The Biology and Culture of Tilapias

Genus Subgenus Type species Other examples

Tilapia A. Smith (three to six)

Sarotherodon Riippell

T. sparrmanii A. Smith T. rendalli Boulenger

T. zillii Gervais

S. melanotheron Riippell S. galilaeus (Linn.)

S. linnellii (Gnnberg)

Oreochromis Giinther 0. hunteri Giinther

Oreochromis Giinther 0. hunteri Giinther 0. (0.) niloticus (Linn.)

0. (0.) mossambicus (Peters)
   0. (0.) aureus (Steindachner)
   0. (0.) spilurus (Giinther)
   Nyasalapia Thys 0. (N.) squamipinnis (Giinther) 0. (N.) macrochir (Boulenger)


1. (N.) uariabiri (Boulenger)


2. (N.) angolensis (Trewavas)
   Alcolapia Thys 0. (A.) grahami (Boulenger) 0. (A.) alcalicus alcalicus
   = 0. alcalicus grahami (Hilgendorf)
   Neotilapia Regan 0. (N.) tanganicae (Boulenger) None

Danakilia Thys 0. ID.) fmnchetti (Viiciguerra) None

Discussion

GUERRERO: Is it difficult to inter-breed Tilapia species or Sarotherodon species with

Tilapia species such as T. zillii?

TREWAVAS: Have you ever tried to interbreed them?

GUERRERO: No, but the literature suggests incompatibility between Sarotherodon and

Tilapia. One is a mouthbrooder and the other a bottom spawner. I was wondering if it is

difficult to interbreed them. Do you think this is possible or that Tilapia species will

hybridize?

TREWAVAS: T. zillii and T. rendalli do hybridize or they are believed to hybridize in

Lake Victoria where they have both been introduced.

GUERRERO: We have not tried it, but I want to find out if it is possible because of the

differences between the two groups. Tilapia species seem more difficult to interbreed as

opposed to Sarotherodon species.

TREWAVAS: The two genera have never been known to interbreed in nature, nor freely

if they are placed together in one tank, but hybrids have been obtained by artificial fer-

tilization at Tiibingen. Some attempted crosses were unsuccessful, but in one case hybrids

structurally intermediate have been reared to adult size. They were all females.

AVTALION: We have been testing immunological techniques in my laboratory for the

different species of Sarotherodon. All of them are crossreacting antigenically. We could