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MEMBER
ARTICLE - WEST AFRICA
Keeping
and breeding Nanochromis parilus Roberts & Stewart,
1976
by Andrew Wood
Background
The genus Nanochromis
(Pellegrin, 1904) currently contains 11 described species
which include, amongst others, Nanochromis consortus,
N. nudiceps, N. parilus, N. splendens,
N. teugelsi, N. transvestitus and N.
wickleri. An additional number of species still await
formal description.
Recently the genus
Congochromis (Stiassny & Schliewen, 2007) was
erected to include three species previously assigned to Nanochromis
(N. squamiceps, N. dimidiatus, and N.
sabinae). This separation is based on a suite of anatomical
features that can be regarded as unique to this new genus.
These dwarf cichlids
are all found within the Congo system, which includes the
Democratic Republic of Congo, Congo and the Central African
Republic. They are very slender cichlids that exhibit strong
sexual dimorphism and dichromatism. As in many cichlid species,
the males reach a larger size than the females and tend to
show longer extensions to the dorsal, anal and ventral fins.
When females enter breeding condition they develop a very
pronounced, large rounded belly area (due to the eggs contained
within) and the size of which I have yet to see replicated
in any other group of cichlids.
All members of the
genus are regarded as cave spawners. The eggs and larvae are
generally guarded by the female while the male takes on the
role of protecting the territory. Once the fry are free-swimming
both parents actively defend the territory from intruders.
For successful breeding most species will require soft and
acid water along with a good supply of food to bring the adults
into full breeding condition.
It should be noted
that intraspecific aggression can be a major problem with
this group of cichlids. Aquaria for breeding and maintenance
should be designed with this in mind and plenty of caves and
cover provided to allow the fish to escape from each other
in times of high aggression.
Specific traits
The
slender body shape is typical for this group of fish. Older
males may sometimes develop a small hump on the head and develop
a filamentous extension on the upper part of the caudal fin.
Nanochromis parilus has often been confused with
N. nudiceps; these two different, but closely related
species share an overlapping distribution area. The problem
can be traced back to the 1960’s when N. parilus was
first introduced to the hobby under the name N. nudiceps.
At that time N. nudiceps was the only goby-like species
of Nanochromis known and although N. parilus was
formally described as a new species by Roberts & Stewart
in 1976 the trade were slow to catch on to this fact and it
is still often misidentified to this day. Fortunately they
are easily distinguished by their different caudal patterns,
in N. parilus the upper half of the caudal fin always
exhibits an alternating pattern of black and white (to yellow)
stripes, a feature not seen in N. nudiceps.
Female
displaying to male, fry are in the cave behind the pair. Photo
by A Wood.
Sexual
dimorphism
In
both sexes the upper half of the body has a dull grey coloration
while the bottom half appears more turquoise. Males possess
longer extensions to their dorsal, anal and ventral fins when
compared with the female. Their maximum size is quoted at
4.4 cm (SL). The dorsal fin has a black margin, followed by
a white inner margin; this inner margin always appears deeper
in females than it does in males. Again, while both sexes
exhibit an alternating pattern of black and white (to yellow)
stripes in the upper half of the caudal fin, in females the
lower half of the caudal fin is devoid of markings while in
the male the lower half of the caudal fin may appear pale
(to almost transparent) violet or may exhibit rows of red
spots, or a combination of both. Females that are in breeding
condition will develop an extremely swollen, violet coloured
belly and their genital papilla will be easily visible.
Male
on territorial duties. Photo by A Wood.
Distribution
Congo
(Brazzaville) and the Democratic Republic of Congo, around
Kinshasa.
Ecology
Large
numbers of N. parilus are reported to be found in areas of
slow moving water along the banks of the Congo River near
Brazzaville. Although viewed as a moderately rheophilic species
by Roberts & Stewart in their original description, current
observations tend to indicate that N. parilus avoids faster-flowing
parts of the river.
