The study deals with the length-weight relationship and relative condition factor (Kn) of

mahseer, Tor putitora reared for 150 days in ponds. The logarithmic form of equation for

the relationship was found to be logW = -1.727+2.875logL or W=O.Ol875U·875

• The

graphical presentation of the parabolic and logarithmic forms showed respectively the

curvilinear and linear relationships between length and weight of the fish. The mean

value (±sd) of relative condition factor was found to be 0.95±0.12. The exponential value

'b' was found to be 2.96 and the coefficient of correlation 'r' was 0.965, which showed

strong and highly correlated relationships between length and weight of the fish

Dewan, S.

Hossain, M.A.

Hussain, M.G.

Islam, M.S.

Mazid, M.A.

Aquatic Commons

Bangladesh] Fish. Res., 6(2), 2002: 159-164 
Length-weight relationship and relative condition factor of 
pond-reared mahseer, Tor putitora(Ham.) 
M.S. Islam*, S. Dewan, M.G. Hussain1, M.A. Hossain1 and M.A. Mazid1 
Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh 
3Bangladesh Fisheries Research Institute, Mymensingh 2201, Bangladesh 
*Present address & Corresponding author: Division of Applied Biosciences , Faculty of Fisheries, Graduate 
School of Agriculture, Kyoto University, Kyoto 606-8502, Japan 
Abstract 
The study deals with the length-weight relationship and relative condition factor (Kn) of 
mahseer, Tor putitora reared for 150 days in ponds. The logarithmic form of equation for 
the relationship was found to be logW = -1.727+2.875logL or W=O.Ol875U·875 • The 
graphical presentation of the parabolic and logarithmic forms showed respectively the 
curvilinear and linear relationships between length and weight of the fish. The mean 
value (±sd) of relative condition factor was found to be 0.95±0.12. The exponential value 
'b' was found to be 2.96 and the coefficient of correlation 'r' was 0.965, which showed 
strong and highly correlated relationships between length and weight of the fish. 
Key words: Length-weight relationship, Tor putitora 
Introduction 
Mahseer (Tor putitora) is an important cyprinid fish famous for its lucrative 
appearance and delicious taste and is highly popular among people of the Southeast 
Asian countries, particularly in the Indian subcontinent, including Nepal (Mirza 1993 
and 1994a&b, Nath et al 1994, Shrestha 1994). There are seven species of mahseer in 
Southeast Asia but only two species, namely, Tor tor and Tor putitora are reported in 
Bangladesh. They are distributed in the hill streams of Sylhet, Mymensingh, Dinajpur 
Districts and the Kaptai reservoir of Rangamati (Rahman 1989). Although reported to 
occur in some areas of Bangladesh (Ahmed 1969, Chandra and Haque 1982a&b, Rahman 
1989, Azadi et al 1990) it has not yet been possible either to develop a commercial 
fishery of mahseer in its natural habitat or to introduce the fish into commercial 
aquaculture of Bangladesh. Recently, the fish is gaining special attention because of its 
rapid disappearance from natural environment. To establish the fish in its natural 
habitat, scientists are becoming increasingly concerned with the biology and 
management of the fish. 
Length-weight relationship is a very important aspect of the biology of any fish, 
particularly when the fish is to be reared commercially. Due to variations in season, food 
M.S. Islam et al. 
composition and multiple spawning, growth fluctuations are more common in fishes of 
tropical and subtropical waters (Lagler 1956). However, in most fishes, length and 
weight bear a specific relationship from which the physical well being of a fish can be 
ascertained for a given body at a given time (Doha and Dewan 1967). The study of 
length-weight relationship in fishes helps to determine the mathematical relationship 
between the two variables and to calculate the variation from the expected weight for 
length of individual or groups of fishes (Le Cren 1951). 
Many works have so far been undertaken on the length-weight relationships of 
different species of fishes. However, very few reports are available on the length-weight 
relationship of fishes under the genus Tor. Dasgupta (1991) studied the length-weight 
relationship of Tor putitora from Meghalaya, India and Javaid et a1. (1992) from 
Islamabad, Pakistan. Study on the length-weight relationship of Tor fishes in 
Bangladesh is also of considerable importance. In the present study, attempt has been 
made to establish the length-weight relationship of pond-reared Tor putitora. 
Materials and methods 
Hatchery produced fingerlings of mahseer with average total length of 11.80 em and 
body weight of 12.50 g were reared with supplementary feeding under fertilized 
condition for a period of 150 days in earthen ponds of Bangladesh Fisheries Research 
Institute, Mymensingh. At harvest, average total length and weight were 20.25 em and 
85.60g, respectively. Fish were sampled fortnightly and total length and weight of 
individual fish were recorded. Therefore, large volume of data on length and weight of 
fish at different ages and sizes were obtained. 
:Total length (from snout to the end of the tail) of each individual fish was measured 
to the nearest centimeter (em) on a scale. Weight was taken to nearest gram (g) on a 
sensitive digital electronic balance. For calculation, the data were divided into 12 class 
intervals and the frequency for each class interval was found out. The regression line of 
