Introduction

Fish is a very important source of food for humans (FAO, 2010). Information about the food habits of fishes is on defin­ing predator-prey relationship (Saa et al., 1997) and the creation of trophic models as a tool to understanding completeecosystem (Lopez-Perata and Arcila, 2002; Bachok et al., 2004). It also guides the choice of feed stuff needed for ar­

tificial diet of cultured species for optimal production (Ketoye, 2007). Synodontis are generally bottom dwellers but severalspecies, including Synodontis membraneceus, spend most of their time swimming and feeding in an upside down position.They feed on worm, crustacean, detritus, seeds and decaying vegetable matter (Friel and Vigliotta, 2006), and are caught bymosttypes of fish gear.The serrated spines also cause them to become entangled in all types of nets. According to Ezenwa etal (1987),Synodontis species are commercially important fish species occurring inNigerian waters especially the Niger DeltaRegion.The different Synodontis species vary in commercial value in different locations; many are important food fishes andsomehave attractive skin colour and exhibit behavioral characteristics that make them potential ornamental candidates. Thespineof the males is much larger than those of the females (Friel and Vitgota, 2006) and they inhabit a large proportion of theAfricanfresh waters (Idodo Umeh, 2003).

S. membranaceus is highly relished as either fresh or smoked-dried fish. S membranaceus is generally preferred byfishermenand consumers because of its relatively large sizes which command a higher market value than other species of thegenus (Owalabi, 2005). Olojo and Olum (2003) observed monthly variations in feeding intensity which was determined asa measureof the percentage of food containing stomachs. S membranaceus is regarded as omnivorous, feeding on insects,nematodes,crusteaceans, mollusks, annelids, seeds, algae, fish scales, detritus, insect larvae and worms (Fagade, 1983;Win­emiller,1996and Idodo-Umeh, 2003). Agood knowledge offood and feeding habits offish species is very vital in fish culture(Njoku,et al. 2009) with regard to evolution (Collar, et al. 2009), selection of prey, predation etc (Allison and Sikoki, 2013)

Materials And MethodThis studywas carried out using a total of 95 fresh specimens of S membranaceus that were bought from fishers of OgobiriRiver,which is a fresh water ecosystem, in Southern [jaw Local Government Area of Bayelsa State. The study lasted fromApril- June, 2012 of which 44 specimens were males and 51 were females. The total length (ern) and weight (kg) were,

AbstractThefood andfeeding habits of Synodontis membraneceus of Ogobiri River of Bayelsa State, Nigeria was studied using 44 male and 51female specimens that were boughtfrom fishers in the study area measuring between 5 and 25 em total length. The Numerical and theFrequency of Occurrence method of analysis were used. For the males, thefood items by the numerical method were copepods (168),insects, (118), Cladocera (69), and unidentified items (32). In thefemale specimens, thefood items were Cladocera (286), Insect (216)Copepod (100) and unidentified organisms/materials (65). In the Frequency of Occurrence method for the males, Copepod was stillthe highest with a total of (48), Cladocera (44), Insects (29) and unidentified (I 6). For thefemales, Cladoera (48), Insects were (30)followed by Copepods (35) and unidentified (J9). The Percentage composition of food items by the Numerical method was Cladocera(45.5%), Insects (34.5%), Copepod (12.5%), and unidentified items (7.0%) while the Percentage Frequency of Occurrence was, Cla­docera (30.5%), Insects (30.9%), Copepod (29.6%), and unidentified items (9.0%).Keywords:Numerical method,frequency of occurrence, S. membraneceus, Ogobiri River.

Allison, M. E. / Youdubagha, S. E.

Preliminary studies on the food and feeding habits of Synodontismembraneceus from Ogobiri River, Nigeria

233

r

234

Cladocera Insects Copepod UnidentifiedSize Range Number items

of fish F % F % F % F %5·10 cm 15 11 23 8 23 7 23.3 3 1611·15 cm 12 13 27 11 31 8 26.7 6 3216·20 cm 19 20 42 12 34 13 43.3 9 4721-25 cm 5 4 8 4 11 2 6.7 1Total 51 48 100 35 100 30 100 19 100

In the frequency of occurrence method for the females (Table 2b), Cladocera was the highest (48), followed by Insect(35), Copepods (30) and unidentified organisms/materials (19).

Table 2b: Frequency (F) of occurrence and % of food items in female S. membranceceus in Ogobiri River.

Number Copedpod Cladocera Insects UnidentifiedSize Range of fish items

F % F % F % F %5-10cm 8 11 23 10 23 4 14 1 611·15cm 16 15 31 15 34 11 38 6 3816-20cm 12 11 23 13 29 9 31 5 3121·25cm 8 11 23 6 14 5 17 4 25Total 44 48 100 44 100 29 100 16 100

Table 2a: Frequency of Occurrence (F) and % of food items in male S.membranaceus in Ogobiri River.

