Exotic Aquatic Organisms - International Development Research ...

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While it is likely that at the onset, all these species were cultured (Birtwhistle 1931), local
market preferences gravitated towards grass carp, bighead carp and common carp. Silver carp
and mud carp have little commercial value and are not popularly cultured.
None of the Chinese major carps breed naturally in captivity and have neve] established
themselves in local waters. Public stocking programs involving grass carp were first carried out
in the Bukit Merah and Cenderoh impoundments in the early 1960's. Though sporadic reports of
adults of 11 kg being caught were reported, results on the whole were not encouraging (FAO
1965). Bighead carp fingerlings were stocked in the Durian Tunggal, Paya Nakoh and Ampang
reservoirs. The absence of catch data prevents meaningful assessments of the introduction. On
the whole, the release of common carp fry into public waters has been avoided because of their
scouring habits which weaken bunds and increase water turbidity. Common c arp has not
established itself to any major extent. The Chinese carps constitute the mainstay of Malaysia's
freshwater aquaculture industry. In 1986, grass carp, bighead carp and common carp contributed
53.3% by weight and 48.7% by value of Peninsular Malaysia's freshwater aquaculture harvest
(Table 3; Annual Fisheries Statistics 1986).
Rainbow Trout
Rainbow trout (Salmo gairdneri) was first introduced in Brinchang, Cameron Highlands in
1935. Eyed ova, imported from Scotland, were hatched in a now-abandoned facility and the
fingerlings released in the Tenom River.
No details are available on the numbers released, nor how they fared in the new ecosystem.
However, there were unconfirmed reports from villagers living in the area that berried females
weighing about 750 g could be caught from the same river (Somasekheran, pers. comm.). The
program ceased during World War II.
In 1968, Boh Plantations Limited, a tea company in Tanah Rata (also in Cameron
Highlands), began a trGut project for recreational purposes. Fingerlings were released in three
lakes, each of about 3 ha. However, no reliable records on numbers released and. catch were
made. Mature females were frequently caught, but there was no evidence that the fish bred in
local waters. Indeed, maintenance of fish stocks necessitated regular releases of trout fingerlings.
The project was terminated in 1973 mainly for economic reasons. Significantly, disease
problems (whirling disease) in the hatchery were a major impediment to the continuation of the
project.
Tilapia
Tilapia, Oreochromis mossambicus, was first introduced into Malaysian waters from Java
by the Japanese during World War II. O.mossambicus rapidly established itself, particularly in
mining pools, impoundments, and even some coastal areas such as the Johore Straits, bordering
Singapore and Malaysia.
0. mossambicus was initially well received by farmers. In the 1950's it was actively
cultured in ponds and mining pools throughout the country. However, its frequency of
reproduction meant that adults did not grow beyond 200 g. While fish production per unit area
was high they consisted of stunted individuals with little marketability. The fish was also
difficult to eradicate from ponds, particularly undrained ponds and competed with preferred