20+ Million Readerbase
###### Indexed In

###### Useful Links

###### Share This Page

###### Recommended Webinars & Conferences

### 6th World Congress on Emerging Trends in Science, Engineering and Technology

Amsterdam, Netherlands
### 8th International Conference on Oceanography and Marine Biology

Budapest, Hungary
### 7th Annual Congress on Soil, Plant and Water Sciences

Dublin, Ireland
###### Journal Flyer

###### Open Access Journals

- SafetyLit
- RefSeek
- Hamdard University
- EBSCO A-Z
- OCLC- WorldCat
- Publons

- Agri and Aquaculture
- Biochemistry
- Bioinformatics & Systems Biology
- Business & Management
- Chemistry
- Clinical Sciences
- Engineering
- Food & Nutrition
- General Science
- Genetics & Molecular Biology
- Immunology & Microbiology
- Medical Sciences
- Neuroscience & Psychology
- Nursing & Health Care
- Pharmaceutical Sciences

Research Article - (2014) Volume 17, Issue 1

*
*

**Keywords:**
Mullets; Length-weight relationship; Condition factor; Relative condition factor

Fishes of the family Mugilidae are commonly known as “mullets” or “grey mullets”. This family includes 18 genera and 81 species [1,2]. Commonly found in marine and brackish waters or estuaries at 20 m depth. Some species spend their whole lives in fresh water habitats, i.e., Liza abu. In Pakistan, Bianchi [3] described 3 genera and 12 species, while Fahmida [4] identified the eight mullet species on Karachi Coast, e.g., *Mugil cephalus, Valamugil seheli, Valamugil speigleri, Liza carinata, Liza parsia, Liza subviridis, Liza abu and Liza vaigiensis.*

Many researchers have published their reports on length-weight relationship (LWRs), condition factor (K) and relative condition factor (Kn) of the mugilid species such as, Length-weight relationship (LWRs) data of two mullet species, i.e., *Liza macrolepis* and *Mugil cephalus* from the different regions of world such as, near the coast of Mandapam (India), Negombo lagoon (Sri Lanka), Bonny estuary (Nigeria) and southwestern coast of Taiwan was given by Luther [5], Wijeyaratne and Costa [6] Aleleye-Wokoma et al. [7] and Chu et al. [8]. Karna et al. [9] described the LWRs of *V. speigleri* from Chilika lagoon of India. Though the information regarding to the LWRs of mullet species from Pakistan coast was still scarce, however, Abbas [10] studied the LWRs of Liza carinata from Bhanbhore tidal backwaters along the Sindh coast of Pakistan. Hence, the main purpose of this study was to calculate the length-weight relationship, condition and relative condition factors for the four selected mugilid species in order to observe their growth pattern and physical or heath conditions at Karachi coast.

**Samples collection**

A total of 246 specimens of the four species of family Mugilidae were collected monthly from the landings at Karachi fish harbour, during the period of April 2010 to December 2011. The total catch contained 69 individuals of *Liza melinoptera, 79 Valamugil speigleri, 62 Liza macrolepis and 36 Mugil cephalus,* respectively. In Pakistan, these fishes are caught mainly with gillnets, castnets, liftnets and beach seines as reported by Bianchi [3]. Each specimen was identified to species level in the field as well as in laboratory by using the FAO field guide [3,11]. Total length (TL) of each specimen was measured in centimeters from the tip of snout to the end of caudal fin using measuring board. Weight (W) for each fish sample was noted on digital balance. Then fishes were immediately preserved in 10% formaldehyde solution for about one week, and after that stored in 70% ethanol for long time preservation.

**Length-weight relationship (LWRs)**

Length-weight relationship was calculated separately for male, female and combined sexes of each selected mullet species. The lengthweight relationship was calculated by using cubic law suggested by Le Cren [12] as follows;

(1)

Whereas, W is the wet weight in grams, L is the total body length in centimeters; a is the intercept and b is the exponent or regression slope. In order to confirmed that whether length and weight were linearly related with each other, the slope of the regression line (b) was subjected to t-test at 5% significant level (p<0.05) to test the null hypothesis Ho: b1=0 against the alternate hypothesis Ha: B1 ≠ 0 by using following model 2 as follows;

(2)

Where b1 is the slope of regression line, S_{xx} is the notation used in regression; Se is the standard error of estimate, which can be calculated by following model 3 as follows;

(3)

Where SSE is the sum of square error. The values of SSE can be calculated by model 4 as follows;

(4)

Where the values of S_{xx} was calculated by using model 5 as follows;

(5)

Where x is the independent variable.

