Food and feeding habit of etroplus suretencis.harshath dg

fFood And Feeding Habit
Of Etroplus suratensis.
Harshath D G
Jr MFSc
MFK1814
Dept of FRM
College of Fisheries
Mangaluru

Outline
• Introduction
• Objectiaves
• Paper presentation
• Results and discussion
• Conclusion
• Refernces

Kingdom: Animalia
Phylum : Chordata
Class: Actinopterygii
Order: Perciformes
Family : Cichlidae
Scientific Name:Etroplus suratensis (Bloch, 1790)
Taxonomy
INTRODUCTION

Habitat and Ecology:
 Etroplus suratensis is a euryhaline species that inhabits mainly
brackish water and river mouths.
 It is an oval-shaped cichlid.
 dark spot at base of the pectoral fin.
 Most scales on the sides are with a pearly spot (Costa 2007).
 Adults engage in altruistic multiple parental care where several adults
care for a single brood that presumably were spawned by only two of
the adults.

Assessment Information
Red List Category & Criteria: Least Concern.
Justification: Etroplus suratensis is assessed as Least Concern in view of its wide
distribution, presumed large overall population, even though it has a relatively
declining trend in the wild, in Kerala.
Countries occurrence:
Native: India (Andhra Pradesh, Goa, Kerala, Orissa, Tamil Nadu, West Bengal);
Sri Lanka.

Range Description:
• Etroplus suratensis is distributed in the coastal regions of peninsular India and Sri Lanka.
• In India, the wild populations have been recorded from the states of Kerala and Tamil Nadu.
There are also populations in Goa, Andhra Pradesh, Orissa and West Bengal (Jayaram 1981 &
2010, Biju 2005). These are likely introduced populations (V.S. Basheer pers. comm.). The
species has now been introduced to dam reservoirs in the mountains and lakes and culture
ponds (Rema Devi et al. 2005).
Population: It is a common, but declining species.
Current Population Trend: Decreasing
Use and Trade: Etroplus suratensis is a popular foodfish. It is known locally as Karimeen and is
considered a delicacy. The species has been introduced to various other man-made habitats like tanks,
ponds and dam reservoirs for culture and export.

Why Feeding Habit Study?
 The study of food and feeding habits of fish forms an important part of fishery
research.
 It will throw light on the relationship between the fish and the food organisms.
 There is a direct correlation exists between the availability of fish and the abundance
of various food items on which they feed.
 The study of food and feeding habits of fish, it is an essential prerequisite for the
success of piscicultural practices which has great possibilities in a developing country
like India.

Introduction:
 Knowledge on the food and feeding is helpful for successful culture of fish in extensive and
intensive systems.
 The food and feeding habits of the pearlspot, Etroplus suratensis in different habitats have
been studied by several authors (Jhingran and Natarajan, 1969; Devaraj et al., 1975; De Silva et
al., 1984; Jayaprakas and Padmanabhan, 1985; Keshava et al., 1988; Keenleyside, 1991).
 The present study focuses on the food preference of E. suratensis in Vembanad wetlands.

Material and methods:
 Samples of E. suratensis were collected at fortnightly intervals from the landings of gillnet and
scareline fishing, along the Vembanad lake during October 2001-Dec 2003.
 The catch and effort of these two fishing methods were recorded.
 A total of 595 guts (length range of fish: 13 to 33.5 cm) were examined following the procedures
suggested by Windell and Bowen (1978). The guts along with contents were removed and
preserved in 5% formalin.
 The total length and fullness of the guts were recorded.
 The gut was exposed and the stomach contents were analysed using the frequency of occurrence
and point methods.
 For the frequency of occurrence, the number of stomachs containing food was quantified and
expressed as a percentage of allnon-empty stomachs.

The intensity of feeding was assessed based on the state of fullness
of the gut and the amount of food contained in it, and categorized as
• stage 1
Empty
• stage 2
Poor
moderate
• half-full gut stage 3
Moderate
• full stage 4
Full
• dilated gut stage 5
Gorged
The contents were isolated and
identified as far as
possible up to genus or family
level.
The stomach contents of each fish were
sorted into major groups such as
Filamentous algae
Detritus
Macro vegetation etc

