Adaptation, growth and survival of tilapia (Oreochromis niloticus) in Bafgh brackish water

An experiment was conducted to evaluate the possibility of adaptation, growth and survival of Nile tilapia (Oreochromis niloticus) with 0.3g initial weight and red tilapia (Oreochromis sp.) with 0.7g initial weight in underground brackish water. Fry of Nile tilapia and red tilapia imported from Indonesia and after passing larviculture (25g) were examined separately in fiber glass tank by two replicate. Fish were fed at a restricted feeding program according to standard table during the light period. The results showed that some growth factors such as final weight, final length, daily growth rate, specific growth rate and weight gain in Nile tilapia were slightly higher than red tilapia but other factors such as survival and feed conversion rate in red tilapia were slightly higher than Nile tilapia. There were no significantly differences at 99% level among these factors. Length-weight relationship equation was w = 0.012×TL3.189 in Nile tilapia and w = 0.014×TL3.119 in red tilapia (r2 = 0.99), b value were 3.189 and 3.119 respectively in Nile and red tilapia representing isometric growth. According to the reliable growth and high survival rate (98%), it seems that both Nile and red tilapia could be good candidates for rearing in brackish water condition

Investigation of Litopenaeus vannamei culture in brackish waters of Bafgh, Yazd Province

This survey is part of the investigation on feasibility of introduction of Litopenaeus vannamei Boone, 1931 in shrimp culture industry of Iran. The objective was evaluation of the adaptation of the white leg shrimp, L. vannamei to brackish groundwaters of the Bafgh area in Yazd province. Around 120000 shrimp postlarvae (PL7 and 15) were stocked in four 0.15ha earthen ponds (17 and 23 ind/m ^(2)) in July 2005 and the culture period took about four months. Physicochemical and biological factors were studied during the culture. Shrimps were fed with commercial feed of the L. vannamei. Results showed low survival (19.2%) and growth (2-2.5g mean body weight). Based on the assessments, the limnological factors were most unfavorable elements causing the low growth in the shrimp. Concentration of K, Ca, Mg and Na Fe (II and III), different heavy metals, nitrogenous compounds, water hardness and the season and thermal periods are probably the most essential factors affecting production yield of the shrimp because of underground origin of the water. Also, the structure of ponds and drainages, presence of invasive water plants and insects may have affected the survival and growth of the shrimp as well

An investigation on all male production of nile tilapia (Oreochromis niloticus) under the condition of brackish water in Bafgh