But the parameters a and b were estimated by the least square regression method for combined and separate sexes, so it is more better to use log transformation data than the regression equation obtained from the model 1 in order to make the relationship linear. So, the above model 1 was logarithmically transformed into model 6 as suggested by Anibeze [13] was as follows;

(6)

Where b is an exponent or allometric growth coefficient usually has value between 2.5 to 4.0. Therefore, the values of an exponent b of the length-weight relationship was tested for departure from its ideal value, that is b=3, when growth is isometric. Hence, LWRs (logarithmic) was used to check whether the growth was positive or negative allometric.

In order to confirm that whether the b-values obtained in the linear regression analysis were significantly different from the ideal value (b=3.0), t-test was applied at a specified significant level (p<0.05) to test the null hypothesis Ho: b=3.0 against the alternate hypothesis Ha: b≠3. Therefore, data on LWRs for male, female and combined sexes of each mullet species were subjected to t-test by using modal 7 as suggested by Kumolu-Johnson and Ndimele [14] as follows;

(7)

Where t=t-statistics and S.E (b) is the standard error of regression coefficient ‘b’. The values of S.E (b) were obtained in the linear regression analysis by using Minitab demo 14.1 (Statistical software)

**Coefficient of correlation (r):**

The values of coefficient of correlation (r) were also calculated to measure the degree of linear relationship between all above mention parameters. The values of Pearson linear coefficient of correlation ‘r’ were also determined by using formula of Hossain [15] as follows;

(8)

Whereas x=X-X and y=Y-Y. X and Y are the mean values that used to predicted the values of X and Y variables. The values of X and Y were calculated by the following equations suggested by Niel [16] as follows;

(9)

Whereas ΣX is the sum of X- values (independent variable) and ‘n’ is the sum of data.

(10)

Whereas ΣY is the sum of Y-values (dependent variable)

**Condition factor (K)**

The condition factor (K) value was calculated with the help of following formula suggested by Offem et al. [17] as follows;

(11)

Where W is the total body weight and L is the total body length.

4.4 Relative condition factor (Kn)

The values of relative condition factor (Kn) were calculated from the following formula suggested by Le Cren [12] and Ranzani-Paiva et al. [18] as follows;

(12)

Where W_{t} is the observed body weight and We is the theoretically estimated weight. Both Wt and We were expressed in grams.

**Length-Weight relationship of mullets**

The results of the length-weight relationships (LWRs) for the four mullet species were calculated separately for male, female and combined sexes, as given in the **Table 1a**. Analysis of t-test showed a highly significant relationships (p<0.05) between length and weight for male, female and combined sexes of four selected mullet species (except female of *Liza melinoptera*) Hence, if the total length increases than whole body weight of fish will also be increased accordingly. However, it was much better to use the logarithmic transformation equations than the Pearson linear regression equation, as the variability in weight for the different lengths of fish did not always remain constant.

Species | Sex | N | Length range (cm.) | Mean± S.D | Weight range (g) | Mean ± S.D | t-test |
p-value | |||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|

Max. | Min. | Max. | Min. | a | b | r | |||||||

Liza melinoptera | Combined sexes | 69 | 18 | 14.5 | 16.48 ± 0.95 | 72 | 24 | 47.68a ± 12.22 | 69.3 | 7.09 | 0.551** | 5.4 | 0.0a |

Female | 33 | 18 | 14.5 | 16.84 ± 0.76 | 72 | 24 | 53.93 ± 11.35 | 6.6 | 2.81 | 0.188* | 1.07 | 0.30NS | |

Male | 36 | 18 | 14.5 | 16.15 ± 0.99 | 72 | 30 | 41.94 ± 10.07 | 69.9 | 6.92 | 0.68** | 5.41 | 0.0a | |

Liza macrolepis | Combined sexes | 62 | 29 | 12.5 | 17.49 ± 3.23 | 500 | 25 | 78.6 ± 83.8 | 308 | 22.1 | 0.854*** | 12.69 | 0.0a |

Female | 41 | 25.5 | 12.5 | 17.74 ± 3.32 | 400 | 25 | 83.0 ± 75.8 | 251 | 18.8 | 0.827*** | 9.17 | 0.0a | |

Male | 21 | 29 | 13 | 17.0 ± 3.07 | 500 | 28 | 70.2 ± 99.1 | 440 | 30 | 0.929*** | 10.93 | 0.0a | |

