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Treatments 4

Live feed

Plant feed

-

5

Treatments 5

Live feed

Plate of feed

-

6

Treatments 6

Plant feed

Plate of feed

-

7

Treatments 7

Live feed

Plant feed

Plate of feed

Results

Overall results are presented in Table 4. In this table it can be seen that the average number of treatments 1 195 eggs have been collected. In treatment 2 187 eggs and treatment 3, 178 in treatment 4, 197 and treatment 5, 198 and treatment 6 186 and the number of eggs treated 7, 202 eggs is collected. Average number of eggs from each treatment consisted of 10 female ovipositor with two repeat is ready.

Table 4: Results of eggs obtained from different treatments

Row Treatments Number of eggs

1

Treatments 1

195

2

Treatments 2

178

3

Treatments 3

187

4

Treatments 4

197

5

Treatments 5

198

6

Treatments 6

186

7

Treatments 7

202

Discussion

One that only live food is used in the treatment of eggs. The number 195 was collected in the second treatment plant foods Plate 3, which has been used and treated further and shows the use of live food in the

production has of king prawn spawning a better outcome.

Food of the plate which is used in treatment 3 better the only food that than treatment 2 is used achieved. It also has better results than treatment 5 Treatment 4 and treatment 5 live food and plates used in the Achieved better results than treatment 4. Treated 6 well Herbal ingredients and plates of food that is alive and Plant have achieved little result.

Finally, the combination of live food and plant food 3 food and plates has achieved better results than all other treatments. It shows a live feed of all treatments is important. The next result shows that the use of plant foods is incomplete and requires other ingredients. The next result shows that the use of plant foods need not be perfect the other ingredients are. The final result shows that salmon dish meals Cray fish brood stock fully comply with the requirements of food is not necessary can not find a better formulation of fish diets. In fact, food Cray fish brood stock for specific material design and results get better.

Suggestions

Using the results obtained in this study appears to be due to the greater number of crayfish eggs need to multiply the following appears.

1. If you need more research on methods that can be done in brood stock female crayfish eggs.

2. King prawn feed formulation and food components required for a wider investigation will be conducted.

3. The production of live food for crayfish more work to be done in terms of research.

Reference

Breeding of freshwater crayfish. Knowledge through publications. Page 98.

Alginates as Binders Smart, H. 1,380. Biology and for Crustacean Diets. 1972. World mariculture Society.351-364.

Shelly, C. Lovatelli, A. 2001. Mud crab aquaculture. Fao ( Fisheries and Aquaculture Technical papers ). No.576. Rome Italy. 78P.

Thiamine deficiency in Sterlet sturgeon (Acipenser ruthenus) larvae

Sareh Ghiasi1, Bahram Falahatkar1*, Alireza Abasalizadeh2, Konrad Dabrowski3

1 Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, 1144, Guilan, Iran email: falahatkar@guilan.ac.ir

2 Shahid Dr. Beheshti Sturgeon Fish Propagation and Rearing Complex, Rasht, Guilan, Iran

3 The School of Environment and Natural Resources, The Ohio State University, Columbus, 4З210, USA

Introduction

Sturgeons are the most valuable fish species because of their meat quality and high nutritional value of caviar. Because of the decrease in natural stocks, many species of sturgeons are listed as endangered by IUCN. The availability of high quality diets for broodfish is the main factor affecting the ovarian development and further larval and juveniles quality (Palace and Werner, 2006). Micronutrients such as thiamine (vitamin B1) is important in early life stages of fish (Fitizsimons et al; 2007; Lee et al., 2009). In this regard, some diseases including early mortality syndrome (EMS) were identified as a result of thiamine deficiency leading to major mortality in early life stages (Tillitt et al., 2005). Because in the natural environment, some food items of sturgeon like alewife contain thiaminase, an enzyme which destroys thiamine, and this may contribute to a reduced sturgeon larvae viability.

Larval and fingerlings sterlet is produced from wild or domesticated broodfish for either rehabilitation or aquaculture purposes. In this case, sterlet is a good species for the study of some questions on the reproductive performance because of earlier puberty in comparison to other species. This study aimed to examine the effects of thiamine deficiency or enrichment in the diet of sterlet on reproductive performance, larval viability and deficiency signs in larvae.