This study was aimed to investigate the effects of different doses of two hormones and an anti-aromatase, i.e. 17a methyl testosterone (MT), methyl di hydrotestosterone (MDHT) or mestanolone and letozole in masculinization of Nile tilapia (Oreochromis niloticus) under the condition of brackish water in Bafgh station situated in Yazd province in center of Iran. Each experiment in this study was consisted of 5 treaments with 3 replicates each. A number of 1725 larvaes was distributed randomly among 15 replicates at the beginning of each experiment. Each experiment lasted 45 days and the larvaes were reared in aerated flow-through pots and fiberglass tanks filled with brackish water. The averages for temperature, salinity, pH and dissolved oxygen of water were 26.9 ê, 8 g/l, 7.6 and 5.78% respectively during this study. In experiment 1, three different doses of 40, 60 and 100 mg MT/k of feed were fed to different groups of 7 day post fertilization (dpf) larvaes for 45 days from the beginning of the experiment. The results showed that the larvaes in 40 mg group were 100 percent masculinized based on squash test performed at the end of the experiment but masculinization rates of those in 60 and 100 mg groups were 99.7 and 96.2 perecent respectively. Based on Dunkan test, total body length and weight averages measured in biometry 3 (at the end of the experiment) were not significantly different among groups but in biometry 2 (30 days after the beginning of experiment), they were significantly lesser only in 40 mg group (P<0.05). There was significant differences in survival rate of different groups of larvaes in this experiment based on chi-square test (χ=31.166, P<0.05) and the values in 40 and 100 mg groups (74.5 and 82.9% respectively) were lesser than those in 60 mg, control 1 and control 2 groups (84.3, 89.0 and 87.0 respectively). In experiment 2, masculinization rates of two different groups of larvaes immersed in 1800 µg MDHT/liter once in 10dpf and twice in 10 and 14dpf were 80.0 and 91.9 percent respectively. There were no significant differences in total body length and weight averages measured in biometry 2 between different groups but significant differences were observed in total body length only in biometry 3 (P<0.05) where the highest values occurred in experiment 1 and control 1 groups and the lowest one in experiment 2. Significant differences observed in survival rate of different groups of larvaes in this experiment based on chi-square test (χ=15.165, P<0.05) and the rates in experiment 1, control 2 and 3 groups (89.9, 86.4 and 89.9% respectively) were higher than those in experiment 2 and control 1 groups (82.0 and 82.3 respectively). In experiment 3, three different doses of anti-aromatse letrozole (200, 300 and 400 mg/k feed) were fed to different groups of 7 day post fertilization (dpf) larvaes for 45 days from the beginning of the experiment. The larvaes in 400 group .were all masculinized whereas the masculinization rates in 200 and 300 mg groups were 99.0 and 99.6% respectively. There were significant differences in total body length and weight averages measured in biometry 2 and 3 among groups in this experiment (P<0.05) where the highest and the lowest values occurred in control 2 and experime2 groups respectively. Based on chi-square, the survival rate of different groups was significantly different (χ=41.119, P<0.05) and the lowest rate occurred in experiment 2 group. No significant differences observed in gender ratios within all control groups in this study based on chi-square test. According to the findings acquired under the condition of brackish water at the present study, it would be potentially recommended to use MT and letrozole for the production of all male populations of Nile tilapia fish in order to provide fish farmers with no harmful environmental impacts on water sources in rivers and seas which occured due to the uncontroled breeding of tilapia. However, more research is needed to draw firm conclusions to use hormones and in especial anti-aromase letrozole because of the shortage of sufficient data in current references

An investigation on possibility of nile tilapia (Oreochromis niloticus) feminization under the condition of brackish water in Bafgh

This study was aimed to investigate the effect of different doses of oral diethylstilbestrol (DES) on feminization of Nile tilapia (Oreochromis niloticus) larvae under the condition of brackish water in Bafgh fisheries research center. This Experiment was comprised of two control groups in two replicates and two experimental ones in three replicates. At the beginning of the trial, a number of 2150 larvae were randomly distributed among 10 replicates that were under treatment for 45 days. The diets in two control groups, i.e. non-treated, C1, and ethanol treated feed, C2, and the ones in two experimental groups, i.e. 200 and 400 mg DES/k of feed, E1 and E2, were administrated to 7 day post fertilization (dpf) larvae for a period of 35 days and then until day 45, the larvae were fed with ordinary feed. At the end of the trial, the gender ratio of larvae in different groups was determined by squash test in 50 randomly selected individuals from each replicate. The results showed no significant differences for gender ratios within control groups (respective male to female ratio in C1 and C2 was 47:53 and 57:43). However, the corresponding ratios within experimental ones, fed with 200 and 400 mg DES/k of feed respectively, was significantly different (P<0.05). Noteworthy that the percent of females between two experimental groups (E1 and E2) was not significantly different (70.0 and 64.7 respectively) but it was significantly different with ratios in experimental groups (P<0.05). The total body length and live body weight were determined at the begging and then at day 30 and 45, it was randomly measured in 20 larvae from each replicate. At the beginning of the experiment, the mean body weight and total length of larvae was 0.012 gram and 1.03 centimeter respectively. The respective averages at day 30 and 45 were significantly different among groups (P<0.05). Survival rate was significantly different among groups (P<0.05), being highest in E1 and E2 respectively whereas lowest in control ones (56.51 and 58.84 in C1 and C2 respectively)

Environment impact assessment of tilapia (Tilapia Nilotica) farming project in brachish water of Bafgh

