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Biological Control of Harmful Zooplankton by the Spawns of Carla Catla in Nursery Fish Ponds

M.A. Islam
Limnology Laboratory, Department of Botany, Rajshahi University

A.H. Chowdhury
Environmental Science Discipline, Khulna University, Bangladesh

Abstract/ Executive Summary:

Eradication by biological control method of some zooplanktons which are harmful to fish hatchlings has been studied in five nursery fish ponds from 1992 to 2004 in Rajshahi, Bangladesh. Spawns of Carla catla, Labio rohita, Cirrhina mrigala, Cyprinus carpio and Puntius gonionotus were introduced separately in each pond to eradicate the harmful zooplankton (Copepoda and Cldocera) instead of using poisons before introducing the fish hatchlings into the ponds. As a result all the Copepoda and Cladocera were found to be completely eaten up in Pond 1 by the spawns of Catla calla but in Ponds 2, 3, 4 & 5 the harmful zooplankton were not eaten by spawns of Labio rohita, Cirrhina mrigala, Cyprinus carpio and Puntius gonionotus. It indicates that spawns of Carla catla can be used to eradicate the harmful zooplankton in nursery fish ponds.

Keywords: Nursery fish pond, Harmful zooplankton, Catla catla, Biological control.

Location: Meherchandi, Rajshahi, Bangladesh

Start Date: 00-00-1992

End Date: 00-00-2004

Program Area: Animal Health and Management

Commodity: Plankton, Catla

Objectives:

The present study deals with the eradication of some zooplankton harmful to fish hatchlings by biological control method in nursery fish ponds in Rajshahi, Bangladesh.

Methodology:

Fortnightly samplings were carried out in five nursery fish ponds at Meherchandi, Rajshahi, Bangladesh from 1992 to 2004 (April to July/ year). These ponds (Ponds 1, 2, 3, 4 & 5) are rectangular in shape covering an area of 1333m2 each with an average depth of 0.8 - 1.5 m. These ponds are located at a distance of 100-500 meters from each other. All the ponds are moderately treated with lime (2 kg/decimal/yr) and cow dung (0.3 kg/decimal/day). Every experiment had completed in two different steps. In step -1, juveniles of Catla (Carla catla) were used for seven days in all the study ponds (Ponds 1, 2, 3, 4 & 5) to eradicate Copepoda and Cldocera from all study ponds before introducing the fish hatchlings into all the ponds. In step-2, hatchlings of Calla were introduced in Pond 1 for the eradication of Copepoda and Cldocera instead of using poisons; but other four ponds (Pond 2, Pond 3, Pond 4 & Pond 5) were always kept under control conditions by introducing the hatchlings of Rui (Labio rohita), Mrigal (Cirrhina mrigala), Common carp (Cyprinus carpio) and Punti (Puntius gonionotus) separately in each pond. All juveniles of Catla were removed from all study ponds before starting the step-2 of the experiment. In each pond hatchlings were introduced once a month. This method was repeated 52 times during the period of study from 1992-2004 (each year 4 times). Water samples were collected by using 250 ml glass stoppered bottle. Temperature was noted by a centigrade thermometer. Transparency was measured by a Secchi disc. pH was determined by a digital pH meter (pH ep Hanna Instrument). All chemical parameters were measured by following APHA (1989). Zooplankton samples were collected by using Plankton net of No. 20 silk bolting cloth of mesh size 0.076 mm. After collection the plankton materials were transferred into glass bottle and preserved permanently in Transeau's solution (Transeau 1951). Zooplankton abundance was measured by using a Sedge Wick Rafter Counting Chamber (Welch 1948) and expressed in unit/l. Zooplankton was identified with the help of relevant literature (Edmondson 1966 & Tonapi 1980). Ponds were netted several times with synthetic net of fine mesh size, for the withdrawal of insects prior to introducing the hatchlings into ponds.

Source of Information: South Asian J. Agric. 2009. 4 (I &2): 59-62 ISSN 1991-0037

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The present study reveals that the biological control of zooplankton e.g. Copepods and Cladocerans which are harmful to the spawns of culture fishes can be achieved by using the spawns of Catla in nursery ponds but hatchlings of other fishes i.e Rui, Mrigal, common carp and Punti can not eradicate the Copepods and Cladocerans. The present finding of this study is indicating that the fish farmers can easily use the Catla catla to eradicate the harmful zooplankton of their nursery fish ponds, as a result pesticides using to be reduced and environment-friendly fish culture practice to be enhanced

Knowledge Management: Journal