African Journal of Fisheries Science

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (7), pp. 267-272, October, 2017. © International Scholars Journals

Full Length Research Paper

Cultivation of black tiger shrimp Penaeus monodon (Fabricius 1798) at the nursery stage in biofloc technology (BFT) system

Vicente Mabote¹, Delfina Muiocha², Manecas Francisco Baloi^3*

¹AQUAPESCA Farm, Inhassunge, Mozambique.

²Instituto Nacional de Investigação Pesqueira, 389, PO Box 4603, Maputo, Mozambique.

³Escola Superior de Ciências Marinhas e Costeiras, Universidade Eduardo Mondlane, PO Box 128, Quelimane, Mozambique.

Corresponding author's E-mail: [email protected]. Tel. 00258 84 238 1935

Accepted 27 June, 2017

A 120-day experiment was conducted to evaluate the performance of Penaeus monodon postlarvae (PL) reared during the nursery phase in a BFT limited water exchange system. The PL25 (0.19 ± 0.01g) were divided into two treatments: clear water (CW) and Biofloc system (BFT) at a stock density of 200 PL m^-2. Three replications were applied in each treatment. The PLs were fed three times per day applying a 38% commercial crude protein diet. Significant differences (P < 0.05) were found between treatments in all water quality parameters except in terms of water temperature. The BFT treatment showed higher water quality parameters with the exception of dissolved oxygen. The mean final weight, growth rate and biomass in the BFT treatment was higher than the CW treatment (P < 0.05); however, survival did not differ between treatments (P < 0.05). FCR was lower (P < 0.05) in the BFT treatment than the CW treatment. Results indicate that a BFT system improved the growth performance of P. monodon and maintained the water quality within a range which is considered optimal for the species.

Keywords: BFT, Penaeus monodon, postlarvae, water quality, growth performance.

African Journal of Fisheries Science ISSN: 2375-0715 Vol. 5 (6), pp. 260-266, September, 2017. © International Scholars Journals

Full Length Research Paper

Isolation of Edwardsiella tarda-like species and its frequency of occurrence in freshwater fish harvested for human consumption from Lake Hawassa and crater lakes around Bishoftu, Ethiopia

Nuredin Nemo¹, Tesfaye Sisay² and Takele Abayneh³

¹Dodota Sire district Livestock and Fishery Resource Office, Arsi Zone, Oromia Region, Dhera, Ethiopia.

²Unit of Biotechnology, College of Computational and Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia.

³National Veterinary Institute, Bishoftu/Debre-zeit, Ethiopia.

Corresponding Author. E-mail:[email protected]; Tel: +251 911 407632

Accepted 01 August, 2017

Abstract

A study was conducted to isolate Edwardsiella tarda-like species from apparently healthy freshwater fish (African cat fish, Clarias gariepinus and Nile tilapia, Oreochromis niloticus) originating from Lake Hawassa and crater lakes around Bishoftu, Ethiopia and thereby determine its distribution. Standard bacteriological examination of tissue specimens (kidney, liver and intestine) aseptically collected from fish harvested for human consumption resulted in a total of 16 isolates (10 from intestine, 4 from liver and 2 from kidney) showing similar colony and biochemical characteristics to E.tarda and were presumptively identified as E.tarda-like species due to the difficulties in differentiating them from the phenotypically similar new taxa viz. E.piscicida and E.anguillarum.  There was significant variation (P<0.05) in the chance of isolating the bacterium among the organs examined with the organism being most frequently isolated from the intestine. Of a total of 210 fish included in the study, the bacterium was isolated from 16 (7.6%) of them with significant difference (P<0.05) observed in its occurrence with respect to origin of fish host. The isolation of E.tarda-like species from apparently healthy fish in the current study indicates potential sources of disease epidemics in fish as well as safety concerns on local fish products consumed raw or improperly cooked.

Key words: African Catfish, Nile tilapia, Edwardsiella tarda, Ethiopia.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (5), pp. 255-259, May, 2017. © International Scholars Journals

Full Length Research Paper

Studies in variation in length-weight relationship, condition of factor and size distribution of Orechromis niloticus and Syndontis schall obtained in the ecology lower River Benue at Makurdi Nigeria

Azua ET and Akaahan TJ

Department of Biological Sciences, Federal University of Agriculture, Makurdi P.M.B. 2373 Makurdi Benue state Nigeria.