Valamugilspeigleri | Combined sexes | 79 | 19.4 | 13.1 | 15.83 ± 2.01 | 68 | 20 | 42.35 ± 14.60 | 69.4 | 7.06 | 0.973*** | 36.82 | 0.0a |

Female | 32 | 19.4 | 13.1 | 16.07 ± 2.17 | 68 | 20 | 45.12 ± 15.76 | 68.6 | 7.07 | 0.978*** | 25.5 | 0.0a | |

Male | 47 | 19 | 13.5 | 15.65 ± 1.89 | 68 | 26 | 40.46 ± 13.61 | 68.7 | 6.97 | 0.97*** | 26.87 | 0.0a | |

Mugilcephalus | Combined sexes | 36 | 37.8 | 20 | 26.38 ± 4.73 | 685 | 80 | 232.5 ± 185.3 | 727 | 36.4 | 0.928*** | 14.54 | 0.0a |

Female | 16 | 36.6 | 20 | 26.11 ± 5.22 | 645 | 80 | 221.12±183.5 | 646 | 33.2 | 0.944*** | 10.68 | 0.0a | |

Male | 20 | 37.8 | 21.7 | 26.61 ± 4.43 | 685 | 104 | 241.5± 191.03 | 817 | 39.8 | 0.923*** | 10.18 | 0.0a |

Length (L) in cm; Weight (W) in g; N=sample size; S.D=Standard deviation. *** shows the strong correlation (r>0.70); ** shows moderate correlation (r>0.60); * represent weak correlation (r>0.50) NS=not significant (when p>0.05) a: significant at 5% level (p<0.05)

**Table 1a: **Regression parameters of the length-weight relationship (W=a. Lb) of the four species of family Mugilidae.

The log transform data of length-weight relationship (LWRs) was analyzed by the cube law to check whether the growth was positive or negative allometric, as shown in **Table 1b**. In the present study, the exponent b-values were also found to be varied from an isometric value (b=3.0) In male, female and combined sexes of *L. melinoptera* and *V. speigleri,* the exponent b-values was less than 3.0, while in case of *M. cephalus* and *L. macrolepis*, the exponent b-values was greater than 3.0. In general, the b-values reported for the combined sexes of all four mullet species ranged from 2.65 for *V. speigleri *to 3.59 for *L. macrolepis*. However, all regression coefficients (b) calculated in the present study for the four mullet species were lies within the expected range (2.5-4.0), therefore, suggesting that the result of length-weight relationship of this study was valid. This departure of b-value from an ideal value (b=3.0) was subjected to the t-test analysis. The test results revealed that except the females of *L. melinoptera,* the b-values of male, female and sex combined of these four mullet species were significantly departed from an ideal value (b=3.0).

Species | Sex | N | Log a | Log b | S.E (b) | r | t-test when b=3 |
p-value | G.T |
---|---|---|---|---|---|---|---|---|---|

Liza melinoptera | Combined sexes | 69 | -1.64 | 2.72 | 0.43 | 0.615** | -0.65 | 0.0a | ¯ |

Female | 33 | -0.21 | 1.58 | 0.85 | 0.316* | -1.67 | 0.07NS | ¯ | |

Male | 36 | -1.46 | 2.54 | 0.44 | 0.703*** | -1.05 | 0.0a | ¯ | |

Liza macrolepis | Combined sexes | 62 | -2.66 | 3.59 | 0.12 | 0.97*** | 5.09 | 0.0a | s |

Female | 41 | -2.65 | 3.59 | 0.13 | 0.977*** | 4.69 | 0.0a | s | |

Male | 21 | -2.62 | 3.54 | 0.27 | 0.95*** | 2.03 | 0.0a | s | |

Valamugilspeigleri | Combined sexes | 79 | -1.56 | 2.65 | 0.08 | 0.968*** | -4.38 | 0.0a | ¯ |

Female | 32 | -1.59 | 2.68 | 0.13 | 0.968*** | -2.54 | 0.0a | ¯ | |

Male | 47 | -1.51 | 2.6 | 0.1 | 0.964*** | -4.05 | 0.0a | ¯ | |

Mugilcephalus | Combined sexes | 36 | -2.74 | 3.54 | 0.23 | 0.937*** | 2.38 | 0.0a | s |

Female | 16 | -2.56 | 3.41 | 0.21 | 0.975*** | 1.95 | 0.0a | s | |

Male | 20 | -2.94 | 3.68 | 0.41 | 0.903*** | 1.66 | 0.0a | s |

*** shows the strong correlation (r>0.70); ** shows moderate correlation (r>0.60); * represent weak correlation (r>0.50) NS=not significant (when p>0.05); a: significant at 5% level (p<0.05); s represent positive allometric pattern of growth; -hows negative allometric pattern of growth; GT=growth type

**Table 1b:** Regression parameters of the length-weight relationship (log W=log a+log b L) of the four species of family Mugilidae. Length (L) in cm; Weight (W) in g; N=sample size; S.D=Standard deviation.

