Loaches
Those Underrated Bottom Dwellers
by Elaine and Randy Rude, Calgary Aquarium Society
originally published in The Calquarium Volume 39, Number 6, February 1997
Aquarticles
Loaches are popular tank inhabitants in our community aquaria. Many of these bottom
dwellers are nocturnal so we may not see them all that frequently and may possibly forget
they are even there. In this manner they are generally not well appreciated fish, however
they are an important part of any tank. There are seven genera of loaches generally kept
in our aquaria: Acanthopsis (long-nosed loach), Pangio (kuhli loach), Botia
(clown loach), Cobitis (spotted weather loach), Lepidocephalus
(Manchurian loach), Misgurnus (weather loach), and Noemacheilus
(European loach). Loaches are generally found in cool and tropical waters of Eurasia
though some of the Noemacheilus genus whose native waters drain into Northern
Africa, are also found there, one representative as far south as Ethiopia.
Loach anatomy generally reflects their bottom dwelling lifestyles. Their mouths face
downwards and are equipped with prominent fleshy barbels that are well equipped with taste
receptors. Depending on the species, there may be three to five pairs of these fleshy
barbels present. The barbels are used extensively when grubbing through the gravel at the
bottom of the tank for goodies.
The eyes of the loaches tend to be small and are frequently covered by a transparent
fold of skin, presumably for protection. Most of the loaches lack scales, but when they
are present they tend to be small and deeply embedded in the skin, making it difficult to
identify them. Body colors vary widely from the bright black and orange bands of the clown
loach, the red fins and bluish-gray body of the red-finned loach, to the brownish tones of
the weather loach. As well, body shape differs amongst the different genera ranging from
the Botia species which have laterally flattened, high-backed, compressed bodies,
to the Pangio loaches which have elongated, worm-like bodies. Most species of
loaches live in the fast running waters of streams and rivers so they have developed
strong vertical fins, especially the pectoral fins. Due to their bottom-dwelling habit,
they tend to have under-developed swim bladders which makes it easier for them to remain
on the bottom in these fast waters. Interestingly, some species of loaches are able to
gulp atmospheric air which they keep in their intestine to use as a secondary respiratory
organ. Misgurnus fossilis is one loach capable of doing this and so can live in
poorly oxygenated waters. All loaches possess very sharp, bony spines behind their eyes
that they can unfold and use to warn off other fish (and the occasional fish keeper who
insists on taking them to shows).
Loaches are easy fish to keep in the aquarium. Some (such as the weather loach) come
from colder waters throughout Europe and so do better in tanks that are kept below 24C,
whereas those loaches (such as the Pangio and Botia species) come from
tropical Asia, and do better in temperatures above 24C. We know of one club member who
keeps his weather loach in his pond during the summer where it is most effective in
cleaning up algae and insect larvae. Consequently, when acquiring loaches it is best to
research their temperature requirements first. Other than temperature, loaches are very
tolerant of most tank conditions. Most appreciate slightly alkaline, clean water with lots
of plants and places to hide. Hardness and pH do not seem to be important factors with
these fish. The worm-like loaches appreciate a fine-graveled bottom as they tend to burrow
into it. This often makes them a difficult fish to show as they dive for cover the minute
the judges come by!
Feeding is not much of a problem as loaches will eat anything and everything. Flake,
shrimp and Spirulina pellets, live foods, frozen foods, and tubifex worms
(freeze-dried) are all accepted eagerly. However, like catfish, loaches should not be left
to pick up only scraps from the bottom. Sinking food should be included in daily feedings.
The Botia species have a special fondness for snails and will rid your tank of
any snails very quickly. As well, raw or boiled zucchini (boiling the zucchini causes it
to sink) is also received and devoured with great relish. You can almost see the rapture
on their faces when these delicacies are placed in the tank. Most of the time it is a
fight between the plecos and the loaches to see who gets the most zucchini. Weather
loaches will literally turn inside out if offered tubifex worms, live or
freeze-dried. We never see our weather loach eat but when the tubifex worms come
out he will eat right out of your fingers. It does not take him long to sense the presence
of tubifex in the water.
Spawning of loaches has met with varying degrees of success. Misgurnus fossilis,
Cobitis taenia taenia, Pangio kuhli, and Botia macracantha have been
successfully spawned in captivity though with great difficulty. All others have yet to be
spawned successfully.
We keep four types of loaches: Botia sidthimunki, Botia macracantha, Botia morleti,
and Misgurnus fossilis. Our favorite loach of all is the clown loach. One of the
first fishes we purchased when we started our first aquarium was a trio of clown loaches.
These loaches can be quite expensive (more so then other Botia species) possibly
due to a depletion of wild stock and because they are fairly slow growing. Clowns tend to
be very susceptible to ick as over the years we have had to treat our clowns several times
for this ailment. Consequently, this is one of the loaches that requires warmer
temperatures. They are very attractive with broad bright orange and black vertical bands,
and are one of the most colourful of freshwater fishes. We have several age-groups of
clowns as I can not resist the babies that come in every year in the late fall. Clown
loaches are best kept in groups of three or more as they will do poorly if kept alone. Our
largest is approximately 15cm long and is a male, while the smallest is barely over 2 cm.
We purchased Bozo (the big guy) when he was only 3 cm or so, so in five years he has grown
fairly quickly for a loach. Adult clown loaches can achieve a size of 30 cm in the wild
but rarely more than 18 cm in the aquarium. The large clowns are considered tasty eating
in their native lands. The best way to sex these fish is to observe their tail shapes.