*Corresponding author E-mail: [email protected]

Accepted 04 June, 2017

Abstract

The study was carried out to investigate the length, weight, condition of factor and the size distribution of two different species which were O.  niloticus and S. schall  from River Benue. The fish samples were obtained from Wadata fish market. The length-weight relationship was determined using Le standard method. Variation in standard length of S.schall range from 26.00 to 40.10cm, while standard length varied from14.00 to 21.01cm in O. niloticus. Similarly, total length ranged from 28.30 to 42.90cm in S. schall  and  bodyweight  varied from 248.40  to 432.20g. The total length in O.niloticus ranged from 16.01 to 23.01cm and the bodyweight ranged from 66.60 to 86.20g. However the weight of S.schall was higher than that of O.niloticus and perhaps this was due to the condition of  factor of the two different fish species and their feeding habits.

Keywords: Orechromis niloticus, syndontis schall, length- weight, condition of factor.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (4), pp. 249-254, April, 2017. © International Scholars Journals

Full Length Research Paper

Microphyto benthic composition of the fecal matter of a benthic gastropod Pachymelania aurita (O.F. Müller, 1774) in an estuarine ecosystem: Microphyto benthos as important food source for benthic invertebrates.

R.E Uwadiae

Benthic Ecology Unit, Department of Marine Sciences, University of Lagos, Akoka, Lagos, Nigeria. E-mail:[email protected]; [email protected]. Tel: +2347059497190.

Accepted 14 March, 2013

Abstract

The microphyto benthic assemblage in the fecal matter of a benthic gastropod Pachymelania aurita in a tropical estuarine lagoon was investigated by microscopic examination of the fecal matter. Two hundred and forty specimens comprising 120 juveniles and adults were used for this study. Comparison was made between microphyto benthos consumed by juveniles and adults. And to determine the actual source of the microphyto benthos recorded, comparison was also made between species recorded in the fecal matter of specimens direct from the wild and those exposed to sediment in the laboratory. The microphyto benthic organisms recorded consist of two major groups, blue-green algae (Anabaena, Aphanocapsa) and diatoms (Navicula, Synedra, Cyclotella, Nitzchia). Navicula and Cyclotella were the most important taxa in terms of abundance and frequency. There were no variations in the microphyto benthos consumed by the adults and juveniles. The assemblage observed in the fecal matter of specimens of P. aurita exposed to sediment in the laboratory represent a slightly different array of organisms with representation of Cyanobacteria which were absent in the fecal matter of specimens collected directly from the wild. The result of the study further buttresses the claim that benthic microalgae serve as major source of organic matter supporting benthic invertebrates.

Keywords: Microphyto benthos, fecal matter, food, benthic invertebrates.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (3), pp. 238-248, March, 2017. © International Scholars Journals

Full Length Research Paper

Effect of varying dietary proportions of linseed and olive oils on fatty acid composition of Nile tilapia and African catfish under aquaponics culture system

¹Omolo Kevin Mbogo*, ²Onyango Arnold, ^1,5Magoma Gabriel, ³Munguti Jonathan,⁴Ogila Kenneth and ⁶Masinde WP

¹Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology. P.O Box 62000-00200 Nairobi,

²Department of  Food Science and Technology, Jomo Kenyatta University of Agriculture and Technology P.O Box 62000-00200 Nairobi,

³Kenya Marine & Fisheries Research Institute, National Aquaculture Research, Development & Training Center, Sagana. Kenya.P.O Box 451-10230 Sagana,

⁴Department of Zoology, Jomo Kenyatta University of Agriculture and Technology,  P.O Box 62000-00200 Nairobi,

⁵Pan-African University, Institute for Basic Sciences , Technology and Innovation , P. O. Box 62000 00200 Nairobi,

⁶Department of Horticulture, Meru University of Science and Technology P.O Box 972-60200 Meru.