The aim of the present study is the environmental impact assessment of tilapia (Tilapia nilotica) farming project in brackish water of Bafgh, with goals to achieve localization of technology and knowledge of tilapia fish production, employment and the possibility to controlled development in other areas. Desired range, located in northwest of Daranjir desert (Inland Salt Water Fishes Research Station, Bafgh). Total area used for the project includes three indoor hall for breeding operation, nursery (juvenile breeding) and fattening. Besides these, three 3000 m 3 available earth ponds has been considered as a potential area breeding after setting apart the quarantine. In order to achieve sustainable development of breeding this fish, impact assessment of this project development in which both environmental and social - economic effects are considered, it seems essential and project will be accomplished more confidently. So, after considering the technical characteristics of the project, the immediate, direct and indirect impact area were determined and environmental aspects of area identified. Matrix methods was utilized for the environmental impact assessment. The most important operational activities, including greenhouse structures implementation and water conveyance facilities, including excavation and embankment, channel, piping, lining of channels and their accessories including inlet and outlet valves, concrete, stone, porcelain, walling up , roof, construction of drainage network and access roads. Based on investigation, accessibility of the region, compatibility with the other land uses, lack of monuments in the area, not covered with the sensitive habitats range, the lack of permanent river flow, low quality of underground water and end up underground water flows in downstream desert and evaporated which result in impossibility of escaping introduced fish from the farm and the use of existing spaces in the first half of the year to product lead to make fewer infrastructure costs and increase revenue, are the main criteria for the sustainable development of this species culture in the area. Considering the executed studies and results of the matrix assessment construction and operation phases, it was concluded that there is no considerable destructive impacts related to the project. Therefore due to the fact that 50% of means in rows and columns of the matrix were not less than -3.1 so, we proposed execution of it with rehabilitation plans. Therefore, some strategies and plans to consider reducing the negative effects and enhance positive effects of the project, including monitoring programs, were proposed

Biotechnics of live feed (Chironomidae) culture for using in feeding of cultured aquatics

Larvae of the chironomid midges (blood worms) are known as use full live food for cultured aquatics. There are endemic blood worms in sediments of the earthponds of Bafgh area at center of Iran. This study tended to identification of two chironomid species, Chironomus aprilinus Meigen, 1830 and Dicrotendipes sudanicus Freeman, 1959 & 1961, from Iran as a new record. Culture of blood worms was successful in glass thanks with 16h. Light, at 24-26°C temperature. Eggs were incubated after 14 days. Suitable concentration of harvesting is 1-2 egg masses (1250eggs/m2). Enrichment of earth ponds or plastic thanks including sedime is offered for culture of chironomid larvae. Collectors prepared with low cost materials are useful for collection of egg masses. May, June and July are the best time for egg collection. Large blood worms are mainly available in winter. Results of body analysis of the larvae indicated high dry matter with good quality

Evaluation of different levels of feeding and their effects on growth and FCR in grower rainbow trout in fiberglass tanks under the condition of brackish water in Bafgh station

The objective of this study was to evaluate 4 levels of feeding defined as 1.ad libitum to satiation, 2.Standard feeding (based on fish size and water temperature), 3.10% less than that of standard feeding and 4.10% more than that of standard feeding on growth, feed conversion rate (FCR) and carcass quality of rainbow trout (Oncorhynchus mykiss) reared in 12 aerated flow-through fiber glass tanks (2500l rearing volume, n=150 fish per tank, body weight average 45 g) comprised of 3 replicates under the condition of brackish water (salinity 8.4 g/l) in Bafgh Fisheries Research Station in center of Iran. The increase in average body weight (BW) and size of fish in different feeding groups was significantly different (P<0.01) during the experiment (101 days) and the highest average BW and size increase occurred in the group fed ad libitum to satiation. On the contrary, FCR (average ±SE: 1.27±0.09) in this group was statistically lower than that of the other groups (P<0.01). The chemical composition of carcass was significantly influenced by the level of feeding (P<0.01) and the percent of moisture, crude protein and ash was the lowest in the group fed ad libitum to satiation while the crude fat percent in this group was the highest of all. According to the results obtained in this study, an ad libitum feeding regime is suggested for rainbow trout production in fish culture systems of central desert regions in Iran under the condition of brackish water. However, further investigations are needed to draw firm conclusions, especially in earth pond cultures with different conditions, enriched in live food

