Aquatic Store Directory
Keeping & Breeding Nanochromis parilus Roberts & Stewart, 1976
Written by Administrator
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.
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.
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.
Congo (Brazzaville) and the Democratic Republic of Congo, around Kinshasa.
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.
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.
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.
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.