A total of 45 farmed female sterlet with average weight of 697.8 ± 8.9 g and same maturity stage (nucleus migration) were transferred to 9 fiberglass tanks (2 x 2 x 0.5 m) in three treatments (with 3 replications for each). During the experimental period, average temperature and dissolved oxygen were 9.8 ± 0.3°C and 7.5 ± 0.2 mg/L, respectively. Experimental diet was prepared to contain 43% protein and 13% fat and 1g/kg amprolium hydrochloride as an anti thiamine (Fynn-Aikins et al., 1998). Fish were fed 0.5% of body weight daily for 5 months. The levels of thiamine in each treatment that was injected to each fish were 0 (T0), 5 (T5), 50 (T50) mg/kg body weight. Thiamine was mixed in 0.9% physiological saline solution and the pH of solution was fixed at 7 by 10 M NaOH. During the experiment, thiamine was injected intraperitoneally 3 times, on days 30, 90 and 150. At the end of 5 months, feeding was stopped and after 2 weeks based on the polarization index (Dettlaff et al., 1993) and water temperature, fish were injected 2.5 mg/kg LHRHa2 in two doses with the 12 hours interval (10% as priming dose and 90% as resolving dose). During the final maturation and ovulation, the eggs were obtained by cesarean method (Falahatkar and Efatpanah, 2011). Eggs were fertilized with mixed sperm (n = 3 males) according to the semi-moist method. The adhesion of the fertilized eggs was removed by clay solution and rinsing with water. Then the eggs of each fish were transferred to a small container (12 x 10 x 10 cm2) placed in the Yushchenko incubators. To calculate the number of eggs per gram, 2 grams of eggs were taken from each fish and eggs were counted. At the end of incubation, hatching rate also was calculated. After hatching, a sample of 200 larva were transferred to three separate tanks for further weight, length and some deformities analysis. At 0 and 6 days post hatch (dph), length and weight of 30 larvae were measured. Behavior related to deficiency signs were monitored daily. Dead or deformed larvae were removed and counted every day. Data were analyzed by SPSS 16, with one-way ANOVA and Tukey's test at the level of 95%.

Results showed that there were significant differences in hatching rate (p<0.05), but no significant differences were observed in number of eggs/g (Table; 1, p>0.05). The highest and lowest mortality was observed in T5 and T50 treated fish, respectively (p>0.05). The results of larval weight showed significant differences among the treatments at 0 dph and 6 dph. The maximum length and weight was in T50 and lowest in the T0 (p<0.05). During the daily monitoring of dead or deformed larvae, symptoms were observed in T5 treatment on day 4 that included poor growth, deformed yolk sac, lack of absorption of the yolk sac, and imbalance and swirling behavior.

Table 1. Hatching and larval performance of sterlet broodstocks fed anti thiamin and injected with different levels of thiamin after 5 months rearing (n=15 broodfish/treatment; mean ± SE)

Treatment (mg/kg BW)

no. eggs/g

Hatching rate

(%)

Larval length at 0 dph (mm)

Larval weight at 0 dph

(mg)

Larval length at 6 dph

(mm)

Larval weight

at 0 dph

(mg)

Larval mortality

(%)

T0

124.38 ± 5.59

71.2 ± 0.12 a

10.43 ± 0.07 b

10.7 ± 0.00 c

15.33 ± 0.09

21.6 ± 0.00 c

15.1

T5

127.03 ± 6.42

45.1 ± 0.15 b

9.66 ± 0.10 c

11.4 ± 0.00 b

15.38 ± 0.13

21.7 ± 0.00 b

40.0

T50

118.43 ± 6.61

66.5 ± 0.17 a

10.80 ± 0.07 a

11.6 ± 0.00 a

15.62 ± 0.14

23.1 ± 0.00 a

3.9

Discussion

This study showed that thiamine has positive effects on larval size in 0 dph and 6 dph. Results from similar studies suggest that when Salmo salar broodstock was fed anti thiamine before the spawning, thiamine level in eggs was lower than to fish fed control diet (Fynn-Aikins et al., 1998). This reduction in egg thiamine caused poor growth rate and lowered weight of larvae (Fitzsimons et al., 2009). Coho salmon (Oncorhynchus kisutch) breeders that were fed diets containing anti thiamine and followed with the injection by thiamine showed increasing thiamine levels in the eggs (Fitzsimons et al., 2005).

Our results showed that the lowest and highest number of eggs was in

fish treated with T50 and T0, respectively, and it seems that fish that have received high dose of thiamine, it can produce larger eggs compared to other treatments. Also, mortality was reduced in fish treated with T50 and this is perhaps because of the high concentration of thiamin in the eggs. Lee et al (2009) showed that when thiamin decreases in eggs, survival rate is reduced and mortality in larvae reaches to 94-100%. Ketola et al (2000) showed that injection of 7 mg/kg thiamine before spawning, reduced larval mortality and EMS in brood fish.

