Fish, Tanks and Ponds


Fish, Tanks and Ponds
A comprehensive guide to fish

Pseudotropheus cyaneorhabdos

Pseudotropheus cyaneorhabdosPseudotropheus cyaneorhabdos
Photos by Andy Rapson

A little about Lake Malawi

Lake Malawi is often quoted as containing hard alkaline water. This isn't so, the water in Lake Malawi is relatively soft when compared with other large lakes in the African Rift Valley.

  • The average dGH is 7 - 9
  • The average pH is 7.8 - 8.5
  • The average temperature varies throughout the year from 23 - 28°C

The difference in pH is accounted for by differing levels of CO2 found in the water. Deeper water and sheltered bays may have higher levels of CO2 and so the pH will be lower. Wind swept shallow water will have a better gas transfer at the surface and so will contain less CO2 making the pH higher.

Lake Malawi contains approx only one third of of the dissolved mineral level of nearby Lake Tanganyika and so chemically the two lakes are very different and this is one reason why it is a bad idea to keep fish from the two different lakes in one aquarium.

Etymology:

Pseudotropheus: Greek, pseudes = false + Greek, tropaion = defeat, a memorial of a fighting war, trophy; because of their specialized teeth were such an obvious feeding adaptation .

General Notes:

Pseudotropheus cyaneorhabdos is one of the cichlids which as a group are called Mbuna which is an African word meaning rock dweller. All the Mbuna come from just one lake in the East African Rift Valley, Lake Malawi. The Mbuna are mostly blue or yellow with just a few other colours but they make a very striking display when housed in a biotope aquarium. All Mbuna are aggressive with most of the Melanochromis genus being among the most aggressive.

Early attempts to keep these fish failed because fish keepers tried to house them as pairs which resulted in the female being injured or killed. All Mbuna need to be very carefully stocked in an aquarium. If there are too few fish, one of the larger males will become hyper-dominant. With an over crowded tank the fish will all be stressed and the water quality will be difficult to maintain. Somewhere in-between the two is the magic number where the fish will live peacefully together without being stressed. It is also worth keeping in mind that this is likely to be a dynamic situation rather than a permanent one and intervention may be needed at some point in order to keep things peaceful. This is especially true where Pseudotropheus are concerned.

Try an initial stocking level of 1 inch of fish per 8²in of water surface (around four average Mbuna per sq foot of floor space). This seems a lot by normal stocking standards but it is important to do this. Obviously tank maintenance and filtration have to be stepped up to cope with this too. Even with this stocking level only one male per species should be housed in the same aquarium with three or four females per male, doing this will reduce the risk of hybrids being produced.

All Mbuna need alkaline water, it is often said that Lake Malawi's water is hard and alkaline, this isn't really the case, the water is alkaline but it isn't particularly hard especially when compared to neighbouring Lake Tanganyika. is one of the cichlids which as a group are called Mbuna which is an African word meaning rock dweller. All the Mbuna come from just one lake in the East African Rift Valley, Lake Malawi. The Mbuna are mostly blue or yellow with just a few other colours but they make a very striking display when housed in a biotope aquarium.

Compatibility:

Pseudotropheus cyaneorhabdos can only be kept successfully in a mbuna community with other mbuna. Keep just one male with three or four females in order to spread the males attention from just one female.

Feeding:

Wild Pseudotropheus cyaneorhabdos feed on small aquatic inverts and zooplankton. In captivity they are bold, unfussy feeders which will accept virtually everything on offer. Ideally their diet should include things like live or frozen blood worms, daphnia, cyclops and brine shrimps along with a good quality flake or suitably sized pelleted food.

Sexing:

Difficult, both sexes have very similar colouration. But when adult the males are bgger.

Breeding:

Pseudotropheus cyaneorhabdos is a mouth brooder, the male will select a small territory and prepare it and then begin displaying to any passing female. If the female is ready to spawn she will follow the male to his territory and the pair will begin to circle each other. The eggs are laid and fertilised as the pair circle and then the female will break away and pick up the eggs in her mouth where they are stored in a special brood pouch. The female will then return to the male and the process repeated until all the eggs have been laid. The female will then seek out a quite spot and keep a low profile for the next month until the fry are ready to be released. If left to her own devices one or two fry may grow up to adulthood even in a mbuna community but if you want to raise a brood then the female will need to have a tank of her own.

After spawning has taken place leave the fish as they are for a few days in order to allow the female to bond with the eggs or she may spit them out if caught to soon, but don't leave it to long because there is a chance that the fry may be harmed in the transfer if they have hatched, two to three days is about right to make the transfer. Don't offer any food to the brooding mother because she won't eat while brooding.

Once the fry are released they are fully independent and quite advanced for fry due to their good start in life. Broods are quite small compared to other cichlids but the fry of Pseudotropheus cyaneorhabdos are comparatively large and if grown on in a rearing tank most will make it to adulthood.

Try to avoid inbreeding, don't buy all your stock from a single breeder because if you do you will be breeding closely related fish with each other and then the next person will come along and buy all of his stock off you which very quickly over just a few generations lead to inbreeding problems.

Wild status:

The IUCN red List of endangered species lists Pseudotropheus cyaneorhabdos as being vulnerable. This species is only found at one location in Lake Malawi and it is collected for the aquatic trade.

Further Information:

Some breeders insist on trying to extract the eggs from the female and raise them artificially, this risks injuring the female and there really is no advantage to raising the eggs this way, female Mbuna have been making a great job of it for thousands of years so it is best just to let them get on with it.

Information at a glance

H: 7.6 - 8.4
dGH: 7.8 - 8.5
Temperature: 23 - 28°C (74 - 82°F)
Lighting:
Diet: Omnivore
Size: 20cm (8in)
Min tank size: 450 litres
Difficulty level: Intermediate
Aquarium type: Community
Swimming level: All levels

Distribution and habitat

distribution map for Pseudotropheus cyaneorhabdos

Origin: E Africa, Likoma Island, Lake Malawi (endemic)

Habitat: Shallow water with rocky outcrops and stony rubble.

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Cichlidae
Genus: Pseudotropheus
SpeciesP. cyaneorhabdos,
(Bowers & Stauffer, 1997)

Common name: None

Synonyms:
Melanochromis cyaneorhabdos