In
the aquarium
A pair
of fish were obtained from an aquatic outlet during 2007 and
immediately housed in their own tank. The tank dimensions
are 18 x 18 x 15” (45 x 45 x 36 cm, lxbxh) and it holds
approximately 18.5 gallons (70 litres) of water. The tank
is part of the centralized filtration system in the fish house
(approximately 3000 litres of water) and the water parameters
are maintained at approximately pH 4.5 to 5.0, carbonate hardness
(°dKH) undetectable, general hardness (°dGH) undetectable,
Total Dissolved Solids (TDS) at 56ppm and the temperature
held around 79°F (26°C). Water is prepared by passing
tap water through a Heavy Metal Axe (HMA) filter (this contains
a sediment pre filter, and two different activated carbon
based cartridges that will remove chlorine, chloramines and
dissolved metals but does not soften the water or alter the
pH) and then circulating the collected water through moss
peat for a minimum of 24 hours prior to use.
Breeding
tank set-up. Photo by A Wood.
The
tank was decorated with a silica sand substrate to an approximate
depth of 1.5” (3.5 cm), various earthenware caves, a
coconut cave, bogwood and plants (Amazon sword (Echinodorus
sp.), lotus lily (Nymphaea stellata) and Salvinia
natans). Two Nannostomus beckfordi were added
to the tank to act as dither/target fish.
The
fish are fed twice daily using a combination of fresh baby
brine shrimp and a selection of frozen foods that includes
Daphnia, Artemia, bloodworm and Cyclops.
Additional feeds with live Daphnia are also used
when it is available.
During
their settling-in period, both fish spent a lot of time rearranging
the substrate. As opposed to Apistogramma, who use
their mouths to move the substrate, the Nanochromis
used their bodies. The substrate was moved by the fish pushing
along the top of the substrate and slowly building up a pile
of sand in front of them, by repeating this motion, in the
corners of the tank, the substrate now reaches a depth of
up to 3” (7.5 cm).
After
a period of approximately 3 weeks, with the belly of the female
becoming increasingly larger, she took up residence in a clay
cave with an entrance diameter of approximately ¾”
(2 cm). With the use of a flash-light I was able to see some
50 eggs attached to the back of the cave. The eggs developed
for approximately 48 hours before hatching, with the rigglers
remaining inside the cave for a further 5 days. During this
period, the male spent most of his time stationed outside
the entrance to the cave chasing the pencil fish away, the
female would only occasionally appear to take some food and
then retreat back into the cave with the rigglers. When the
female did finally bring the brood out of the cave as free-swimming
fry, it was noticeable that both adults immediately took on
brood-care duties.
Pair
on a tour of the tank with the fry. Photo by A Wood.
The
adults also made full use of the additional caves in the tank
as well, with the fry being escorted from one cave to another
on their daily tours of the tank. Once free-swimming, the
fry were large enough to take the baby brine shrimp and Cyclops
that were being used as part of the routine diet for the adults,
the only difference being that the actual quantity of food
added to the tank was increased. This diet is also currently
being supplemented with banana worms (similar in size to microworm).
With
the fry free-swimming for approximately a week now, the intention
is to leave them with the adults for at least another 3 or
4 weeks, thereafter the juveniles will be moved to their growing-on
tank.
Remarks
When
compared with the South American dwarf and other West African
dwarf cichlids currently in residence in the fish house, the
one fact that stands out is the ability of this pair of N.
parilus to move large volumes of substrate. This just
wasn’t a case of building the sand up around the entrance
to the breeding cave, every inch of the tank floor has been
re-sculpted with the majority of the sand being pushed towards
all four sides of the tank.
Female
guarding free-swimming fry. Photo by A Wood.
As
an introduction to the Nanochromis genus keeping
and breeding this species has been a rewarding experience,
the fun will now begin though as I try to track down the other
members of this genus (and members of the Congochromis
genus) for future breeding projects.
Etymology
Nanochromis
= Latin, nannus – small + Greek, chromis
– a genus of fish which formerly contained many cichlids,
and still used to denote “cichlid” in many generic
names.
parilus = Latin, parilis – equals.
In relation to the similarity in coloration and markings between
the male and female.
References
Lamboj,
A. (2004) The cichlid fishes of Western Africa. Bornheim,
Germany: Birgit Schmettkamp Verlag.
Stiassny, M.L.J. and Schliewen, U.K. (2007) Congochromis,
a new cichlid genus (Teleostei: Cichlidae) from Central Africa,
with the Description of a New Species from the Upper Congo
River, Democratic Republic of Congo. American Museum Novitates
3576, 1-14.
Images
and text remain copyright of the author.
First
published in Cichlidae, 2008, Volume 29, 2 (March). The journal
of the British Cichlid Association.
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