8342937097

Pertanika 14(1), S7-41 (1991)

COMMUNICATION I

Zooplankton Abundance and Composition in Catfish (Clarias macrocephalus) Ponds.

ABSTRAK

Kelimpahan dan komposisipopulasizooplankton di dałam kolam ikan keli (Clarias macrocephalusl telah dikaji. Kopepoddan rotiferadalah dominan, manakala kladosera hanya merupakan komponenyangminorsahaja. Lawa kopepod adalah dominan, tetapi bagi rotifer, Brachionusquadridentata dan Lecane luna merupakan spesiesyang bilangannyayangpalingbanyak. Diantarakladosera, Macrothrix spinosa merupakan spesiesyangpalingdominan.

ABSTRACT

Zooplankton pnpulation abundance and composition in catfish (Clarias macrocephalus) ponds were studied, Copeponds and rolifers were dominant with cladocerans beinga minor component. Copepod lawae (nauplii) was dominant, but for rolifers, Brachionus quadridentata and Lecane luna were abundant. flmong cladocerans, Macrothrix spinosa was thedominantspecies.

Seberang Perai Tengah (longitude 100° 20 E; latitude5° 25’ N),wereprepared for catfish culture bydrainingand limingwith quicklime-CaO, (7kg/ pond) to remove unwanted parasites, predators and competitors and fertilizing with barn-yard manure (2x20-kgbags/pond) to promote plankton growth. Iwo weeks, after the zooplankton population had been established (Marian 1987), the ponds were stocked with catfish fry (mean size of2.00cm total length, 0.15 g body weight) at the ratę of 1,000 to 1,200 fry per pond. The fry were initiallyfed with Moina but consequently trained to accept prepared diets prior to stocking in ponds. Throughout the study, the fry were fed with commercial feed (32% protein) at the ratę of 3 to 5% body weight. Duringeach sampling period, 10 to 15 fry were caught (about 1/2 before and after feeding) forstomachcontentanalysis.Thecontents were examined under a dissecting microscope and the types of food materials ingested were noted.

Zooplankters were sampled from june 25 to October 15,1987 by randomlyfiltering401of pond water through an 80/u mesh plankton net. Samples were preserved in 10% buffered formalin and later indentified and enumerated using a Sedgewick-Raftercounting celi and standard references (Idris 1983; Karunakaran and Johnson 1975; Fernando and Zankai 1981; Lim and Fernando 1985). Se-lected water quality parameters (dissolved oxygen (DO), temperaturę, pH and conductivity) were measured between 1100 to 1300 h using a Yellow

INTRODUCTION

Fish fry, including the catfish, Clańas macrocephalus,

(Arumugam and Cheah 1987) feed on live zooplankton shortly following yolk sac resorption (Dąbrowski etai 1978). In catfish seed production, live zooplankton (Moina micrura) is used as initial food for fry in hatcheries, prior to subsequent stocking in ponds, to ensure better survival (Arumugam and Cheah 1987; Wembiao et al,

1988). This not only incurs extra production costs in terms of maintaining a large number of fry indoor, but also results in unpredictable seed production due topoorand unreliable zooplankton availability. Even in Penang, wherea thriving Moina tfurruraculture industry exists,shortagesstill occur as catfish farmershave tocompeteagainst tropical fish aquarists for the limited supplyof Moina.

The method of raising fish fry in ponds by utilisingnaturallyoccurringzooplankton hasbeen practised and perfected for species such as carp (Cypńnuscarpio) and striped bass (Moronesaxatiles)

(I ames 1979: Geiger 1983). This technique essen-tially by passes the need for intensive Moinac ulture for feeding fry indoor . This paper discusses zooplankton population dynamics in catfish ponds and the potential forusingthese plankton forcommer-cial catfish fry production .

MATERIALS AND METHODS

Five (6 x 6 x 0.8 m) earthen ponds, situated in