African Journal of Fisheries Science

African Journal of Fisheries Science ISSN 2375-0715 Vol. 3 (1), pp. 185-190, January, 2015. © International Scholars Journals

Full Length Research Paper

Evaluation of varying stock densities on development and productivity of Nile tilapia Oreochromis niloticus

^*1Nana Kwesi Wood, Geogina Buari² and Heward Kofi Mahama³

¹Department of Fisheries, Wetlands and Wildlife Management, University of Ghana, Legon, Ghana.

²Department of Zoological Sciences, University of Cape Coast, Cape Coast, Ghana.

³Department of Fisheries, Wetlands and Wildlife Management, Ashesi University, Accra, Ghana.

Email: [email protected]

Accepted 4 December, 2014

Abstract 

A one month trial of sex reversal treatment of O. niloticus fry of varying stocking densities was performed in hapas-in-pond to determine the growth performance characteristics and profitability. Larvae were selected, collected, weighed and stocked inside a 10.0 m² hapas in a 0.2 ha pond with stocking densities of 10000 (A), 15000 (B) and 20000 (C). Each stocking were made in triplicate. Fry were fed with a 36% crude protein plus hormone incorporated feed five times a day. Weekly samplings of fry were done including water quality parameters. Final average body weights of treated fry were 0.226 ± 0.02, 0.125 ± 0.02 and 0.080 ± 0.01 g for treatments ‘A’, ‘B’, and ‘C’ stocks respectively. The fry growth in treatment ‘A’ was significant (at p < 0.05) among all other stocks. It also exhibited high specific growth rate and a lower feed conversion rate than others; however, high survival was achieved with fry in treatment ‘B’. High value of fry crop was achieved in treatment ‘C’ with a value of GH¢ 638.96. Although profit index did not vary significantly from each other, the treatment ‘B’ reached the highest value of 23.13 ± 9.01. The increasing fry stocking density of fry significantly affected the growth and feeding conversion rate, however, it did not affect the survival data. Due to the high profit index, relatively high growth rate and high survival, treatment ‘B’ is recommended for fry rearing in a 10.0 m² hapa-in-pond system.

Key words: Nile tilapia, hormonal feed, specific growth rate, profit index, feed conversion rate.

African Journal of Fisheries Science Vol. 2 (9), pp. 176-184, September, 2014. © International Scholars Journals

Full Length Research Paper

Spawning migration of Labeobarbus species of Lake Tana to Gilgel Abay River and its tributaries, Blue Nile Basin, Ethiopia

Dagnew Mequanent¹, Minwyelet Mingist², Abebe Getahun³ and Wassie Anteneh⁴

¹Amhara Design and Supervision Works Enterprise, P.O.Box1921,Bahir Dar, Ethiopia.

²Department of Fisheries, Wetlands and Wildlife Management, College of Agriculture and Environmental Sciences, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia.

³Department of Zoological Sciences, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.

⁴Department of Biology, College of Science, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia.Email:  [email protected]

Accepted 31 July, 2014

Abstract 

Fish samples were collected by using monofilaments gillnets (5-55 mm) and multifilament gillnets, having mesh sizes of six, eight, ten, twelve and fourteen centimeter stretched bar mesh, having a length of twenty five meter and depth of one and half meter, on six sampling sites of Gilgel Abay River and its tributaries. Dissolved Oxygen, water temperature, pH, conductivity, total dissolved solids and water transparency were measured. Samples were collected bimonthly from August to October and monthly in November. When all catches are pooled, 89.30% was contributed by the genus Labeobarbus and the remaining (5.7%) and (5%) were from the genera Clarias and Varicorhinus, respectively. Labeobarbus intermedius was the most dominant (50.10% by number), followed by L. brevicephalus (17.16%) and L. nedgia (8.58%). Spatial distribution patterns of the most abundant Labeobarbus species did not show significant variation (P >0.05). Temporal segregation among dominant Labeobarbus species was not also evident (P >0.05) except, between L. intermedius and L. brevicephalus. All Labeobarbus spp. except L. dainellii, L. gorguari, L. acutirostris and L. megastoma were found in all sites. Illegal fishing activities were rampant and must be totally prohibited by closing fishing during the spawning months to protect these unique migratory riverine spawning species.