Highly significant correlation coefficients values (r>0.90; p<0.05) were obtained for the male, female and combined sexes for the three mullet species such as* M. cephalus, V. speigleri *and *L. macrolepis,* indicating that both length and weight of each mullet species were highly correlated with each other. The r-values for male and sex combined of *L. melinoptera* were moderately strong (r>0.70; p<0.05), while weak or insignificant (r=0.32; p>0.05) for female, hence, indicating that both length and weight were weakly correlated with each other. The scattered plot diagrams were also drawn to show the parabolic relationship between length and weight indicating the applicability of general cube law to all these four mullet species, respectively.

**Condition factor (K)**

The condition factor was determined only for observed body weights (**Table 1c**). In general, the mean condition factor (K) ranging from 0.99 (females of *L. melinoptera*) and 1.23 (males of* L. macrolepis*), as shown in the **Table 1c**. Thus, in general, the values of condition factor (K) obtained in the present study revealed that four selected mullet species of this study were in good condition.

Species | Sex | N | Length range (L) in cm. | Weight (Wt) range in grams. | Condition factor (K) range | Mean K value | Relative condition factor (Kn) Range | Mean Kn value | ||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | |||||

Liza melinoptera | Combined sexes | 69 | 18 | 14.5 | 72 | 24 | 1.6 | 0.67 | 1.06 | 1.51 | 0.66 | 1 |

Female | 33 | 18 | 14.5 | 72 | 24 | 1.6 | 0.67 | 0.99 | 1.62 | 0.7 | 1 | |

Male | 36 | 18 | 14.5 | 72 | 30 | 1.6 | 0.79 | 1.13 | 1.36 | 0.51 | 1 | |

Liza macrolepis | Combined sexes | 62 | 29 | 12.5 | 500 | 25 | 2.53 | 0.92 | 1.2 | 21.77 | -2.89 | 1.18 |

Female | 41 | 25.5 | 12.5 | 400 | 25 | 2.05 | 0.92 | 1.14 | 30.9 | -0.56 | 2.85* | |

Male | 21 | 29 | 13 | 500 | 28 | 2.53 | 0.98 | 1.23* | 9.35 | -1.58 | 1.81 | |

Valamugilspeigleri | Combined sexes | 79 | 19.4 | 13.1 | 68 | 20 | 1.24 | 0.85 | 1.04 | 1.15 | 0.82 | 1 |

Female | 32 | 19.4 | 13.1 | 68 | 20 | 1.2 | 0.89 | 1.03 | 1.17 | 0.86 | 1 | |

Male | 47 | 19 | 13.5 | 68 | 26 | 1.24 | 0.85 | 1.05 | 1.12 | 0.79 | 1 | |

Mugilcephalus | Combined sexes | 36 | 37.8 | 20 | 685 | 80 | 1.73 | 0.48 | 1.08 | 2.24 | 0.36 | 1.09 |

Female | 16 | 36.6 | 20 | 645 | 80 | 1.73 | 0.48 | 1.11 | 2.24 | 0.35 | 1.08 | |

Male | 20 | 37.8 | 21.7 | 685 | 104 | 1.4 | 0.83 | 1.05 | 4.38 | 0.64 | 1.4 |

*shows the highest value

**Table 1c:** Condition factor (K) and Relative condition factor (Kn) values of the four species of family Mugilidae. Length (L) in centimeters; Weight (Wt) in grams; N=sample size.

**Relative condition factor (Kn)**

For each mullet species, Kn values were calculated separately for male, female and combined sexes (**Table 1c**) The main difference between condition (K) and relative condition factor (Kn) was that condition factor (K) was used to measure the deviation of an individual from a hypothetical fish, while the relative condition factor (Kn) was used to measure the deviation of an individual from an theoretically expected weight at a specific length, as described by Omogoriola et al. [19].