*Corresponding author E-mail: [email protected]

Accepted 03 February, 2017

Abstract

This study evaluated the effect of varying proportions of linseed and olive oils in fish diets on the fatty acid composition of tilapia and catfish liver and muscles under aquaponics culturing system after 150 days of feeding period. Experimental diets contained linseed, sunflower and olive oils at a varying composition of between 0 to 100% and commercial diet as a control feed (table 1). Gas chromatography was used to analyze fish tissue fatty acid profiles. Significantly high composition of n-3 fatty acids were observed in tilapia fed diet 1 (p<0.05) with DHA (C22.6) being the dominant n-3 fatty acids at 12.2% and 10.8% in tilapia muscles and liver respectively (table 4 and 5). In catfish, muscle and liver had 10.4% and 9.7% DHA content respectively (table 6 and 7). The muscle accumulation of n-3 fatty acid was significantly higher than liver in both fish species an efficiency in their retention and relative resistance of DHA to β-oxidation in the fish muscles. In both tilapia and catfish, the tissue n-3 fatty acids decreased with the reduction in linseed oil proportion in the diet feed suggesting direct influence of dietary oil composition on tissue fatty acid composition.

Keywords: Catfish, tilapia, DHA, EPA, n-3 fatty acids, linseed oil.

African Journal of Fisheries Science ISSN 2375-0715 Vol. 5 (3), pp. 229-237, March, 2017. © International Scholars Journals

Full Length Research Paper

A study of the histology of gill, liver and kidney of Nile tilapia exposed to various sub-lethal concentrations of aqueous extract

*¹Toyin Akinjide, ²Emmanuel Akanbi and ²Gbenga Davies

*¹Department of Fisheries, Faculty of Agriculture, University of Maiduguri, Maiduguri,  Borno State, Nigeria.

²Department of Fisheries and Wildlife Management, College of Agriculture, Osun State University, Ejigbo, Osun State, Nigeria.

*Corresponding author email:  [email protected]

Accepted 13 September, 2016

Abstract

This work determined the toxicity of Moringa oleifera seed powder to the most cultivable fish species in Africa, Tilapia, Oreochromis niloticus, Fingerlings. Moringa oleifera (Moringacaeae) seed powder is a good water purifier; it contains polyelectrolytes, which constitute active ingredients in water treatment The 96-h bioassay was conducted to determine the median lethal concentration (LC₅₀) for Nile Tilapia, Oreochromis niloticus, fingerlings to aqueous extract of drumstick, Moringa oleifera seed. The 24-h, 48-h, 72-h and 96-h of M. oleifera applied to O. niloticus fingerlings were 252, 251,242, and 242 mg/l respectively. Toxic reaction exhibited by fish includes erratic movement, air gulping, loss of reflex, discoloration, molting, loss of scale, and haemorrhage. Haematological examination shows an increase in number of blood cell counts (PCV (%), Hb(g/mm³) RBC(10⁶/mm³), MCHC(T/L^-), from 17.55±0.7, 5.7±0.3, 3.7±0.1, 1.1±0.1,31.2±1.7 in control to 23.0±4.2, 7.7±1.5, 3.9±0.1, 2.6±0.3, 34.1±1.4 in higher concentrations, while there was reduction in the number of ESR(%), MCH (pg), and MCV (µ³) from 12±1.4, 5.0±0.9 in control to 9±1.4, 3.4±0.9 in higher concentrations in fingerlings tilapia. The histological changes in the gill, skin, liver and kidney includes different level of degeneration of cells, lamellar hyperemia; hypertrophy of gill arch, Shrinkages and dermal erosion and necrosis of skin, while hyperplasia, disarrangement of hepatic cell, necrosis and vacuolation occurred in liver and kidney of fingerling Tilapia Oreochromis niloticus. Damages became severe with increasing concentration of M. oleifera to fish and time of exposure. There was no significant difference in water quality in the test, the result obtained before the test, during the test and after the test were found closed to the water quality parameters of the control. Results of the test provide baseline information and established safe limit of using aqueous extract of Moringa oleifera seed powder in fresh water pond. It was ascertained that aqueous extract of Moringa oleifera seed powder did not have adverse effects on water quality.

Key words: Toxicity, histological, aqueous extract, Moringa oleifera, tilapia, Oreochromis niloticus, fingerlings.