Key words: Conservation, segregation, abundance, temporal, Labeobarbus, migration.

African Journal of Fisheries Science Vol. 2 (9), pp. 168-175, September, 2014.© International Scholars Journals

Full Length Research Paper

Assessment of genetic variation of wild rohu Labeo rohita (Hamilton 1822) populations using microsatellite markers

Umma Salma Tonny,  Abdullah Al Faroque,  Rafiqul Islam Sarder¹ and  Fazlul Awal Mollah

Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh. E-mail: [email protected]

Accepted 3 April, 2014

Abstract 

For genetic improvement and management of stocks of the Indian major carp, Labeo rohita, assessment of genetic variation of wild stocks is essential. Six dinucleotide microsatellite loci Lr3, Lr12, Lr14b, Lr21, Lr24 and Lr26 were analyzed to test the genetic variability of three populations of L. rohita collected from three different rivers, the Halda, the Jamuna and the Padma, and the analyzed loci were found to be polymorphic (P₉₅) in all the populations. The average number of allele was highest (4.16) in the Jamuna population followed by the Halda (3.66) and the Padma populations (3.16). The average observed heterozygosity (0.633) was highest in the Padma population while the highest average expected heterozygosity (0.607) was obtained in the Jamuna population. Relatively low level of F_ST (0.034) and high level of N_m (7.043) was detected between the Jamuna and the Padma populations, while high level of F_ST (0.068) and low level of N_m (3.417) was detected between the Halda and the Padma populations. The Nei's (1972) genetic distance (D) between the Halda and the Padma populations was the highest (0.167) while that was the lowest (0.073) between the Jamuna and the Padma populations. The results indicated a relatively low level of genetic variation among the wild stocks of L. rohita and suggested that necessary measures need to be taken for its stock improvement and conservation.

Key words: Labeo rohita, wild population, genetic variation, microsatellite, conservation.

African Journal of Fisheries Science Vol. 2 (9), pp. 162-167, September, 2014. © International Scholars Journals

Full Length Research Paper

Seasonality and Occurrence of parasites of fish in Agulu Lake, Southeast, Nigeria

George Davison, Victor Sebastian and Lebechi

Aquaculture Division, Nigerian Institute for Oceanography and Marine Research, P.M.B. 12729, Victoria Island, Lagos, Nigeria. Email: [email protected]

Accepted 20 August, 2014

Abstract 

A study was undertaken to assess the prevalence, mean intensity, abundance and seasonality of parasites of fish in a natural, freshwater, tropical lake, southeast Nigeria. A total of 1191 fish specimen belonging to four families (Cichlidae, Bagridae, Hepsetidae and Channidae), seven genera and nine species were collected from the lake and examined for parasites. Eleven (11) species of parasites comprising metacercariae of three digenetic trematodes, one cestode, five nematodes and two acanthocephalans were isolated. Clinostomoides sp. showed the highest range of sites of infection, and the operculum carried significantly more worm burden (F = 196.843, d.f. = 5, p = 0.000) than other sites infected by this parasite. Prevalence ranged from 0.7% in Clinostomum tilapiae infection of T. zillii to 71.7% in Neochinorhynchus sp.2 infection of Hepsetidae fasciatus with an overall prevalence of 59.5%. Mean intensity ranged from 1.0 ± 0.0 in Clinostomoides sp. and Proteocephalus sp. infection of P. obscura and Anemone occidentalis, respectively, to 76.5 ± 29.7 in Neoechinorhynchus sp. 2 infection of H. fasciatus. Neoechinorhynchus sp. 2 infection also had the highest mean abundance (54.90 ± 2.74) while the lowest was recorded in the Clinostomoides sp. infection of H. fasciatus. Patterns of infection were significantly different in the prevalence and abundance of Clinostomoides sp; Camallanus sp.3 and Neoechinorhynchus sp.1 while mean intensity was comparable in all cases.

