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Effect of stocking size of
the predatory African catfish (Heterobranchus longifilis
V.) on the growth performance of Nile Tilapia (Oreochromis
niloticus L.) in pond culture
Benedict O. Offem*, Gabriel U. Ikpi and Ezekiel O.
Ayotunde
Department of Fisheries, Faculty of Agriculture and Forestry,
Cross River University of Technology, Obubra Campus, Cross
River State, Nigeria.
*Corresponding author: E-mail:
benbeff06@yahoo.com . Tel: 08055930219.
Accepted
22 May, 2009 |
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Overpopulation of tilapia in confined ponds is a major
problem, which causes stunted growth due to shortage of
space and natural food. African catfish Heterobranchus
longifilis, one of the common piscivore to control
tilapia reproduction, has been faulted as having a low
predatory efficiency in certain stocks. A study was
therefore conducted, in which nine ponds with large H.
longifilis + tilapia, small H. longifilis +
tilapia at ratio of 1: 4 (catfish: tilapia) and mixed sex
tilapia (1: 3 male: female sex ratio) breeders were stocked
in monoculture to investigate the influence of the different
size groups of catfish within spawns, on tilapia
reproduction. Three replicate rearing ponds (0.02 ha) were
assigned to each treatment. Final mean weight (Wf), Specific
Growth Rate (SGR), average net and gross yields of the Nile
tilapia indicated higher values for tilapia in polyculture
with large and small H. longifilis than those
stocked in monoculture. Marketable size tilapia constituted
highest percentage in ponds stocked with large H.
longifilis while tilapia in monoculture had the highest
percentage of sub-marketable fish. We therefore suggest that
controlled use of large H. longifilis could be of
immense advantage in terms of the percent of marketable size
tilapia in polyculture.
Key
words:
Effect of growth variation, African catfish, Nile tilapia,
growth performance, marketable tilapia. |