The result of the present study revealed that the mean Kn values obtained for four mullet species of this study were ranged from 1.00 (*V. speigleri* and *L. melinoptera*) to 2.85 (females of *L. macrolepis*), respectively. The mean Kn values obtained for four mullet species of this study were either equal to or greater than expected value (Kn=1.0), therefore, they were in good condition. Furthermore, as the mean Kn values calculated for the *L. macrolepis* and *M. cephalus* was found to be higher than *V. speigleri* and *L. melinoptera*, therefore, the former species were found in more better physical conditions than later ones.

Lagler [20] and Wootton [21] suggested that if fish grow isometrically than it retains its body shape and its specific gravity will also remain unchanged during the life time, therefore, in such cases, its b-value must be equal to 3.0. Hence, this growth pattern in fish will follow the cube law. But under natural condition, most fish do not show the cube law, because they change their body shape as they grow or increase in size and become heavier in one season and lighter in the other season. Hence, Le Cren [12] reported that the actual relationship between length and weight of fish may departure from the ideal value (3.0), which may be due to certain environmental conditions or condition of fish. Hence, the b-value for each fish species could be significantly greater or less than ideal value (3.0), indicating that growth pattern is allometric [22]. Thus, if b-value is equal to 3.0, than growth is isometric. But if b-value is less than 3.0, than fish becomes more slender as it increase in length, therefore, its growth will be negative allometric that might be because habitat conditions are not suitable for its growth. On the other hand, if b-value is greater than 3.0, than fish becomes heavier and showed positive allometric pattern of growth for their specific lengths, which may be due to optimum condition [23,24]. Hence, the high b-values (2.5-4.0) obtained in this study for the four mullet species revealed that the present condition of these mullet species exists in the study area was more suitable for feeding and optimum growth of fish (**Table 1b**).

The overall result of this study revealed that both *L. melinoptera* and *V. speigleri *showed negative allometric pattern of growth with the b-values less than ideal value (3.0) On the other hand, the b-values of *M. cephalus *and *L. macrolepis* were greater than the ideal value (3.0), therefore, indicating the positive allometric growth. While the results length-weight relationship of* L. melinoptera* showed differences in the b-values between male, female and combined sexes. The deviation of b-value from the ideal value (3.0) was found to be statistically highly significant (p<0.01) in all four mullet species (except the female of *L. melinoptera* that showed insignificant (p>0.05) departure from ideal value, that is 3.0) of this study. Hence, the b-values could be varied among the different populations of same species. These variations in the b-values for the same species might be due to the differences in sampling time, sample size, differences in ages and growth rates, maturity stages and food availability [25]. Hossain [15] also reported that the LWRs in fishes can also be affected by certain factors such as habitat, spawning season, condition environment (including temperature, salinity and seasonality), food availability, sex, maturity stages, appetite and gonadal content that can effect on the b-values, even within the same species. Therefore, in the present study, the variations observed in b-values among the four mullet species as well as within the same species might be because of the above mention reasons.

The results of LWRs of these four mullet species were compared with the available literature. The length-weight relationship for the *M. cephalus* of the present study revealed that the exponent b-value for combined sexes was significantly departed from the ideal value (b=3.0) This b-value was higher than those observed by Luther [5], Wijeyaratne and Costa [6] and Aleleye-Wokoma et al. [7] from the sea near Mandapam (India), Negombo lagoon (Sri Lanka) and Bonny estuary (Nigeria) The b exponent of *L. macrolepis* was greater than 3.0 in this study, which was higher than those observed by Luther [5] Wijeyaratne and Costa [6] and Chu et al. [26]. Hence, LWRs of *L. macrolepis* in the present study revealed the positive allometric pattern of growth, while Luther [5], Wijeyaratne and Costa [6] and Chu et al. [26] studies revealed isometric growth pattern. The calculated b-value of V. speigleri in the present study was significantly less than 3.0, which was in agreement with Karna et al. [9] who also reported similar value from Chilika lagoon of India.

The change in body weight in relation to the total length was not always based on specific gravity but due to change in the form of volume. According to the Le Cren [21] all these changes can be analyzed by the condition factor (K) or “Pondered index”. The condition of any fish species can be determined on the basis of its length-weight relationship (LWRs) data [17]. Therefore, Wotton [19] reported that if b value is equal to 3.0, than K value remain constant. However, if weight of fish will increases more rapidly than the cube of its length (b>3.0), than its K value will be increases with increasing the length of fish. While on the other hand, if weight of fish increases less than the cube of its length (b<3.0), its K value will tend to be decreased. With increase in the length of fish [27]. Hence, the value of condition factor (K) appears to be different with increase in the size or weight of fish.