Females have straight tips while the males' tips curve inwards. They prefer warmer
temperatures and tanks that are very well planted with lots of hiding places. To encourage
these loaches to be more active during the day, subdued lighting is generally effective.
These loaches can be quite entertaining, displaying lots of personality. Our three
largest occupy a 200-litre community tank and are always bulldozing their way through the
other inhabitants while grubbing around. Clowns have an unnerving habit of lying on their
sides almost as if to sleep. The first time we saw this we thought the fish had died, or
was well on its way, it lay so still. However, approaching the tank always made the fish
zip off as if you had just interrupted a well deserved afternoon siesta. Wouldn’t it
be a fascinating sight to see whole schools of these fish in their native waters all lying
on their sides taking a quick zzz? Another interesting habit of clowns (and other Botia)
is the clicking noises they make. These sounds are used when skirmishes occur amongst tank
mates or when they are warning other tank mates away. These clicking sounds are quite loud
and can be heard all over the house.
Clown loaches have been successfully bred in the home aquaria but usually only by
accident. Reports of greater success in spawning clown loaches with injections of
pituitary gonadotropic hormones has come out of the Orient. All successful spawnings seem
to have occurred with large, adult fish. In the wild these loaches spawn during the rainy
season in foamy, fast running, spring-fed waters in Indonesia, Sumatra, and Borneo. The
fry grow up in slower or standing waters in the lower estuaries of these streams.
Our small school of Botia sidthimunki are always a delight to watch. This
dwarf loach only reaches an adult length of 5.5 cm and is the smallest of all the loaches.
It is a peaceful, schooling, lively little fish that is very active during the day. These
fish have interesting markings with dark lateral and dorsal bands interspersed with
circular spots separated by dark to light gray vertical bands on the upper half of the
body. The lower half of the body is cream to white. Dark spots may or may not be present
on the caudal fin. Our school of four makes quite a sight dashing about the bottom of a
120-litre community tank. We’ve nicknamed them "the weasels" as they remind
us of the weasels in the movie "Who Framed Roger Rabbit?", always erratically
zinging about as if a few bricks short of a full load.
These little loaches hail from small, muddy lakes in northern India and Thailand and
thus prefer warmer temperatures, 26C to 28C though ours do well at 24C. The tank bottom
should be covered with fine gravel and a layer of mulm to keep the dwarves happy. Lots of
plants, rocks, and caves for hiding places are also preferred. All community tanks should
include a school of dwarf loaches!
Botia morleti, commonly called Hora’s loach or the skunk loach, is a
slightly more aggressive loach than other Botia species. We keep three in a tank with two
pairs of South American cichlids (Herichthys ellioti and Geophagus
steindachneri) and armored catfish where they get along fine. We have heard reports
of these loaches being too aggressive and destructive for other smaller tank mates. This
has not been our experience as our three were kept with Apistogramma, tetras, and
barbs with no problems. The literature states that B. morleti are nocturnal but
ours seem to be busy all day. They obviously have not read the books! They are poorer than
average swimmers and seem to launch themselves off the bottom for short distances before
falling back to Terra Firma.
Skunks are quite attractive. They have fawn-colored, smooth, scaleless bodies with a
black stripe that runs along their back from the tip of their nose to the base of the tail
where it curves down laterally. Small black spots may be present in the caudal fin. They
inhabit the waters of northern India and Thailand and actually prefer slightly acid, soft
water, though ours seem to have done well in our hard, alkaline water. Baensch states it
is impossible to sex these fish. However, of our three one is incredibly plump and broad
whereas the other two are noticeably skinnier. We surmise that the fat one is probably a
female. We find these loaches quite entertaining as they seem to do more clicking than our
other loaches and are very active. This is a species we would recommend for more active
tanks.
Our weather loach (Misgurnus fossilis) came to us from a club auction where we
picked him up for the princely sum of $1. The most interesting thing about these long,
brownish, eel-like loaches is their response to pressure changes brought about by weather
systems. With pressure changes these fish become very agitated and swim energetically
around their tanks. In Cochrane, pressure changes are daily occurrences so in our tank our
weather loach is quite active. Despite their size, up to 30 cm, these loaches are peaceful
sedentary fish that are more active at night. The barbels of this fish look like a frill
around the mouth, giving it a rather comical appearance. They like to dig in the gravel so
fine gravel is preferred. However, ours rarely disturbs any plants. Like other loaches,
weather loaches prefer well-planted tanks with lots of rocks and caves for hiding spots.
This is one species that has been successfully spawned in captivity. In between sinuous
movements the eggs are usually deposited on plant leaves. The spawning season runs from
April to July, coinciding with spring rains in the cooler waters of European rivers. While
not the most attractive of the loaches, the weather loach seems to have been left over
from a more prehistoric time making it an interesting specimen for any community tank.
While this has been a general overview of those fish commonly known as loaches, we hope
it will encourage aquarists to try and keep more loaches. Many are attractively colored or
patterned and all are certainly entertaining and interesting aquarium inhabitants. Have
you had your loach today?
REFERENCES
Baensch, H & Riehl, R. (1991). Aquarium Atlas. Melle, W. Germany.
Loiselle, P. & Pool, D. (1993). Hobbyist Guide to Catfish and Loaches.
Tetra Press, Blacksburg, Virginia.
Other aquarium clubs and non-profit organizations can use this, or other articles,
in their own journals or web sites, provided that credit is given to the author, the
Calgary Aquarium Society, and The Calquarium. In the case of a reprint in a hardcopy
publication, two copies of the published work are sent to the Calgary Aquarium Society at
its mailing address. And in the case of a reprint in an Internet publication, a link back
to the original article site must be provided in a prominent location. |