Fish, Tanks and Ponds


Fish, Tanks and Ponds
A comprehensive guide to fish

Nimbochromis venustus

Venustus

Nimbochromis venustusNimbochromis venustus
Photos by Andy Rapson  and Michelle Stuart

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:

Nimbochromis: Latin, nimbus = stormy, rainy + Greek, chromis, it has dark clouded melanic blotches on the body
venustus: From the Latin "venustus" = beautiful, graceful, elegant

General Notes:

Contrary to popular opinion Lake Malawi contains alkaline but relatively soft water with a hardness of just dGH 4 - 6° and a slightly higher alkalinity of KH 6 - 8° the water in Lake Malawi contains negligible levels of salt.

Unlike the Mbuna of Lake Malawi Nimbochromis venustus lives in open water where there is a sandy substrate. It is an ambush predator and will often lay motionless partially buried and wait for a prey item to come and investigate what appears to be a dead fish, once the prey item is close enough the trap is sprung and the N. venustus grabs its inquisitive meal.

In the aquarium N. venustus is fairly peaceful with fish which are too big to be considered as food.

Compatibility:

Peaceful with fish of a similar size.

Feeding:

Nimbochromis venustus feeds predominantly on smaller fish and in the aquarium smaller fish will be regarded as food.

In captivity they are unfussy feeders and will accept a range of suitably sized live or frozen food as well as pellets and even flake.

Note it is illegal in the UK to use live vertebrates as food, this includes fish.

Sexing:

Adult males are larger than adult females and only the males have the blue head colouration.

Breeding:

N. venustus is a maternal mouth brooder. The male will select and prepare a breeding site and then display to all passing females, if one is ready to spawn the pair will circle each other over the chosen site and the eggs will be laid and fertilised as they circle. Only the female will pick up the eggs and keep them in her mouth until the fry are ready to live independently.

Some breeders advocate removing the eggs from the female and brood them artificially but to my mind N. venustus mums have been doing a great job for tens of thousands of years so just let them get on with it.

Wild status:

Fairly common throughout both lakes and under no immediate threats.

Further Information:

 

Information at a glance

H: 7.6 - 8.4
dGH: 7.8 - 8.5
Temperature: 23 - 28°C (74 - 82°F)
Lighting: Not critical
Diet: Carnivore
Size: 20cm (8in)
Min tank size: 450 litres
Difficulty level: Intermediate
Aquarium type: Malawi community
Swimming level: All levels

Distribution and habitat

distribution map for Nimbochromis venustus

Origin: E Africa, Endemic to Lake Malawi and Lake Malombe.

Habitat: Juveniles in shallow open water or near to rocks with a sandy substrate. Adults found at 15 - 20m deep in open water with a sandy substrate.

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Cichlidae
Genus: Nimbochromis
SpeciesN. venustus,

Common name: Venus cichlid

Synonyms:

 Haplochromis venustus,
Cyrtocara venusta,
Haplochromis simulans