Among the other mullet species, the highest K values recorded for the *L. macrolepis* was indicating that it can survive well even when environmental condition (both abiotic and biotic) were less favourable as reported by Akombo et al. [28] for other fish species. Except *M. cephalus*, males of *L. melinoptera *(1.13), *V. speigleri* (1.05) and *L. macrolepis* (1.23) showed the highest mean value of condition factor (K) than females, indicating that males of these mullet species at a given length were heavier than females of similar length. This might be due to the presence of testes that were heavier than ovaries in females. Therefore, the maximum K values may coincides with the beginning of spawning season [26], however, when fish reached at spent stage, than K values will decline or minimum due to the considerable reduction in gonadal weight of fish [6]. Offem et al. [26] observed that as the condition factor was seems to be totally depends on the length and weight of fish, therefore, all those factors that can effect on the lengthweight relationship of fish, could also produce variations in condition factor (K) In the present study, both length and weight of four mullet species of this study were highly correlated with each other. Therefore, K values of this family would tend to be increased with increase in length of fish, which was in agreement with Ali et al. [29]. However, decreasing trend in K values with increase in length of fish was observed in females of *L. melinoptera* of this study. According to the Lawson et al. [30], the low K value was considered as a period, when fat stored in fish body was utilized for spawning, while its high value was indicating a period of maximum feeding, followed by gradual accumulation of fat for the preparation of a new reproductive period. Hence, the variations in K values of four mullet species obtained in this study might be due to the differences in the maturation of gonads, increases or decrease in feeding behavior, amounts of fats or population changes that may occurs due to the changes in food items, as reported by Akombo et al. [25] for other fish species.

According to the Le Cren [12], the relative condition factor (Kn) was defined as ratio between observed and theoretically expected weight for a given length. Thus, the relative condition factor (Kn) allows the statistical comparison of estimated Kn value to the standard value or expected value, Kn=1.0 [31,32]. According to the Ranzani-Paiva et al. [33], if observed weight (Wt) of an individual is equal to theoretically expected weight (We) for a specific length, than its Kn value is equal to standard or central value (Kn=1.0) However, if observed or total weight of individual is less than the expected weight, the mean Kn value is less than one (Kn<1.0), indicating that such individual will be in poorer condition. While if observed weight of an individual is greater than the expected weight, than the mean Kn value of fish is greater than one (Kn>1.0), which revealed that such individual will be in good condition. Hence, Kn values obtained for any particular fish species can be used to compare with its with standard value (Kn=1.0), in order to determine the condition of fish species as observed by Le Cren [12], Lagler [34], Swingle [35] and Zubia and Rehana [36] for various fish species.

The overall results of this study revealed that the mean values of relative condition factor (Kn>1.0) for M. cephalus and L. macrolepis revealed that the total weight (Wt) in these two mullet species was found to be greater than the theoretically expected weight (We) While mean values of relative condition factor (Kn=1.0) of the remaining other two species such as, *V. speigleri* and* L. melinoptera* showed that they have a total weight (Wt) was very close to the theoretically expected weight (We), as shown in the **Table 1c**. Therefore, in the present study, both *M. cephalus* and *L. macrolepis* with highest Kn values were in more better condition than the other two mullet species i.e., *V. speigleri* and *L. melinoptera*, respectively. These fluctuations in Kn values might be due to the several reasons such as condition of environment, seasonality, abundance of food resources, maturity stages, size range, ages, sex, increases or decrease in feeding activities, amounts of accumulated fats and effect of parasites [13,37,38]. Information regarding to the relative condition factor (Kn) of these four mullet species on the Pakistan coast was still limited. However, Luther [5] had reported the Kn values for combined sexes of *L. macrolepis* ranged from 0.81 to 1.13, while in *M. cephalus,* Kn values ranged from 0.88 to 1.10, therefore, both were in good condition.

The study length-weight relationship (LWRs) data of four mullet species of this study of length could be consider as very useful tools in the fisheries research, because it permits the conversion of growthin- length equation to growth-in-weight that can be used in fisheries management, fish biology, physiology, ecology, heath, condition and growth pattern of fish [17,24,39]. The value of condition factor (K) of these mullet species revealed that the condition of Karachi coast was found to be more suitable for their growth. Anene [40] observed that as the condition factor was greatly influence by certain abiotic and biotic factors of the environments, hence, can be used to assess the state of an aquatic ecosystem of fish in which they lived. As the mean Kn values for all four mullet species were equal to or greater than the expected or standard value (K_{n}=1), therefore, these species were found to be in good condition during the period of study. Hence, the analysis of relative condition factor (K_{n}) could also be used to assess the condition of a fish [34].

