Open Access Volume 7 • Issue 6 • 1000431 J Aquac Res Development ISSN: 2155-9546 JARD, an open access journal Open Access Mapenzi and Mmochi, J Aquac Res Development 2016, 7:6 DOI: 10.4172/2155-9546.1000431 Open Access Keywords: Hybrids; Mariculture; Growth performance; Salinity; All males Introduction Salinity is defned as the sum of all ions in water which comprises mainly of sodium, chloride, calcium, magnesium, potassium, bicarbonate and sulfate ions [1]. Salinity is a vital water quality parameter for fsh growth [2]. Küçük et al. reported on retarded fsh growth at diferent saline conditions. Fish in marine or freshwater environments use energy to hold ions in or of their bodies respectively through osmoregulation [1]. Some studies indicate better fsh growth in brackish water than Full Strength Sea Water (FSSW) and fresh water [3-6]. However, the salinity acclimation process forces fsh to undergo endocronological, morphological and biochemical changes [1]. Te modifcations interrupt both energy and oxygen intake in fsh. Some experiments were conducted on length-weight relationship and condition factor for Tilapia zilli and O. urolepis urolepis at FSSW and fresh water [7], efect of diferent salinities on growth and survival of O. niloticus [8] and Oreochromis aureus [1] (Küçük et al. 2013). Yet no attempt has been made to assess efect of salinity on O. niloticus♀ x O. urolepis urolepis♂ hybrids growth performance. Tere is a general agreement that hybrids derived from salinity tolerant parents are salinity tolerant [9]. Also, O. niloticus has proven high growth and bigger size at maturity among tilapiine species while O. urolepis urolepis has high salinity tolerance but low growth rates at maturity. Terefore, hybrids are expected to have high growth rates and salinity tolerance than their parents. Tis study investigated the efect of diferent salinity levels on growth performance of the hybrids between O. niloticus females and O. urolepis urolepis males. Te aim was to produce all male fsh tolerant to varying salinity conditions for improvement of aquaculture along the Tanzanian coastline through intensive and semi intensive mariculture. Materials and Methods Description of the study site Tis study was conducted at the Institute of Marine Sciences Mariculture Centre (IMS-MC) at Bweni village, Pangani District in Tanga Region, Tanzania (05 ° 26´ 0˝ S and 38 ° 58´ 0˝ E, Figure 1). Local communities’ main economic activities involve fshing, seaweed aquaculture and subsistence agriculture. Te site is drained by Pangani River whose basin is bordered by the Kilimanjaro and Meru Mountains and Pare and Usambara Mountain Ranges. It is well endowed with several species of terrestrial and marine ecosystems including mangroves. Te Pangani River has a diversity of tilapia species including O. pangani korogwe, O. pangani pangani, O. Variabilis, T. rendalli and T. zillii. Pangani is characterized by annual rainfall of above 1000 mm with temperature varying between 25 ° C and 30 ° C. Te climate is generally warm and wet annually. Te O. urolepis urolepis and O. niloticus broodstocks were collected from Rufji River in the Central Eastern Tanzania draining into Indian Ocean and Lake Victoria in Mwanza respectively. Experimental design and hybrids stocking An experiment with three levels of salinity was conducted. Te experiment was replicated three times making a total of 12 tanks including the controls. A total of 120 fry were batch weighed prior to stocking and randomly distributed at 10 fsh per tank. Te initial average weights were found to be 0.29 ± 0.01g per treatment. Acclimation to diferent salinities was done through daily increments of 2 PSU [7] for 17 days before the start of experiment (Figure 2). Water quality parameters were measured before and afer sea water addition in tanks. Furthermore, pH and temperature measured by HI8424 pH meter, salinity by Digital Hand Held Marine Tester DMT-10 and DO by a Dissolved Oxygen Meter PDO-520 were measured once a week. *Corresponding author: Levinus Leonard Mapenzi, Department of Biotechnology and Bioinformatics, P.O. Box 338, the University of Dodoma, Tanzania, Tel: +255715230920; Fax: +255 262310005; E-mail: levinus@yahoo.com Received May 10, 2016; Accepted June 14, 2016; Published June 16, 2016 Citation: Mapenzi LL, Mmochi AJ (2016) Role of Salinity on Growth Performance of Oreochromis niloticus♀ and Oreochromis urolepis urolepis♂ Hybrids. J Aquac Res Development 7: 431. doi:10.4172/2155-9546.1000431 Copyright: © 2016 Mapenzi LL, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Infuence of salinity on hybrids descended from O. niloticus♀ and O. urolepis urolepis♂ was investigated for 63 days. A total of 120 fry of 0.29 ± 0.01g were stocked in 1m 3 plastic tanks at a density of 10 fsh/m 3 per tank. The experiment involved three salinity treatments 15, 25 and 35 with fresh water (2 salinity units) as control. The hybrids were fed on a balanced diet of 40% crude protein at 5% body weight twice a day. Water quality parameters were measured once a week. However, results on SGR, average weight gain and survival rate were not signifcantly affected by salinity (p>0.05). FCR differed signifcantly among treatments (p<0.05). The 25 Practical Salinity Unit (PSU) showed better growth performance than other treatments. Surprisingly all treatments showed better growth than control. When examined at the end of the study all hybrids were found to be 100% males. Length-weight relationship “b” values and condition factor “K” showed that hybrids had isometric growth, good health and were properly managed. It was concluded that if proper management is followed, the studied hybrids can be good candidates in both intensive and semi intensive mariculture by coastal people. The hybrids can solve the problem of stunted growth, be an alternative to the use of hormones in sex reversal. Role of Salinity on Growth Performance of Oreochromis niloticus♀ and Oreochromis urolepis urolepis♂ Hybrids Levinus Leonard Mapenzi 1,2 * and Aviti John Mmochi 2 1 Department of Biotechnology and Bioinformatics, University of Dodoma, Tanzania 2 Institute of Marine Science, University of Dar es Salaam, Zanzibar Journal of Aquaculture Research & Development Research Article J o u r n a l o f A q u a c u lt u r e R e s e a r c h & D e v e l o p m e n t ISSN: 2155-9546