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International Journal of Aquaculture, 2014, Vol.4, No.16, 96
-
101
http://ija.biopublisher.ca
96
A letter Open Access
Effect of Commercial Feed on Sexual Maturity of Two Tilapia Species
(
Oroechromis niloticus
and
Oreochromis tanganicae
)
Jonathan Nkhoma
1
, Confred G. Musuka
2
1. Matero Residential Area, Muchinga Road, House No. 3262, Lusaka, Zambia
2. The Copperbelt University, School of Natural Resources, P.O. Box 21692, Kitwe, Zambia
Corresponding author Email
International Journal of Aquaculture, 2014, Vol.4, No.16 doi: 10.5376/ija.2014.04.0016
Received: 29 Mar., 2014
Accepted: 30 Apr., 2014
Published: 02 Jun, 2014
Copyright © 2014
Nkhoma and Musuka, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Nkhoma and Musuka, 2014, Effect of Commercial Feed on Sexual Maturity of Two Tilapia Species (
Oroechromis niloticus
and
Oreochromis tanganicae
),
International Journal of Aquaculture, Vol.4, No.16: 96-101 (doi: 10.5376/ija.2014.04.0016)
Abstract
An experiment was conducted for twelve weeks (90 days) in hapas inserted in the semi-concrete ponds to evaluate the
effect of commercial feed on the sexual maturity of two tilapia species,
Oroechromis niloticus
and
Oreochromis tanganicae
. Results
indicated that the final mean body weight was 73.65g for
O. niloticus
and 66.30g for
O. tanganicae
respectively. First maturity in
both species was observed in the sixth week and the smallest fish matured at 34g and 73mm for
O. niloticus
, while for
O. tanganicae
,
it was 42g and 111mm. Length at first maturity was 136mm for
O. niloticus
and 129mm for
O. tanganicae
. Maturity stages were
macroscopically identified into three stages (immature, maturing and mature) and at the end of the trial, 73% of
O. niloticus
and 58%
of
O. tanganicae
were in the reproductive process (mature). The gonadosomatic index (GSI) mean value for
O. niloticus
was higher
than that of
O. tanganicae
. However, there was no significant difference (p>0.05) between GSI values.
Keywords
Commercial feed; Sexual maturity; Effects; Tilapia species;
Oroechromis niloticus
;
Oreochromis tanganicae
Introduction
Tilapia is the common name applied to three genera of
family Cichlidae: (
Sarotherodon
;
Oreochromis
and
Tilapia
) including about 70 species (Meyer, 2002).
Tilapias are the second most important farmed fish
after carp (El-Sayed, 2002) that is one of the most
important food fish in the world, especially in Europe
and Asia (Currie, 1991). Carp production is growing
rapidly in Asia, increasing from 5.537 million t in
1990 to 16.313 million t in 2001, an annual growth
rate of 11 per cent (Dey et al., 2005).
In Zambia, as in many parts of the world wild
Oreochromis species
are the major cultured tilapia
species because they are readily acceptable by
consumers throughout the country (Mudenda, 2004).
They are good candidate species for pond culture due
to their high adaptability to a wide range of
environments, tolerance to harsh conditions (low
water quality and high stocking densities), handling,
ease reproduction and fast growth (El-Sayed, 2002).
One of the major problems in tilapia culture, is the
tendency of females to mature and reproduce at small
sizes (Popma and Lovshin 1995).
In that study authors
observed that, in tilapia sexual maturity is a function
of
age
,
size
, and environmental conditions.
Furthermore, they reported that tilapia populations in
large lakes mature at a later age and larger size than
the same species raised in culture ponds (Popma and
Lovshin 1995). For instance,
O. niloticus
matures at
about 10 to 12 months and 350 to 500g in several East
African lakes but the same population culture in ponds
will reach sexual maturity at an age of 5 to 6 months
and 150 to 200g (Popma and Lovshin, 1995). A study
conducted by Hepher and Pruginin (1982) observed
that some tilapias species can also reach sexual
maturity in 3 to 6 months, and spawn before they
reach a marketable size when grown in ponds and
controlled cultured conditions. When growth is slow
in culture ponds, sexual maturity will be delayed by a
month or two but fish may spawn at weights as low as
20g (Mair and Little, 1991). According to Hepher and
Pruginin (1982), their early maturation and prolific
“wild” spawning produce such large number of small
fry as to cause stunting of the entire tilapia population
and often of other species in the pond. Similarly,
Baroiller and Toguyeni (1996) reported that the early
sexual maturity of
Oreochromis
species leads to
overcrowding and stunting resulting in limited
economic yields for fish farms since energy is directed
towards reproduction instead of somatic growth.