- Nelson JS (2006) Fishes of the world. 4th ed., John Wiley & Sons, Inc., Hoboken, New Jersey, USA.
- Bianchi G (1985) FAO species identification sheets for fishery purposes. Field guide to the commercial marine and brackish water species of Pakistan. Prepared with the support of PAK/77/033 and FAO (FIRM) Regular Programme. Rome, FAO, 200.
- Fahmida I (2002) Mullets of Korangi Creek. Karachi Rec ZoolSurv Pakistan 14: 11-18.
- Luther G (1963) Some observations on the biology of Liza macrolepis (Smith) and Mugilcephalus Linnaeus (Mugilidae) with note on the fishery of grey mullets near Mandapam. Indian Journal of fisheries 3: 642-666.
- Wijeyaratne MJS, Costa HH (1987) The biology of grey mullets in a tropical lagoon in Sri Lanka. Mahasagar Bulletin of the National Institute of Oceanography 20: 163-170.
- Aleleye-Wokoma IP, Hart SA, Hart AL (2001) Age and growth of Mugilcephalus (Linnaeus, 1758) (Perciformes: Mugilidae) in Bonny Estuary. In: 14th Annual Conference of Fisheries Society of Nigeria, 19-23 January 1998 in Ibadan, Nigeria: 119-129.
- Chu WS, Hou YY, Ueng YT, Wang JP (2012) Length-weight relationship of large scale mullet, Liza macrolepis (Smith, 1846), of the southwestern coast of Taiwan. African Journal of Biotechnology 11: 1948-1952.
- Karna SK, Sudarsan P, Guru BC (2011) Length-Weight Relationship (LWR) and Seasonal distribution of ValamugilSpeigleri (Valancienues) through size-frequency variation and landing assessment in Chilika Lagoon, India. Asian J ExpBiolSci 2: 654-662.
- Abbas G (2000) Length weight relationship composition of raw fish consumed in Bahrain. Pakistan Journal of Biological sciences 11: 55-61.
- Harrison IJ, Senou H (1999) The living marine resources of the Western Central Pacific, Vol. 4. Bony fishes, Part 2, (Mugilidae-Carangidae), edited by Carpenter K, Niem VH, FAO, Rome, Italy.
- Le Cren ED (1951) The length-weight relationships and seasonal cycle in gonad weight and condition in the perch (Percafluviatilis) Journal of Animal Ecology 20: 201-219.
- Anibeze CIP (2000) Length weight relationship and relative condition of Heterobranchuslongifilis (Valenciennes) from Idodo River, Nigeria. Naga, The ICLARM Quarterly 23: 34-35.
- Kumolu Johnson CA, Ndimele PE (2010) Length-weight relationships and condition factors of twenty-one fish species in Ologe Lagoon, Lagos, Nigeria. Asian Journal of Agricultural Sciences 2: 174-179.
- Hossain MY (2010) Morphometric relationships of length-weight and length-length of four Cyprinid small indigenous fish species from the Padma River (NW Bangladesh) Turkish Journal of Fisheries and Aquatic Sciences 10: 131-134.
- Niel AW (1995) Introductory statistics. Addison-Wesley Publishing Company. Inc., New York. 4th edition 938.
- Offem, BO, Samsons YA, Omoniyi IT (2009) Length-weight relationship, condition factor and sex ratio of forty six important fishes in a tropical flood river. Research journal of fisheries and hydrobiology 4: 65-72.
- Ranzani-Paiva MJT, Silva-Souza AT, Pavanelli GC, Takemoto RM (2000) Hemitological characteristics and relative condition factor (Kn) associated with parasitism in Schizodon Borelli (Osteichthyes, Anostomidae) and Prochiloduslineatus (Osteichthyes, Prochilodontidae) from Parana River, Parana, Brazil. ActaScientiarum 22: 515-521
- Omogoriola HO, Willams AB, Adegbile OM, Olakolu FC, Ukaonu ST, et al. (2011) Length-weight relationship, condition factor (K) and relative condition factor (Kn) of Sparids, Dentexcongoensis (Maul, 1954) and Dentexangolensis (Maul and Poll, 1953), in Nigerian coastal water. Int J BiolChemSci 5: 739-747.
- Lagler KF (1952) Fresh water fishery biology. WC Brown Company, Dubuque, Iowa, 360
