Red
Rainbowfish Fact Sheet
The Red Rainbowfish, Glossolepis incisus, is endemic to Lake Sentani
and the streams flowing into it. This means that it is native to these
waterways and does not naturally occur anywhere else.
Lake Sentani
Lake Sentani is
in the western section of the Island
of New Guinea. New Guinea
is politically divided into two sections.
The eastern section is the main part of the independent country of Papua New Guinea, while the western part is the
West Papua province of the Republic
of Indonesia. Before 2007 it was called West Irian Jaya.
It is a
beautiful lake that is becoming popular as a tourist destination. The Red Rainbowfish lives in areas of the
lake and surrounding streams that have dense aquatic vegetation.
Water Conditions
Lake Sentani is very close to the equator, and the lake itself is
only about 73 metres (240 feet) above sea level. The area it is in is hilly, so the streams
flowing into it will be somewhat higher, but basically the Red Rainbowfish is
equatorial and should not be subjected to cold conditions. A suitable temperature range in an aquarium
is between 21 and 28 degrees C (between 70 and 84 degrees F). The Ph can be between 6.5 and 8.5 although I
would tend to avoid the extremes and aim for slightly alkaline. A water hardness of between 8 and 25 dH is
acceptable.
This is not a small fish and should not be kept in a
small aquarium. I suggest that they need
a minimum of a metre (3 feet) long tank.
The water needs to be kept in good condition and
frequent partial water changes are needed as well as a good filter.
Plants
This fish comes from areas with a lot of plants. You should imitate this in an aquarium with
these fish.
Food
The Red Rainbowfish is an omnivore and will eat normal
fish foods readily. They certainly
benefit from live or frozen foods, but they will also eat plants includingDuckweed although they are not quite a keen on this plant as the River Murray
Rainbowfish.
Length and
Longevity
The maximum size claimed for the Red Rainbowfish is 15
centimetres (6 inches) long, but most of them never reach anywhere near
this. This fish can live for 8 years.
Companions
The Red Rainbowfish is a peaceful schooling fish. The ideal school size for this fish is at
least 10 fish of roughly equal numbers of each sex. This is another reason why it is more
suitable for a larger tank.
Although I would avoid putting it with very small fish
like Neon Tetras, it is a suitable companion for most peaceful community fish.
Sexing,
Temperature and Colour
Only the males get the bright red colour that gives
this fish many of its common names. The
females are Olive brown in colour, with clear fins. Young fish of both sexes also have the female
type colouring. Generally fish need to
be nearly 5 centimetres (2 inches) long to display their adult colouration.
As the males get older their back gets more arched.
The males not displaying their extreme red colours are
a dusky brown.
There are two situations where the males will display
their bright red. At higher temperatures,
the dominant male will have the bright red while the other males will not. At temperatures near the lowest parts of
their range, all the males can become bright red.
Breeding
There are different ways of breeding this fish. The one suggested here is the one I prefer
because it is a bit closer to natural breeding rather than forcing the fish to
produce the maximum yield of eggs.
Select the best looking pair of fish, and put them
into a very well planted tank of at least 120 litres (30 US gallons), but the
bigger the breeding tank the better. The
plants should include some fine leaved ones like Java Moss. There should not be any other fish in the
tank.
Feed the adults well, including rich live or frozen
foods like Daphnia, Mosquito larvae or Blood Worms. The frequency of feeding is important, and 3
or 4 meals a day is not too much. If
enough live food is available this is easier.
The temperature of the breeding tank can be about 26
degrees C (79 degrees F). When they are
ready the parents-to-be should lay eggs on the plants. These eggs take 6-7 days to hatch. The parents usually do not eat their eggs or
babies and the family can be kept together.
The parents will continue laying a few eggs a day for extended periods. The babies will be feeding on infusoria when
they first become free swimming. In a
large, well planted tank there will be quite a lot of this, but you can
supplement the naturally occurring infusoria with cultured infusoria and with
commercial fry foods. Live Daphnia will
provide food both for the parents and the growing babies.
The water quality of the breeding tank is important,
so avoid putting in too much of foods that may pollute the water, and very
carefully do frequent partial water changes.
For the breeding and growing tank I prefer air
operated sponge filters.
Vulnerable
The IUCN Red List classes this fish as
vulnerable. It lives in only one
connected set of waterways in an area which is heavily populated and with a
rapidly growing human population. This
in itself is a threat because of the rubbish and other waste that can get
dumped in the lake and streams. This
increases both as the human population increases in number, and usually also as it increases in affluence. That is, unless proper steps are taken to control
our pollution, richer people cause more damage to ecosystems than poor
people. This does not have to be so.
However, a bigger threat is the plan to use Lake Sentani
as a fish farming area. There is nothing
intrinsically wrong with fish farming, but the way it is normally done is to
bring in exotic species like Tilapia which can potentially wipe out species not
adapted to this predator.
The Lake Eacham Rainbow Fish was wiped out in Lake Eacham
by the introduction of predatory fish to improve the fishing for recreational
anglers. This was done by fishermen with
the apparent approval of the local government of the area.
There is a very real danger that the Red Rainbow fish
will join the increasing list of fish species that have been wiped out in the wild
by the degradation of their habitats and the introduction of fish not native to
the area, and whose extinction is being unfairly blamed on the collection of
these fish for aquariums.
Common Names
Although only the males can get the really brilliant red
colour, and even then only under specific conditions, many of the names in
several languages include a reference to the colour. Some of these names are: “Red Rainbow Fish”,
“Salmon Red Rainbowfish”, “Salmon-red Rainbow Fish”, ‘Red
Irian Rainbowfish’, “Arc-en-ciel Rouge Saumon”,
“Roter Guinea Regenbogenfisch”, “Lachsroter Regenbogenfisch”, “Kammschuppen-Regenbogenfisch”
and “Purppurasateenkaarikala”.
There are other names referring to meat so they
probably have the same idea of redness behind them. Some of these names are: “радушница
гребенчешуйная”, “舌鱗銀漢魚”,
and “舌鳞银汉鱼”.
There are only a few common names not referring in
some way to the red colouration. 2 of these names are: “Lake
Sentani Rainbowfish” and “Irian Jaya Rainbowfish”.
Scientific
Name
In contrast to the large number of common names for
this fish there is only one scientific name.
This is “Glossolepis incisus” (Weber, 1907).
Sources
