Dwarf
Gourami Fact Sheet
The scientific name usually used for the Dwarf Gourami is Colisa lalia. For more
details about this, see the section: “Scientific Names” at the end of this
article.
The Dwarf
Gourami is native to India, Bangladesh and Pakistan,
and possibly to Myanmar, Nepal and Borneo. It is found in the tributaries of the Ganges
and Brahmaputra rivers, and is found in slow
moving streams and lakes, and can grow in flooded rice fields.
It has
been introduced to Colombia,
Singapore, Taiwan and Florida
in the United States of
America.
It is probably established in these countries.
It has
also been introduced to The Philippines and Canada, but I do not know if it is
established in these two countries.
Size
As its name suggests this is one of the smaller gouramis. Although 10 centimetres (4 inches) is reported as a maximum size for this fish, most of the ones I see are more like 5 centimetres (2 inches) long.
Water Conditions
The normally recommended temperature range for this
fish is 25 – 28 degrees C (77-83 degrees F).
The Dwarf Gourami comes from the tropics, and is
basically a tropical fish. However, part
of its range includes waterways in the mountainous areas of India, and it has been reported in Nepal which is
not a hot country. The places it has
been introduced to are mainly tropical, but it is surviving in the wild in Florida where it has
apparently escaped from fish farms. The
climate of Florida is not tropical although it
certainly does not get as cold as most of the United States.
Dwarf Gouramis have been bred outside in Germany (In the
summer). A single specimen survived in a
garden pond in the Adelaide Hills town of Mount
Barker right through the winter. These observations
suggest that at least some Dwarf Gouramis have better cold tolerance than is
generally recognised.
A pH of between 6.0 and 7.5; with a hardness of no
more than about 19 dH is suitable for maintaining the adults.
Nitrite
The Dwarf Gourami seems to be particularly susceptible
to nitrites. A good filter should be
used to prevent the build up of nitrites, and the general level of cleanliness
should be high. However, this fish comes
from sluggish waterways and should not have turbulence in all parts of the
tank.
Plants
The Dwarf Gourami comes from water with a lot of
plants, so it should be kept in well planted aquariums.
Food
Dwarf Gouramis are omnivores, and they are easy to
feed with normal fish foods. These
should be supplemented with live or frozen foods like Blood worms or Daphnia.
The Dwarf Gourami is one of the types of fish that is
capable of shooting water droplets at insects above the water and knocking them
into the water.
Breathing
The Dwarf Gourami is a labyrinth fish and can breathe
air as well as water. This allows them
to survive in still water which can be low in Oxygen. My own observations suggest that this fish
cannot get all its Oxygen requirements from the air, and does need some
dissolved Oxygen in the water.
Companions
The Dwarf Gourami is a peaceful fish and can be kept
with most of the tetras and similar fish.
I would avoid the smallest tetras like the Neon Tetra, and also any fin
nipping fish.
I would not recommend it as a companion for any of the
other Gouramis, nor for Siamese fighting fish or Paradise
fish. I would also not put them with any
of the livebearers like Guppies, and also not with Australian native fish like
the Murray Cod. The reason for the
exclusions in this paragraph is to reduce the possibility of transmission of Dwarf
Gourami Iridovirus.
Sexing
The male Dwarf Gouramis of all the colour variations
are brightly coloured, while the females of most colour variations are
relatively drab in appearance. However,
the Coral Blue Dwarf Gourami is an exception to this in that the Female is also
a beautiful Coral Blue colour and is scarcely inferior in colour to the
male. The one thing common to all the
colour variations is that the males all have some red on them while the females
have almost no red.
Breeding
It is extremely unlikely that the dwarf Gouramis will
succeed in breeding and raising babies with other fish in the tank. So you need to set up a tank specifically for
their breeding. Some people have
succeeded with tanks as small as 20 Litres (5 US Gallons), but I prefer a tank
of at least 50 litres (13 US
gallons).
The temperature should be about 27 degrees C (81
degrees F), and the pH neutral or slightly acidic. The hardness should be no higher than 10
dH. Normally the water level is lowered
to about 20 centimetres (8 inches).
Although I certainly recommend doing this, I have also succeeded in
breeding this fish with much deeper water.
The breeding tank should be very well planted with a
variety of types of plant, and including some floating ones.
You should only have one male present, but he can
handle more than one female.
Nest
The Dwarf Gourami is a bubble nest builder. Unlike most of the Gouramis, the male usually
incorporates some floating plants into their nest. As well as actual whole floating plants he
may also incorporate bits of plants that he has broken off and chewed. The nest is relatively large compared with
the size of the fish as well as being more elaborate than that of most
gouramis.
Spawning
The male will entice a female under the nest. They may have a few trial matings. The male wraps his body round the female,
turning her on her side or upside down and he releases his sperm at the same
time as she releases her eggs. Any eggs
that do not float up into the nest the male will pick up with his mouth and put
into the nest. One female can lay up to
800 eggs.
After spawning with one female, the male will entice
another one under the nest and this can continue until he runs out of females
ready to breed. The total spawning
procedure can take several hours. After
spawning the male will add another layer of bubbles to the underside of the
nest. He will defend his nest and the
eggs. The females will need to be
removed without disrupting the nest.
Raising the
Fry
The eggs should hatch in 12-24 hours, and the fry should
be free swimming in about 3 days. It is
safer for the male to be removed once the fry are free swimming.
Dwarf Gourami fry are very small. Some people cannot even see them with the
naked eye, so babies will need microscopic food for some time. Often the first food to be given to them is
green water. This is water with so much
free swimming algae that it looks green.