- Wootton RJ (1990) Ecology of teleost fishes. Chapman and Hall. Upper Saddle River, New Jersey, USA.
- Gayanilo FC, Pauly D (1997) FAO ICLARM stock assessment tools (FISA T): References manual, FAO Computerized information series: 262.
- Wootton RJ (1998) Ecology of teleost fishes. 2nd edition. Chapman and Hall. Upper Saddle River, New Jersey, USA.
- Abowei JFN (2010) The Condition Factor, Length–Weight Relationship and Abundance of Ilishaafricana (Block, 1795) from Nkoro River Niger Delta, Nigeria. Advance Journal of Food Science and Technology 2: 6-11.
- Weatherley AH, Gill HS (1987) The biology of fish growth. Academic Press, London, UK, 443.
- Chu WS, Hou YY, Ueng YT, Wang JP (2012) Length-weight relationship of large scale mullet, Liza macrolepis (Smith, 1846), of the southwestern coast of Taiwan. African Journal of Biotechnology 11: 1948-1952.
- Zubia M, Rehana YF (2011b) Frequency distribution pattern, length-weight relationship and condition factor of four species of family Gobiidae (order Perciformes) collected from Korangi fish harbor, Karachi, Pakistan. International journal of biology and biotechnology 8: 47-53.
- Akombo PM, Atile JI, Adikwu IA, Araoye PA (2011) Morphometric measurements and growth patterns of four species of the genus Synodontis (Cuvier, 1816) from Lower Benue River, Makurdi, Nigeria. International Journal of Fisheries and Aquaculture 3: 263-270.
- Ali M, Salam A, Anas M (2002) Weight-length relationship and relative condition of Oreochromismossambicus, an exotic fish species, in river Indus, Pakistan. Pakistan Journal of Zoology 34: 125-128.
- Lawson EO, Akintola SO, Olatunde OA (2010) Aspects of the Biology of Sickle fin mullet, Liza falcipinnis (Valenciennes, 1836) from Badagry creek, Lagos, Nigeria. Nature and Science 8: 168-182.
- Verani JR, Sato Y, Fenerich-Verani, N, Vieira LJS (1997) Avaliacao de femeas de species icticasaptasainducao reproductive: criterioembasado no fator de condicao relative. In: Seminario regional de ecologia, 8, Sao Carios. Anais. UFSCar, Sao Carios: 323-332.
- Romagosa E, Narahara MY, Borella MI, Fenerich-Verani, N (2001) Selecao de femeas de matrinxa, Bryconcephalus, induzidas a reproducao. B InstPesca 27: 139-147.
- Ranzani-Paiva, MJT, Rodrigues E, Viega ML, Eiras AC (2001) Association between the hematological characteristics and biology of the “dourado” SalminusmaxillosisValenciennes, 1840, from Mogi-Guacu River. ActaScientiarum, 23: 527-533.
- Lagler KF (1956) Freshwater fishery biology. 2nd edition. W. C. Brown Company, Dubuque, Iowa, 403pp.
- Swingle WE (1965) Length-weight relationships of Alabama fishes. Auburn Univ (Ala.) AgrExpSta Zoology-Entomology Department series Fisheries No: 3.
- Zubia M, Rehana YF (2010) Length-weight relationship and condition and relative condition parameters of Lutjanus species of the family Lutjanidae collected from Karachi fish harbor, Karachi, Pakistan. International journal of biology and biotechnology 7: 505-509.
- Ranzani-Paiva MJT, Siva-Souza AT (2004) Co-infection of gills by different parasite groups in the mullet, Mugilplatanus Gunther, 1880 (Osteichthyes: Mugilidae) effect on relative condition factor. Brazilian Journal of Biology 64: 677-682.
- Pervin MR, Mortuza MG (2008) Notes on length-weight relationship and condition factor of freshwater fish, Labeoboga (Hamilton) (Cypriniformes: Cyprinidae) Univ J ZoolRajshahiUniv 27: 97-98.
- Adeyemi SO (2010) Length – Weight, Length – Length Relationship and Condition Factor of Synodontisresupinatus At Idah Area of River Niger, Nigeria. 6: 85-90.
- Anene A (2005) Condition factors of four cichlid species of a man-made lake in Imo state, Southeast, Nigeria. Turk J Fish AquatSci 5: 43-47.