Determine optimal diet for rearing black tilapia (Oreochromis niloticus) in Bafgh brackish water

Tilapia is one of African native fishes has been introduced to many thermal and temperate regions in the world for second part of twentieth century. First, intensive culture system dependes on complete and wide information in nutrition requirements, specially protein as most expensive nutrient; second, the importance of tilapia in future of Iran; and third, lipid as first non-protein energy source that is so influent and it’s unsufficient values affect negatively on growth and protein requirement, make us to investigating the protein and lipid requirement of Nile tilapia Oreochromis niloticus to achive a convience diet causing most economical interest by maximum growth and minimum feed conversion ratio. This experiment performed in Bafgh Inland Saline Water Fish Research Station. It was planned in four protein (15, 22, 29 and 36%) and three lipid (5, 9 and 13%) levels in factorial system. Thirty six 300 l tanks with 150 l water and 3 l/min water flow used for 12 treatments with triplicates. 15 male Nile tilapia fingerlings (13.94±0.88 g) kept in every tank and fed near satiation during 8 weeks experiment. There was any significant different in survival in all treatments. Growth performance (WG & SGR), feed and protein efficiency (FCR & C and PER & PCE respectively) improved with increasing proein level until 29%, however, significant positive effect was not observed by lipid increasing. Then, best economical protein and lipid level for convinienc growth performance and protein and lipid efficiency is 29 and 5% respectively. In 5% lipid, maximum growth and protein efficiency appears between 33.9 to 35.3% protein according to the mathematical method (polynomiyal curve)

Improvement of black tilapia (Oreochromis niloticus) diets with replacement of low-cost, native materials

Fish meal production has been fixed in the world because of a limitation in fish stocks. On the other hand, demand of fish meal is growing daily and consequent the cost, too. Therefore, attention to the other protein sources is nessesary. Some plant protein sources, especially oilseeds, have valuable potentials for replacing fish meal because of relative high production in the world and Iran and low cost. According to existing information and availability, cottonseed meal and canola meal were selected as oilseeds; and Azolla was considered whether to be controlled in north provinces of Iran as weed. Growth indices (WG and SGR), food (FCR) and protein efficiency (PER and PCE) of fingerling Nile tilapia Oreochromis niloticus were evaluated in 3 synchronous examinations with 12 treatments and 36 replications. Groups of control, canola meal (at rates of 25, 50, 75 and 100%), cottonseed meal (at rates of 15, 25, 35 and 45%), as the replacements of expensive protein sources (fish meal and soybean meal), and azolla (at rates of 13, 21 and 29% of diet) were studied. Growth indices, total food intake and protein intake of control group were higher than all diets contained plant protein sources. They decreased with plant protein increasing in every grous, separagely (p0.05) between control and canola meal (at rates of 25 and 50%), cottonseed meal (at rates of 15, 25 and 35%) and azolla (at rates of 13 and 21%). All plant protein ingredients were unpalatable, and consequent total food intake, protein consumption and growth decreased. It will be expected that Canola meal and cottonseed meal replace expensive protein sources at the rates of 50 and 35% respectively, and azolla use at the rate of 21% in diets If the problem in palatability solves

Raising economical efficiency of tilapia culture (Oreochromis sp.) by using the best stocking density in brackish water earthen pond

An experiment was conducted to evaluate the effect of stocking density on growth and survival of Nile tilapia (Oreochromis niloticus) in earthen pond. Fish with 13 g initial weight examined in three treatment 3, 6 and 9 fish/m^2 in duplicates. Fish were fed on rainbow trout commercial food during the 105 days of culturing period at a restricted feeding program according to standard table during the light period. The results showed significant reduction in final weight, weight gain, daily growth rate, specific growth rate and survival by increasing stocking density while feed conversion rate increase by increasing stocking density( P < 0.05). The treatment 3 fish/m^2 resulted the best growth rate (3.24 %/day) and survival (94.8 %), and the lowest feed conversion rate (0.51). So it seems that to achievement the highest profitability in earthen pond the 3 fish/m2 treatment is suitable