Results and Discussion
 The fishery of E. suratensis in Vembanad Lake extends almost for the whole year supported
predominantly by two types of fishing practices viz., gillnetting in night hours and scareline
fishing during day time.
 The mean value of the catch per unit effort in gillnet fishery was 2.6 kg whereas in scareline
fishing it was 16.1 kg.
 The guts of 45% of such fishes were found to be in full and gorged condition.
 A comparison of the catch per unit effort indicates that the contribution of E. suratensis in day
catches is significant as compared to night catches in Vembanad Lake.
Observed thazat E. suratensis is a visual feeder and hence, higher catches are
possible during daytime.
De Silva et al. (1984)

Haroon (1998)
 Observed intense feeding activity by Oreochromis sp. during sunlight hours as
compared to night hours.
 (1981) reported that brooding individual is mostly non-foraging.
Ward and Samarakoon
 In the present study, an analysis of the fullness of the guts showed that all fishes
caught in scarelining were not brooders.

Food composition.
 Filamentous algae which formed the
primary food of E. suratensis, were
represented by Spirogyra and Oscillatoria
followed by Lyngbia and Fragillaria.
 Diatoms were represented mostly by
Pleurosigma, Nitzschia and Navicula
 Detritus and digested materials were
present as a major food constituent
throughout the year.

According to Hora and Pillai (1962)
The pearlspot favours bluegreen algae as food.
Ward and Samarakoon (1981) reported
that E. suratensis is a complete herbivore.
De Silva et al. (1984) observed
It as a predominant macrophyte feeder and not a complete herbivor
Detritus play a significant role in the diet of fishes in freshwater
systems (Bowen, 1981)

Seasonal variation:
The seasonal change in the abundance of food items of
E. suratensis is a reflection of the availability of food in the
environment.

A sizeable reduction in the population of diatoms and algae during monsoon months is a characteristic
phenomenon in Vembanad backwaters (Kurup, 1993).
The feeding intensity and diet composition of fish are apparently linked to the availability of food in
the habitat.
During premonsoon months (January- May), filamentous algae dominated the food items.
During postmonsoon months (August – December) detritus comprising of decayed vegetable matter
formed the major food item.

Feeding intensity and Gastrosomatic Index:
Percentage of empty stomach indicated lowest food intake during monsoon months
(June-July) coinciding with the breeding season (Jayaprakas and Nair, 1981) and
intense feeding during premonsoon months.
Gastrosomatic Index (Ga.S.I) varied between 3.95 and 5.70 among males and 3.40
and 6.31 among females, but the difference between months was not significant.

Relative Length of Gut:
The Relative Length of Gut (RLG) in E. suratensis was found to vary between 1.12 and 6.81
with a mean of 4.3.
The extremely long and coiled gut of E. suratensis indicates its adaptation for better digestion and
absorption of the plant and phytoplanktonic matter (Desai, 2003; Serajuddin and Rustam Ali, 2005).
Dasgupta (2004) observed that the RLG value increased with the increase of vegetable
matter as food and decreased with the increase of animal matter.
The selectivity and preference of different food items in different habitats establishes the
flexibility of the species to adjust to diverse environmental conditions.

omnivorous fishes varies between 0.7 and 4 times the length of the animal (Al-
Hussaini, 1949).
The ratio of intestinal length to the total length in E. suratensis ranges from 1.02
to 4.95 in euryhaline waters and from 2.45 to 5.54 in freshwater reservoirs and
these differences demonstrate the adaptability of the fish to different food.
The selectivity and preference of different food items in different habitats establishes the
flexibility of the species to adjust to diverse environmental conditions.

conclusion
 The fish is omnivorous, feeding predominantly on filamentous algae.
 Filamentous algae which formed the primary food of E.suratensis.
 E. suratensis is predominantly an algal grazer subsisting mostly on
filamentous algae and occasionally on small amount of unicellular algae.
 The extremely long and coiled gut of E. suratensis indicates its adaptation for better
digestion and absorption of the plant and phytoplanktonic matter.
 Dasgupta (2004) observed that the RLG value increased with the increase of vegetable
matter as food and decreased with the increase of animal matter.

Introduction:
• The pearl-spots (Family Cichlidae) form an important group among the brackishwater fishes
of the tropics.
• The three species found in India are Etroplus suratensis (Bloch), E. maculatus (Bloch) and E.
canarensis.
• Of these, the first two are commercially important and contribute to sizeable market
landings from the brackishwaters of the south-west coast of India.
• Inspite of their economic importance, the feeding ecology of these fishes is poorly known.
• The present paper deals with the results of a study on the food and feeding of Etroplus
suratensis in habiting the Rajakkamangalam estuary.
• Etroplus suratensis (Bloch) commonly known as “Karimeen” in Kerala.