In the frequency of occurrence method for the males (Table 2a), Copepod W3S still the highest with a total of (48), fol­lowed by Cladocera (44), Insects (29) and unidentified (16).

Number of Cladocera Insects Copedpod IUnidentified itemsSize Range fish No. % No. % No % No. %5-10cm 15 94 33 62 29 30 30 13 2011-15cm 12 88 31 68 31 35 35 15 2316-20cm 19 93 32 75 35 25 25 21 3221·25cm 5 11 4 11 5 10 10 16 25Total 51 286 100 216 100 100 100 65 100

Table lb: Numerical analysis and % of food items in female S.membranaceus in Ogobiri River.

A total of 5l female specimens were studied out of the 95 specimens, By the Numerical method of analysis, the fooditems were Cladocera (286), Insect (216), Copepod (100) and unidentified (65) (Table lb).

I

Number Copepod Insects Cladocera Unidentified itemsSize Range of fish No % No % No % No %5-10cm 8 '40 24 11 9 16 23 4 1311-15cm 16 33 20 37 31 17 25 9 2916-20cm 12 50 30 49 42 26 38 11 3421-25cm 8 45 26 21 18 10 14 8 25Total 44 168 100 118 100 69 100 32 100

Table 1a: Numerical analysis and % of food items in male S.membranceceusin Ogobiri River

By the numerical method of analysis the food items of the 44 male specimens of S. membranaceus were Copepod (168) fol­lowed by Insects, (118), Cladocera (69), and unidentified items (32) as shown in Table lao

measured for each specimen. The gut of the fish was removed by making a longitudinal incision along the mid ventral linefrom the mouth to the anus to expose the visceral organs. The stomachs were cut open and the content examined with stereomicroscope to determine the food of the fish which was analyzed by the numerical and frequency of occurrence methods(Hyslop, 1980). In the numerical method the number of different food items were counted and recorded. In the frequency of

V1 occurrence method, all stomachs containing particular food items were recorded

P1{UCEEVINGS OF 2t\TH ANNUAL CONFERENCE, NOV. 25-30, 2013

235

ConclusionThe results of the present study indicated S membranaceus as an omnivorous species feeding on any available food item inits environment such as cladoceras, copepods and insects and this makes it suitable for culture in fresh water ponds.

REFERENCESAllison, M.E. and Sikoki, F.D. (2013). Food and Feeding Habits of Parailiapellucid(Boulenger, 1901) (Schilbeidae) in the Freshwater

Reaches of the Nun River of the Niger Delta, Nigeria. Int 'IJ.of Adv Fish. and Aquatic Sci Vol. 1 (I): 1-14

Aoyiola and Fatureti (1990). The food and feeding habits of mud catfish, Clarias gariepinus caught from the wild. J. WestAfricanFisheries 5: 249-255.

Bachok, Z., Mansor, M. I.,Noordin, R. M. (2004). Diet composition and food Habits of Demersal and Pelagic Marine Fishes fromTerengganu Water, East Coast of Peninsular, Malaysia, NAGA, Vol. 27: 3-4.

Collar, D.C., O'Meara, B.C., Wainwright, P.C., and Near, T.J. (2009). Piscivory limits diversification of feeding morphology inCentrarchid fishes. Evolution 63: 1557-1573.

Ezenwa, B., Alegbeyele, 0., Njwumba, A and Antanwu, (1987). Nigeria Waters, A Research Survey (1978-1985) 136.Proceedings,FISON. Port Harcourt Rivers State.

Fagade, S. O. (1983). The Biology of Chrornidotilapia guntheri from a small Lake, Arch Hydrobiol. 97:60-70.

DiscussionThe study revealed that Synodontis membranaceus does not have a strict feeding habit being an omnivore and a predator. Thestomach contents of S membranaceus of this study are to some extent in' agreement with King (1995) for Simembranaceusin River Nile and Owolabi (2005) in Jebba Lake, Nigeria. Other observations with slight variations include Petr (1967) on Smembranaceusof Lake Volta, Willoughby (J 974), in Lake Kainji and in lower River Benue. These variation in the stomachcontent of S membranaceus from different fresh water bodies, confirm the fact that the fish does not have a strict feedinghabit. According to Olatunde (1987), the food item selected at any time of the year, depends on abundance and availabilityto the predator. It thus feeds on any material either of the plant origin or of the animal origin that is available in the habitat inwhich it lives.

