Tilapia guinasana

Namibia. Endemic to Lake Guinas, but has also been introduced into Lake Otjikoto and some reservoirs in Namibia for conservation purposes. It has also been recorded in underground rivers.

Lake Guinas (and also Lake Otjikoto) is a sink hole lake containing very clear water. The fish are found around the rocky walls of the lake, where they defend small ledges as breeding territories. The lake was formed by a subterranean cave collapsing in on itself and is over 100 metres deep.

120 ∗ 30 ∗ 30 cm48 ∗ 12 ∗ 12 in - ~108 litres~29 US gal.

The fish will exhibit the most natural behaviour if maintained in a biotope setup. This should contain piles of rockwork built up around the back and sides of the aquarium and bright lighting to encourage algal growth. A substrate of sand is the most suitable. Plants are not a feature of this species' natural environment and will most likely be eaten.

Temperature: 19 – 25 °C66 – 77 °F.

pH: 7.0-7.8

Hardness: 10-15°H

In nature, it mainly feeds on algae and organisms found within it by grazing the rocky walls of the lake. A low protein diet is therefore essential in keeping the fish in good health. spirulina flake, nori and blanched spinach are all suitable, and these can be supplemented with occasional small feeds of live or frozen brineshrimp/bloodworm etc.

Can be kept with larger African tetras such as Congo tetras but does best in a species tank to allow the best possible chances of a successful spawn. The fish pay little attention to conspecifics, but become territorial when breeding.

Difficult to sex. The only reliable method is to examine the genital papillae of the fish but this is for experts only. The papilla is pointed in the male and rounded in the female.

Possible. Bi-parental substrate spawner. In nature, the fish will often choose a ledge on the rocky walls of Lake Guinas on which to spawn. In the aquarium, a flat rock or even an open area of substrate will suffice. The aquarium should be set up as described above, with the provision of the aforementioned features to act as potential spawning sites. The water should have a temperature of 22 – 25 °C72 – 77 °F and a pH to the slightly alkaline side of neutral. As the fish are difficult to sex, try and obtain a group of 6-8 fish and allow things to develop naturally. Condition the fish on a high quality diet containing a high percentage of vegetable matter.

The fish will either spawn on a flat rock surface or in a shallow pit, excavated from the substrate. Up to 200 eggs may be laid and these are protected by both parents, with the female generally staying close to the brood and the male defending the territory. The pair may move the eggs to other pits they have dug or into crevices between rocks several times before the fry become free swimming. This usually occurs in 10-14 days, and both parents proceed to shepherd the brood around the aquarium, defending them against all-comers. Brood care is quite extended and the fry can be left with the parents for several weeks post-spawning. The fry will accept brine shrimp nauplii but should also be offered greenstuffs.

Rare in the hobby, this species is unfortunately considered critically endangered in the wild. The lake in which it is found is receiving less groundwater than it once was, due to extraction of water for agriculture. Even if this were not the case, the species is found over such an enclosed range that it would still be at extreme risk. All attempts at captive breeding are therefore to be encouraged, with care being taken to keep the different lines pure.

Interestingly, as there are no natural predators of the fish in Lake Guinas the fish exist in many distinct colour forms. Unsurprisingly, in the introduced populations this dichromatism has not developed.