length-weight relationship was drawn by plotting the body weight data against the total 
length data. Again, all the mid-values (em) of the class intervals and the corresponding 
average weight (g) were converted to base log10 to obtain straight-line relationship 
between length and weight. The non-linear equation W=aLb representing the length-
weight relationship in fishes as proposed by Le Cren (1951) was used, which is the linear 
equation of the type Y = a + bX, where Y = logW, 'a' and 'b' are constants and X = 
logL. The constants 'a' and 'b' were estimated by least square method. The regression 
coefficient (b) and correlation coefficient (r) were determined by a programme scientific 
calculator. 
The relative condition factors were also calculated separately for each class interval 
by the following formula (Le Cren 1951): 
160 
w 
Kn= 
1\ 
w 
Where, Kn = relative condition factor 
W = observed body weight (g) 
1\ 
W = calculated body weight (g) 
1\ 
W was calculated by using the following formula: 
1\ 
W =antilog (log a+ n logL) 
Results and discussion 
Length-weight relationship of mahseer 
The results of the length-weight relationships are shown in Table 1. The 
logarithmic form of equation obtained for the length-weight relationship of Tor putitora 
was represented by logW = -1.727 + 2.875 logL, or, W = 0.01875 L 2·875• The parabolic 
and logarithmic relationships between the length and weight are given in Figs. 1 and 2. 
The length-weight relationship in parabolic equation usually lies between 2.5 and 4.0 
(Hile 1936). In a typical fish that maintains constant shape, 'b' will be 3.0, i.e., growth is 
isometric (Andrade and Campos 2002). However, the condition of fish is subject to 
variations with a number of factors including reproductive cycles and availability of 
foods (Thompson 1943, Rounsefell and Everhart 1953, Lagler 1956, Morato et al. 2001). 
Such variations may also be related to the environmental factors and the age and the 
physiological state of the fish (Brown 1957). Dasgupta (1991) reported that the length-
weight relationship of mahseer, Tor putitora follows the cube law, indicating an 
isometric pattern of growth. He also stated that the condition factor 'K' and the relative 
condition factor (Kn) vary with season, age of the fish and feeding intensity. J avaid et al 
(1992) determined the value of regression slope to be b = 2.93 in case of Tor putitora. 
The variations in results obtained in the present study might be due to the factors 
mentioned above. 
The value of the correlation coefficient 'r' recorded in the present study was 0.965 
(Table 1), which indicates strong and highly correlated relationship between length and 
weight of the fish. Roy (1987) also observed strong and highly correlated relationship 
between length and weight in three species of carps. 
161 
M.S. Islam et al. 
Table 1. Length-weight relationship and relative condition factor of T.putitora 
Class Mid value Frequency Av. Wt. (W) logL logW Calculated Kn Av r 
intervals (TL) (f) (g) {\ 
(em) wt. cW) Kn 
12-13 12.5 10 25.58 1.097 1.408 33.46 0.76 
13-14 13.5 12 29.84 1.130 1.475 37.23 0.80 
14-15 14.5 16 33.90 1.161 1.530 41.17 0.82 
15-16 15.5 21 35.75 1.190 1.553 45.22 0.87 
16-17 16.5 23 54.90 1.217 1.739 47.93 1.15 
17-18 17.5 27 62.76 1.243 1.798 56.66 1.11 
18-19 18.5 29 69.65 1.267 1.843 66.16 1.05 
19-20 19.5 35 76.38 1.290 1.883 76.74 0.99 
20-21 20.5 30 85.82 1.312 1.934 88.43 0.97 N ,.... 
21-22 21.5 12 97.03 1.332 1.987 100.60 0.96 0 +I 
22-23 22.5 7 109.56 1.352 2.039 114.45 0.95 V"'\ \0 a.. a.. 
23-24 23.5 3 121.80 1.371 2.086 129.36 0.94 0 0 
The graphical representation of regression lines for length-weight relationships of 
the fish indicated that the weight of fish has curvilinear relationships with total length. 
The regression lines obtained by plotting the log data (1og length against log weight) 
were straight, which indicate that the log length of the fish has linear relationship with 
log weight. These findings agree with that reported by Shrivastava and Pandey (1981), 
who observed straight-line relationship in carps. The relative condition factor (Kn) 
ranged between 0.76 and 1.15 with a mean (±sd) value of 0.95±0.12. The Kn values 
recorded for the fish indicate good condition of the fish. Kn values were found to show 
an increasing trend with higher age groups but a decreasing trend was observed with 
further increase in age (Fig. 3). Le Cren (1951), Shafi and Mustafa (1976) and Azadi et al 
(1991) also reported variations in Kn values with different age and size groups of fishes. 
Tor fishes are poorly smdied group among the carps. Little is known about the 
different aspects of biology and culture potential of this fish. The present study indicates 
an isometric pattern of growth and a strong and highly correlated relationship between 
length and weight of the fish. However, it is recommended that the length-weight 
relationship and condition of the fish should be studied further both for culmred and 
wild populations. 
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(Manuscript received 5 May 2001) 
164 


Length-weight relationship and relative condition factor of

pond-reared mahseer, Tor putitora(Ham.)

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Length-weight relationship and relative condition factor of pond-reared mahseer, Tor putitora(Ham.)

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