Key words: Natural lake, freshwater, fish parasites, worm burden.

African Journal of Fisheries Science Vol. 2 (9), pp. 155-161, September, 2014. © International Scholars Journals

Full Length Research Paper

The effect of various stock densities of bottom feeder fish Cirrhinus mrigala and Cyprinus carpio on growth performance and fish yield in polyculture system

Hasnain O. Altaf, Farhanullah k. and Fahim Jahanzeb

Department of Fishery, Faculty of Agricultural Sciences, Allama Iqbal Open University, Islamabad, Islamabad CT, Pakistan.

Accepted 08 August, 2014

Abstract

The present project was planned to study gradual replacement of Cirrhinus mrigala with Cyprinus carpio and its impact on pond ecosystem. A total of 900 fishes belonging to six species viz. Catla catla, Labeo rohita, Cirrhinus mrigala, Ctenopharyngodon idella, Hypophythylmichthys molitrix and Cyprinus carpio were stocked in four earthen ponds. The dimensions of each pond were 220 × 198 × 7 feet length, breadth and depth. The stocking density in pond 1 (T1) was C. catla 150, L. rohita 200, C. mrigala 200, C. idella 150, H. molitrix 150 and C. carpio 50. The stocking density of C. mrigala and C. carpio in pond 2 (T2) was 150 and 100, in pond 3 (T3), 100 and 150 and in pond 4 (T4) it was 50 and 200, respectively while the stocking density of all the other four fish species remained constant in all the four ponds. All the fish were fed with a diet of 25.16% crude protein at 2% body weight. C. idella and C. mrigala showed maximum growth in T1, C. catla and H. molitrix in T2, L. rohita and C. carpio in T3. Maximum growth was observed in T3 followed by T4, T1 and T2. Among fish species C. idella and C. carpio showed higher growth rates than the rest of fish species. Our results reveal that in polyculture system stocking density of C. mrigala and C. carpio in a ratio of 1: 1.5 gives better results.

Key words: Aquaculture, freshwater, phytoplankton, zooplankton, exotic fish.

African Journal of Fisheries Science Vol. 2 (8), pp. 148-154, August, 2014. © International Scholars Journals

Full Length Research Paper

Assessment of effects of water quality of physicochemical parameters of waste water from rainbow trout fish farms Koohrang stream – Iran

Masuod Soheilfarid Ehsan, Hooman Sadeghi and Qadamgahi Rahimi

Department of Aquaculture and Fisheries Management, Faculty of Agriculture, Golestan UniversityGorgan, Golestan, Iran. Email: [email protected]

Abstract

Physicochemical parameters of rainbow trout farm water were evaluated to assess the potential of fish farm effluents on stream water quality. Seven fish farms were selected at Rostamabad region located on 70 km at south-west of Shahrekord-Iran. Water samples were collected from fish farms inlet and outlet at first and second sampling point. Significant differences were observed in some water factors such as total hardness, total dissolved solid, total suspended solid, COD, BOD₅, dissolved oxygen, phosphate, nitrite, nitrate and total ammonia between inlet and outlet water of fish farms where as there were no significant changes in pH, sodium chloride and water temperatures. All of the water factors because of self-purification potential of the stream were in desirable amounts in third sampling point. Feasibility study carried out to assess the distance for making consecutive fish farm along the stream. It was observed that it is possible to make consecutive fish farms at around 1500 m distance but it is depended on stream water discharge and self-purification of the stream.

Key words: Water pollution, trout farm effluents, environmental impact, Koohrang stream.