lots of oxygen, so they aren't fish for the average community tank.
Getting hold of Hillstream Loaches isn't difficult, with several species now regularly appearing in aquarium shops. Places like Maidenhead Aquatics at Crowland that specialise in loaches and catfish often have several Hillstream Loaches in stock, but species like the Sumo Loach (Schistura cf. balteata) is becoming a hobby staple and not at all hard to find.
In this article we'll review some of the species you're likely to encounter, but we'll start by looking at the needs of the group as a whole.
Distribution and habitat
Hillstream Loaches mostly come from Asia with a few species also being found in Southern Europe and the northernmost part of North Africa. Almost invariably they inhabit warm-temperate to subtropical environments where the water is not too warm and well oxygenated. Water currents are generally strong. As a group they are all very well adapted to living on the substrate, and exhibit features such as a torpedo-like body and reduced swim bladder that make it easier for them to stay close to rocks and pebbles without being washed away by the flow of water.
Aquarists keeping Hillstream Loaches need to create an environment that reflects their particular origins. These fish generally aren't too fussy about water chemistry, though soft to moderately hard water (2-12 degrees dH) is perhaps the ideal. But what really matters to them is water quality. Strong filtration is essential, and ammonia and nitrite levels must be kept at zero at all times; these are very much fish for well-established aquaria.
Water temperature is another important parameter. While few species need genuinely cold conditions, most will do poorly if kept at standard tropical temperatures. In general, the aim is to maintain Hillstream Loaches at between 20-24 degrees C.
Social behaviour and compatibility
Hillstream Loaches are mostly territorial and tend to work best kept either singly or else in large groups. If kept in groups of five or more specimens it should be possible for any bullying to be diffused among all members of the group, but if only a small number are kept it's common for the dominant specimen to end up harassing all the other members of its species. Naturally, the size of the tank will need to be considered as well, but err on the side of caution, and be sure to provide plenty of hiding places throughout the tank so that each specimen can set up its own safe domain.
Because Hillstream Loaches require relatively cool conditions (though not true coldwater conditions) their compatibility with other fish will be somewhat limited. Obvious companions will include fish from the same sort of environments, such as minnows and Barilius spp Hillstream Trout. These occupy the upper level of the tank and will generally ignore the Hillstream Loaches, and in turn, will be ignored by them. On the other hand, bottom-dwellers like the Balitoridae (such as Sewellia spp.) might seem viable having similar origins but are much more shy and retiring. Hillstream Loaches can be a bit thuggish at times, and in a crowded tank forcing them to coexist with balitorids can be fraught with dangers, not least of which is competition for food.
Care and feeding
Feeding Hillstream Loaches is not difficult; indeed, as mentioned above, they may end up stealing food from slower bottom-dwelling fish species. Small wormy foods are the most popular foods, things like bloodworms and glassworms, but as ever, live tubifex should be avoided because of the risk they pose in terms of parasites.
As well as these foods, sinking pellets and other standard catfish and loach foods will be accepted as well.
Two Acanthocobitis are regularly seen in British aquarium shops, the Zipper Loach Acanthocobitis botia and the Cherry-Fin Loach Acanthocobitis rubidipinnis.
The Zipper Loach is a greenish-silver fish with mottled upper surface and a distinctive straight line running from behind the gills onto the caudal peduncle. It is native to a broad area across South and Southeast Asia from Pakistan to China. Maximum length is around 10 cm, and no obvious differences between males and females are known.
The Zipper Loach is an excellent aquarium fish. It is adaptable and not too fussy about either temperature or oxygenation, and can do well in clean, well-maintained community tanks that aren't overstocked. So provided the water temperature is between 22-26 degrees C, this would be an excellent species to keep alongside such species as Danios, Swordtails and Corydoras catfish that also enjoy somewhat cool conditions. Zipper Loaches are best kept in groups; they can be a bit shy if kept alone.
Cherry-Fin Loaches are much like Zipper Loaches in size and shape, but their colouration is very different. Basic body colour is pale brown fading to off-white on the belly, with mottled brown markings on the upper surface and orangey-red fins and barbels. Males and females are very similar, but males tend to have more intense colouration, particularly the fins. They are bold rather than aggressive, and do well with non-aggressive medium-sized community fish.
Like Zipper Loaches, Cherry-Fin Loaches are not especially demanding and can be kept at comparatively warm conditions between 22-26 degrees C. Males can be territorial though, and will squabble amongst themselves.
Several different Nemacheilus species are seen in the trade, all of which are pretty similar in terms of size, appearance and requirements. Nemacheilus fasciatus is a typical species that gets to about 7 cm in length. It is native to Sumatra and Java. Nemacheilus fasciatus is not fussy about water chemistry providing extremes are avoided, but does need to be kept moderately cool, around 22-25 degrees C. Like all Nemacheilus, Nemacheilus fasciatus is gregarious but territorial, so it's best kept as a decent-sized group in an aquarium with plenty of rocks and other hiding places.
The various Schistura species are probably the most popular members of the Nemacheilidae, not least of all because of their attractive colours and lively behaviour. They are aggressive towards each other though, and while they are often kept in groups it is important not to overcrowd them and to ensure that there are plenty of suitable hiding places. If keeping groups, be sure to keep at least 5, and ideally more than that. Keep a close eye on them for signs of persistent fighting such as raggedy fins or specimens looking underweight because they're being bullied.
The Sumo Loach is the classic example. It is native to Burma and inhabits fast-water streams much like those favoured by other Nemacheilidae. It is often referred to as Schistura balteata but may or may not be precisely the same fish as the one described by scientists as Schistura balteata, so the name Schistura cf. balteata is often used instead. In any case, the Sumo Loach is quite variable. It is basically greyish with two red or orange vertical bands below the dorsal fin while the back half of the body, including the tail fin, is yellow to orangey-red. Adult length is 6-8 cm.
The "real" Schistura balteata is only occasionally traded under the Sumo I Loach to contrast it with the species described previously, which is sometimes called the Sumo II Loach. Schistura balteata is slightly bigger than Schistura cf. balteata and less intensely coloured, but otherwise similar, though some aquarists maintain that it is a bit more aggressive than Schistura cf. balteata.
Schistura corica is another widely traded species. It is a South Asian species exported from India and Pakistan. Schistura corica is silvery-brown in colour with brown patches and saddles on its flanks and back. It is notable for being one of the smallest Schistura, fully-grown adults being only 4-5 cm in length. It is a relatively intolerant species most easily kept alone, though it is possible to keep large groups successfully in spacious aquaria.
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