THA/75/012/WP 21 LENGTH-WEIGHT RELATIONSHIPS OF CULTURED AND WILD Clarias batrachus in Thailand CONTENTS

by

Vijai Srisuwantach and Dhana Yingcharoen

Programme for the Development of Pond Management Techniques
and Disease Control (DoF - UNDP/FAO THA/75/012)
Thailand

National Inland Fisheries Institute
Bangkok, Thailand
1981

PREFACE

The “Programme for the Development of Pond Management Techniques and Disease Control (THA/75/012) was implemented in Thailand during 1979–82 as a joint project by the Department of Fisheries (DoF) and UNDP/FAO. The purpose of the project was to improve DoF support services for Clarias farming through strengthening:

1. the skills of Fisheries staff in aquaculture disciplines such as disease diagnosis and treatment, pond management and extension,

2. the research on solutions for problematical aspects of Clarias culture,

3. the system of relaying problems from the farms to DoF and of transferring improved technologies, and

4. the equipment and facility base of DoF for working on aquaculture problems.

Although the UNDP/FAO participation was structured terminate in August 1981, DoF committed continuation of the project to at least August 1982.

This report is one of several Working Papers prepared on various aspects of the project. A list of titles of reports completed in the series is annexed.

Inquiries concerning the subject matter of any particular report should be directed to the author,

Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.

This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.

CONTENTS

1. INTRODUCTION

2. RESULTS & DISCUSSION

3. REFERENCES

List of Figures:

1. Length-weight relationship of wild Clarias batrachus (after Sidthimunka 1973)

2. Length-weight relationship of cultured Clarias batrachus (after Srisuwantach et. al., 1980)

List of Tables:

1. Length-weight relationships in centimeters and grams of wild Clarias batrachus (after Sidthimunka 1973)

2. Length-weight relationships in centimeters and grams of farmed Clarias batrachus (Srisuwantach et. al., 1980)

3. Relative condition index of farmed Clarias batrachus based on comparison of observed weights of cultured fish and standard weights of wild fish

Length-weight Relationships of Cultured and Wild Clarias batrachus in Thailand¹

Vijai Srisuwantach² and Dhana Yingcharoen³

1. INTRODUCTION

Numerical relationships between length and weight along with condition indices were determined for both wild and cultivated Clarias batrachus in Thailand. The primary data were obtained from pre-existing studies on wild fish by Sidthimunka (1973) and on farmed fish by Srisuwantach, et. al. (1980).

Length-weight relationships were determined by the following equation:

Calculation of the relative condition index (Kn), the ratio of observed weight (W) of fish of a certain length to the calculated or expected weight (W) of fish that long, followed the formula of Le Cren (1951):

¹ Completed as a component study under the “Programme for the Development of Pond Management Techniques and Disease Control (DoF - UNDP/FAO THA/75/012)”.

² Fisheries Biologist, Ecology Unit, National Inland Fisheries Institute, Kasetsart University Campus, Bangkhen, Bangkok 9, Thailand.

³ Fisheries Biologist, Mahasarakam Fisheries Station, Amphoe Muang, Mahasarakam Province, Thailand.

2. RESULTS AND DISCUSSION

Primary measurements were made on wild fish ranging from 7 to 34 cm., and on farmed fish from 5 to 28 cm., in length. In both cases data were grouped in correspondence with one centimeter length classes of the fish.

Regression analyses resulted in the equations

illustrated in Figures 1 and 2, respectively. The computation of expected or standardized weights (), as shown in Tables 1 and 2, was based upon the above equations.

A comparison of the observed weights of farmed fish with standard weights of wild fish shows that cultured Clarias weight an average of about 19% more than their wild counterparts (Table 3).

3. REFERENCES

Le Gren, E.D. 1951. The length-weight relationship and seasonal cycle in gonad weight and condition in perch, Perca fluviatilis. J. Anim. Ecol., 20: 201–219.

Sidthimunka, A. 1973. Length-weight relationships of freshwater fishes of Thailand. International Center for Aquaculture Research and Development, Series No. 3, Auburn University, 25p.

Srisuwantach, V.R. Soungchomphan, and P. Sae-Eng. 1980. Water quality conditions as disease related stressors in Clarias ponds. Ecology Technical Paper No. 3. Ecology Unit, National Inland Fisheries Institute, Bangkok, Thailand. 33p.

Figure 1. Length-weight relationship of wild Clarias batrachus (after Sidthimunka 19873).

Figure 2. Length-weight relationship of cultured Clarias batrachus (Srisuwantach et. al. 1980)

Table 1. Length-weight relationships in centimeters and grams of wild Clarias batrachus (after Sidthimunka 1973).

Table 2. Length-weight relationships in centimeters and grams of farmed Clarias batrachus (Srisawantach et. al. 1980)

Table 3. Relative condition index of farmed Clarias batrachus based on comparison of observed weights of cultured fish and standard weights of wild fish.

The Programme for the Development of Pond Management
Techniques and Disease Control
(DoF-UNDP/FAO THA/75/012)

Reports