International Journal of Aquaculture, 2015, Vol.5, No.6 1
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capable of living in extreme conditions of
environment and it feeds on all available food
including diatoms, micro algae, filamentous algae,
bacteria, protozoa etc. associated with sand and
mud (Odum, 1970; Brusle, 1981; John, 1995;
Harridon and Senon, 1997). The fluctuation of RLG
values between 2.1 and 3.35 place
M.cephalus
of
Kayamkulam estuary in the category of omnivorous
fishes with adequate assimilation efficiency of
diatomous diet.
Table 1 Range and Mean values of length, weight, gut length and RLG in different size categories of
Mugil cephalus
Category
(mm)
No. of
fishes
examined
Length (mm)
Weight (g)
Gut length (mm)
RLG
Range
Mean
Range
Mean
Range
Mean
Range
Mean
110-120
20
110-115 111.5±0.99 15.14-28.3 19.15±1.68 319-376 331.6±9.45 2.77-3.26 2.97±0.77
120-130
18
120-129 123.91±2.05 21.48-28
25.21±1.27 315-346 325.55±4.21 2.46-2.88 2.63±0.23
130-140
22
130-139 134.86±0.80 24-35.2
27.47±1.84 322-373 341.43±7.16 2.31-2.76 2.52±0.34
140-150
29
140-149 144.7±1.00 28-45
29.4±2.42 315-456 396.4±12.32 2.15-3.18 2.78±0.32
150-160
14
150-157 152.45±1.23 34-59
49.32±1.70 343-511 403.64±13.82 2.22-3.35 2.93±0.41
160-170
12
160-168 164.5±1.21 43-64.5
56.36±2.05 367-411 394.82±4.10 2.18-2.56 2.42±0.11
170-180
17
170-178 174.55±0.87 57.86-71
62.85±2.42 380-421 394.36±5.32 2.16-2.47 2.32±0.13
180-190
10
180-188 184.1±1.55 60.15-104.5 68.43±14.32 412-535 420.16±3.42 2.23-2.84 2.42±0.27
190-200
12
190-195 193.5±0.78 69.1-85
72.18±6.93 416-445 428.87±8.40 2.13-2.34 2.28±0.18
200-210
6
200-202 200.8±0.80 100-102
101.4±0.80 421-440 428.5±6.44 2.1-2.21
2.17±0.12
No regular pattern was observed in the intensity of
feeding (Table 2.). Of all the specimen collected there
was a predominance (>50%) of poorly fed fishes
(empty and ¼ full stomachs) in all months and more
than 50% were in poor feeding stage. There is an
increase in the proportion of actively fed fishes from
September with its maximum during October (Figure
1). Monsoon season is characterized by the maximum
number of poorly fed fishes (74.63%) while the
maximum of actively fed fishes (28.21%) were during
Figure 1 Monthly fluctuations in feeding intensity (%) of
Mugil
cephalus
of Kayamkulam estuary
Table 2 The percentage of feeding intensities of
Mugil cephalus
during different months
Stomachs
May June July Aug Sept Oct Nov Dec
No. Examined 20 20
20 20 20 20 20 20
Empty
0
21.44 33.4 5
0
0
5
0
Trace
30 28.57 22.2 30 25 44.5 35 50
¼ full
40 28.57 22.2 55 30 22.3 15 0
½ full
10 14.28 11.1 5
15 0
20 20
¾ full
15 7.14 11.1 5
10 11.1 10 20
Full
5
0
0
0
20 22.3 15 10
the post monsoon period. It is probable that during
rainy season bottom flora in the environment is
greatly disturbed by the floodwaters and their growth
is hampered, thus reducing the overall availability of
the food items and reduction in the quantity of food
consumed by fish (Sarojini, 1951; De Silva and
Wijeyaratne, 1977; Kalita and Jayabalan,2000;
Al-Marzouqi,2012). While the intensive feeding
during the post monsoon period is due to the
availability of large quantities of algae and diatoms.
The various categories of food found in the stomach
and intestine of
M.cephalus
indicates the feeding habit
of the species on all available food. The gut contents