The babies will grow and be able to eat bigger microscopic food,
generally referred to as infusoria. After
a while they will be able to graduate to bigger food like newly hatched brine
shrimp and screened Daphnia.
Live food is best for the babies, but this can be
supplemented with commercial fry foods.
Filtering
A filter is necessary, but a normal power filter would
suck up many of the babies. People have
different ways of solving this problem.
Some people put a thin cloth over the water inlet of the filter to stop
the fry being sucked in. My preferred
solution is to use a sponge filter.
Conservation
Status
In the wild the Dwarf Gourami provides some food for
the local people. It is quite common
over a large area of its natural habitat.
Indications are that it is not in danger of extinction in the near
future. However, the increasing
development of the areas it is native to as well as the rising sea level that
could threaten the lower lying areas of its range could be a long term threat.
General
Hardiness
Over forty years ago I first kept and bred Dwarf
Gouramis. At that time they could
reasonably be described as a hardy fish.
Unfortunately the ones we get nowadays have lost much of this
hardiness. This loss of hardiness seems
to have been caused be several different things.
They have been selectively bred, producing a number of
different colour variations. It is
likely that many of these are inbred, and suffer from the lack of vigour
frequently caused by inbreeding.
Most of the Dwarf Gouramis bred in places like
Singapore will have been kept in controlled conditions and individuals which
would have died out quickly in the wild will have survived and often been used
for breeding. Related to this is that in
captivity fast growth would have been selected for, and particularly fast
growth under the near forcing diets fed to commercially bred fish. The fast growing fish are often not as hardy
as wild ones.
Disease
Related to the lack of hardiness in many commercially
bred Dwarf gouramis is the fact that many of them are diseased. They are susceptible to the normal aquarium
fish diseases, but one is of particular concern. This is the
Dwarf
Gourami Iridovirus.
This disease kills the Dwarf Gouramis slowly,
sometimes taking as long as a year to kill them. The symptoms include wasting of the fish and
there is little doubt that before this disease was identified, fish
tuberculosis was blamed for some of the deaths from this virus. This virus may have become a problem because
of the extensive inbreeding of this fish in Singapore.
Many virus diseases are specific to a single species, and
it is frequently reported that only Dwarf Gouramis can get the Dwarf Gourami
Iridovirus. However there are also many
conflicting reports.
One study by a team led by Professor Richard
Whittington of the University of Sydney, Australia found a 99.95% genetic
similarity between the Dwarf Gourami Iridovirus and a virus outbreak in 2003
that killed farmed Murray Cod, Maccullochella
peelii peelii. A test showed that
Murray Cod can be infected with the Dwarf Gourami Iridovirus, and had 90%
mortality.
There is fear that the Mosquito fish (Gambusia
species) can act as a carrier for this virus and aid its spread through wild
fish populations. This virus has also been reported as affecting swordtails.
One of the problems with these reports is that there
are many types of fish Iridoviruses.
Some of them will kill or make the fish ill while others seem to have no
bad effects on the fish. To really find
out what is happening would take a major research effort.
Several internet articles say that 22% of Dwarf
Gouramis coming out of Singapore
have this virus. This figure is actually
based on an study of Dwarf Gouramis in Australian retail aquarium shops. The study found that 22% of these fish were
infected with this virus. All the tested
fish had been imported from Singapore. The fairly reasonable jump was made to state
that 22% of the Dwarf Gouramis coming out of Singapore were infected.
Of course all the tested fish would have been through
quarantine and any fish showing signs of disease would have been
destroyed. If any batch of fish had a
lot of diseased specimens the whole batch would have been destroyed. If an importer loses a whole batch of fish he
has lost a lot of money and would look for another supplier.
At least one normally reputable internet site says
that most of the fish coming out of Singapore
are infected. 22% is a very worrying
figure, but it certainly is not “most”.
Government
Action Needed Now!
The trade in ornamental fish is a major part of Singapore’s
trade. If there is a problem this
serious with Singapore’s
fish, it needs to be fixed.
Some years ago, a large ornamental fish farm in Australia had a
serious problem with a fish disease.
With government help they systematically eradicated the disease. This fish farm now has an extremely good
reputation for the quality of their fish.
Unfortunately they do not breed Dwarf Gouramis.
The
government of Singapore
needs to recognise that there is a serious problem and to solve it before Singapore’s
export trade in fish is ruined.
Common Names
In English, the Dwarf Gourami is called by many
different names, including ones that cause considerable confusion between the
species and similar ones. Some of the
other English names used for the “Dwarf Gourami” are: “Dwarf Gouramy”, “Red
Lalia” and “Sunset Gourami”.
In French it is called “Le Gourami nain”
Scientific Names
According to Fishbase, the
accepted name is “Colisa lalia”, (Hamilton,
1822) but in
2009 there was a proposed revision of names, changing the name of the genus Colisa to Trichogaster. This would make the correct name “Trichogaster
lalia”. Other names that have been used include: “Trichogaster
lalius” (Hamilton, 1822), “Trichopodus
lalius” (Hamilton, 1822), “Trichopodus lalius”, (Hamilton, 1822), “Polyacanthus lalius” (Hamilton, 1822), and “Colisa
unicolor” (Cuvier,
1831).
Sources
Fishbase: "http://www.fishbase.org/Summary/SpeciesSummary.php?ID=4774&AT=Dwarf+Gourami">http://www.fishbase.org/Summary/SpeciesSummary.php?ID=4774&AT=Dwarf+Gourami
Revision of Genus Names.
Dwarf gourami iridovirus:
"http://www.practicalfishkeeping.co.uk/content.php?sid=1108">http://www.practicalfishkeeping.co.uk/content.php?sid=1108
