The Biology and Culture of Tilapias

Tilapia Hybridization

International Center for Aquaculture

Auburn University

Auburn, Alabama 36844

U.S.A.

LOVSHIN, L.L. 1982. Tilapia hybridization, p. 279-308. In R.S.V. Pullin and

R.H. Lowe-McConnell (eds.) The biology and culture of tilapias. ICLARM

Conference Proceedings 7, 432 p. International Center for Living Aquatic

Resources Management, Manila, Philippines.

Tilapia hybrids have demonstrated impressive growout potential using a

wide variety of commercial and agricultural by-products as diets. The oppor-

tunity of stocking all-male tilapias without prior manual sex separation has

tantalized fish culturists for many years. However, all-male tilapia hybrid

culture has yet to be accomplished on a large commercial scale. Problems of

maintaining pure genetic strains of broodstock and technical problems of

producing commercial numbers of all-male tilapia hybrids have limited

expansion. Research is needed to determine systems for mass producing

all-male tilapia hybrid fingerlings.

When the technology for producing all-male tilapia hybrids on a commer-

cial scale becomes available, culture will likely be limited to governments and

wealthy farmers with moaey to build properly designed hatchery facilities

and to hire trained biologists to manage the hatchery.

Introduction

Biologists working with tilapias have been experimenting for many years
with methods to reduce or eliminate uncontrolled spawning in growout
ponds. One method found to reduce tilapia reproduction is by hybridizing
two species of tilapias resulting in offspring that are either all-male or con-
tain a high percentage of males. This paper will attempt to determine the
state of hybrid tilapia culture in the world today and to present the major
strengths, limitations, and needs of this culture system. Unless otherwise
noted, the female parent will appear first in all hybrid crosses.
Hickling (1960) was the first to report the possibility of producing all-male
hybrids. He was attempting to produce a sterile hybrid with superior growth
potential when he crossed Sarotherodon mossambicus with Sarotherodon
hornorum (this fish was originally classified as T. mossambica (Zanzibar
strain). To Hickling's surprise and satisfaction, crossing the female S. mos-
sambicus with the male S. hornorum produced all-male hybrids. The hybrids
were not "mules" or sterile but were fertile and capable of reproducing.
These results stimulated other scientists to hybridize tilapias in the hope that