The high insect and Cladocera occurrence in the stomach of Smembranaceus (30.9%) and (30.5%) respectively inthis study show that the fish prefer these food organisms in its habitat. The juveniles showed more inclination towards insectparticularly insect larvae than the adults which indicates that the food preference of S membranaceus changes with age likeClariasgariepinus (Ayinla and Faturoti, 1990) and Brienomyrus longianalis (Ikomi, 1996). The results of this study alsoindicated that S. membranaceus feeds more on animal materials than plant materials similar to the feeding habit of S Schall(Olatunde, 1987).

Table3: Percentage composition of the various food items of S.membranaceus by the numerical and frequency ofoccurrence of food items.

Foodspecies Number(%) Frequencyofoccurrence(%)CLADOCERAMoinasp 98 12.3 13 5.8Bosminasp 92 11.6 11 4.9Daphniasp 88 11.0 22 9.9Diaphanosoma 84 10.6 22 9.9

45.5 30.5INSECTChirinomusLarva 90 11.3 24 10.8ChirinomusPupa 87 11.0 25 11.2WaterBeetles 97 12.2 20 9.0

34.5 30.9COPEPODCyclopsSp 58 7.3 37 16.6Diopomus 41 5.2 29 13.0

12.5 29.6UnidentifiedOrganisms 60 7.5 20 9.0

TOTAL 795 100 223 100

The percentage numerical and percentage frequency of occurrence of food items in the stomachs of Smembraneceusexamined are shown in Table 3. By the numerical composition, Cladocera consisting of Moina, Bosmina, Daphnia and Di­aphanosomaspecies were predominant (45.5%) followed by Insects (Chironomus larva, pupa and Water Beetles) of 34.5%and Copepoda consisting Cyclop sp. and Diopomus (12.5%) while unidentifiable organisms / materials, constituted 7.5% ofthe number of food items in the stomachs examined. For the Percentage Frequency of Occurrence of food items, Cladocera Vl

(30.5%) and Insect (30.9%) were the dominant food items in the stomachs of Smembraneceus while Copepods and unidenti­'Tj

fied organisms constituted 29.6% and 9.0% respectively.

PROCEEDINGS OF 28TH FISON ANNUAL CONFERENCE, NOV. 25-30, 2013

FAO (2010). The State of World Fisheries and Aquaculture. Rome.

Friel, J. P. and Vigliotta, T. R. (2006): Synodontis acthoperca a new species from ogoove river system. Zootaxa 1125: 45-56.

Hyslop, E. J. (1980): Stomach content analysis: A review of methods and their application. J. Fish Biol. 17(4): 41 1-429

Idodo-Urneh, O. (2003): Freshwater Fishes of Nigeria: Taxonomy, Ecological Notes, Diet And Utilization.ldodo-Umeh Ltd ..

Kateyo, E. M. (2007). Ecology of a nutrient deficient inter surface zone of Lake Nabugabo, Uganda. Afr. J. Ecol., 45 (3): 282-284

King, M. (1995), Fisheries Biology, Assessment and Management: Fishing New Books Cambridge: Blackwell Sciences Ltd ..

Lopez-Peralta, R.H and Arcila C.A. (2002): Diet composition of fish species from southern Continental shelf of Colombia. NA GA WorldFish Cent. Quarterly. 25: 23-29.

Njoku, D.C., Keke, I.R. and Allison, M.E (2009): Food and Feeding Habits of Distichodus engycephalus of Lake Oguta: Search for aSustainable Aquaculture in the New Millennium. The Zool. Vol. 7: 122-129.

Olatunde, A. A. (1987). Some aspects of the biology of Synodontis schall in Zaria. Nig. J. Aquatic Sci. 4: 49-54.

Olojo, E. A. A. and Olurn K. B. (2003): Food and feeding habits of Synodnotis nigrita from Osun River, southwest Nigeria, NAGA Wildfish Center Quarterly, 26 (4): 21-24.

Owolabi, O. D. (2005): Some aspects of the biology of Synodontis membranaceus in Jebba Lake Nigeria. PhD Thesis, University ofIIorin, Nigeria.

Petr, T. (1967). Food preferences of commercial fishes in Volta Lake. Tech Report X Volta Basin Research Project. University of Ghana.

Sa-a, P., Palomares, M.L. and D. Pauly. (1997): The food items Table. In Fish Base 1997 CD-ROM, ICLARM, Manila, Philippines.

Winemiller, K. U. and Kelso-Winemiller, L. C. (1996). Comparative Ecology of the African Pike Hepsetus.

Willoughby, N.G. 1974. The ecology of the genus Synodontis in lake Kainji, Nigeria. PhD Thesis, University of Southampton.

PROCEEDINGS OF 28TH ANNUAL CONFERENCE, NOV. 25-30, 2013