Material and Methods
 Fish samples (sample size ca. 30) were collected from the landing centres around the Rajakkamangalam
estuary the period of March 2010 to Dec 2010.
 The guts, along with their contents were removed andpreserved in 5-8% formalin and subsequently
analysed both quantitatively and qualitatively.
 Food items were identified mostly upto the generic level as most of the items were in advanced stages of
digestion which rendered specific identification impossible.
 Quantitative analysis was carried out by using both occurrence and points volumetric methods
 Food composition in relation to size of fish was studied by examining the percentage occurrence of each
food item against size of fish. A total of 1241 specimens of size range 5.20 to 23.30 cm TL were examined
for the study of feeding ecology.

Results and Discussion
Results of qualitative analysis indicated dominance of filamentous algae and decayed
organic matter in the food content.
The proportions of major food items were:
• 29.15%
filamentous algae
•38.61%
decayed organic
matter
• 9.34%
miscellaneous items
• 2.66%
crustaceans
• 16.35%
semidigested matter
• 3.89%
sand and mud
 Decayed organic matter were recorded in all
months except December with peaks in July
(70.10%), May(53.75%) and June (53.21%). The
least was in November (10.72%).
 Filamentous algae (29.15%) fonned the second
major item of food. Maximum quantities were in
November (75.1%) and September (5.09%) and
the least in July (6.15%) and June (3.21%).
 Spirogyra formed the chief item among
filamentous algae.

List of food items of E. suratensis with their percentage
composition.

The food composition in relation to size of fish.
 Decayed organic matter was the most dominant item in fishes belonging to all the size
groups.
 The highest percentage was (80%) in size group 4.0-5.9 cm T.L. and the lowest (31.44%) in
size group 8.0-9.9 cm.
 Filamentous algae formed the second important food item and were recorded in all size
groups except 4.0-5.9 cm group.
 Their percentage ranged from 8.33% in 6.0 to 7.9 cm size group to 32.92% in the 8.0-9.9
cm size group.
 Crustaceans were found in all the size groups except 4.0-5.9 cm size groups, with the highest
quantity (10.91%) in 20-21.9 cm size group and the lowest (0.91%) in 10-11.9 cm size group.

Feeding intensity
 Higher feeding intensity was noticed during July followed by March, while poor
feeding was obvious in September and November.
 A decline in feeding activity was noticed during March-June.
 In the present investigation, percentage of empty stomach indicated lowest food
intake during (April) coinciding with the breeding season .
 High feeding intensity was noticed during July, March and April while
during the rest of the period feeding intensity was low.These variations were
probably related to the intensive feeding by spent .Fishes as well as those in
early stages of maturity.

conclusion
 The fish is omnivorous, feeding predominantly on filamentous algae.
 Filamentous algae which formed the primary food of E.suratensis.
Feeding intensity, related to maturation of gonads and spawning
activity, besides food availability.
This observation concluded that The different food groups varied monthly in their abundance
in the gut contents of the fish where it showed some seasonal preference to certain food
groups.

References.
Alikunhi K. H. (1957). Fish culture in India. Fann Bull. Indian Coun. Agne. Res. 20: 144.
Bhatnagar, G. K and K. Karamchandani (1970). Food and
feeding habits of Labeo fimbriata (Bloch) in river
Narmada near Hoshangabad (M.P). J. Inland Fish. Soc. India, 2: 30-50.
Bhuiyan, A. S and M. N. Islam (1988). Seasonal variation in
the percentage composition of the food of Xenentodon
cancila (Ham.) Uni J Zool Rajshahi Univ. 7: 33-36.
Bhuiyan, A. S., M. N. Islam, and N. Sultana (1992). Food
and feeding habit of Aspidoparia morar (Ham.) from the
river Padma. Uni J Zool Rajshahi Univ.10 & 11, 71-76.
Devaraj, K. V., B. Shantharam, and H.P.C. Shetty (1975). A comparative study of the food of juveniles
of the pearlspot Etroplus suratensis (Bloch) collected from estuarine
and freshwaters. Mysore J. Agric Sci. 9: 479-48J.
Hynes H. B. M. (1950). The food of freshwater sticklebacks
Gasterosteus acu/eatus and Pygosteus punjiCius with a
review of methods used in studies of food of fishes. J.
Anim. Ecol. 19 (I): 35-38

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