In the present study in fish treated with T5 at 4 dph, some signs of EMS, including poor growth, lack of absorption of yolk sac, erratic swimming and loss of equilibrium, deformed yolk sac and high mortality were observed. These kinds of symptoms were also observed by Norrgren et al. (1993) in salmon. The lack of such signs in fish that were fed anti thiamine and treated with T0 was not expected and more studies are needed to find why this deficiency could not demonstrate in other affected fish. Thiamine has a coenzyme role in carbohydrate metabolism and it is important in glucose synthesis, particularly in nervous and brain tissues. The nervous disorders caused the fish to lose equilibrium and become sensitive to environmental shocks. Our results revealed that thiamine injection has a positive effect on growth and larval survival, and injection of thiamine in the sturgeon breeders can reduce the negative impacts of anti thiamine in natural environment.

References

Dettlaff, T.A., Ginsburg, A.S. and Schmalhausen, O.I., 1993. Sturgeon fishes: Development Biology and Aquaculture. Springer Verlag, New York, 300p.

Falahatkar, B. and Efatpanah, I. 2011. Egg extraction of sterlet sturgeon, Acipenser ruthenus L, through surgery. Journal of Veterinary Research, 66: 349-353.

Fitzsimons, J.D., Williston, B., Amcoff, P., Balk, L., Pecor, C., Ketola, G., Hinterkopf, J.P. and Honeyfield, D.C. 2005. The effect of thiamine injection on upstream migration, survival, and thiamine status of putative thiamine deficient coho salmon, Journal of Aquatic Animal Health, 17: 48-58.

Fitzsimons, J.D., Brown, S.B., Williston, B., Williston, G., Brown, L.R, Moore, K., Honeyfield, D.C. and Tillitt, D.E. 2009. Influence of thiamine deficiency on lake trout larval growth, foraging, and predator avoidance, Journal of Aquatic Animal Health, 21: 302-314.

Fynn-Aikins, K., Bowser, P., Honeyfield, D., Fitzsimons, J. and Ketola G. 1998. Effect of dietary amprolium on tissue thiamin and Cayuga syndrome in Atlantic salmon. Transactions of the American Fisheries Society, 127: 747-757.

Izquierdo, M.S., Fernandez-Palacios, H. and Tacon, A.G.J. 2001. Effect of broodstock nutrition on reproductive performance of fish. Aquaculture, 197: 25-42.

Ketola, G., Bowser, P.R., Wooster, G.A., Wedge, L.R. and Hurst, S.S. 2000. Effects of

thiamine on reproduction of Atlantic salmon and a new hypothesis for their extirpation in lake Ontario. American Fisheries Society Symposium, 129: 607­612.

Lee, B., Jaroszewska, M., Dabrowski, K., Czesny, S. and Rinchard, J. 2009. Effects of vitamin B1 (thiamin) deficiency in lake trout alevins and preventive treatments. Journal of Aquatic Animal Health, 21: 290-301.

Norrgren, L., Anderson, T. Bergqvist, P.A. and Bjorklund, I. 1993. Chemical, physiological, and morphological studies of feral Baltic salmon (Salmo salar) suffering  from  abnormal  fry mortality.  Environmental  Toxicology and

Chemistry, 12: 2065-2075.

Palace, V.P. and Werner, J. 2006. Vitamins A and E in the maternal diet influence egg quality and early life stage development in fish. Scientia Marina, 70: 41-57.

Tillitt, D.E. and Zajicek, J. 2005. Development of thiamine deficiencies and early mortality syndrome in lake trout Salvelinus namaycusch by feeding experimental and feral fish diets containing thiaminase. Journal of Aquatic Animal Health, 17:

4-12.

Study of the effects of Dunaliella salina as a natural /?-carotene source on pigmentation, survival and growth, in the larval Angel fish (Pterophyllum scalare)

Mahmoud Ghobadi1, Mohammad Ali Nematollahi1*

1 University of Tehran, College of Agriculture and Natural Resources, Department of

Fisheries, karaj, Iran. * Corresponding author: malahi@ut.ac.ir

Abstract

Microalgae, which are important in the production of larval fish because of their nutritive ingredient, can be used as a natural pigment source in fish feeds. The use of microalgal biomass has been recently investigated with regard to its potential as a colouring agent. But the use of synthetic pigment sources is more common because they are easy to obtain. In this study, we have investigated the effects of Dunaliella salina (Chlorophyta) as a natural /^-carotene source and astaxanthin as synthetic pigment sources on the skin colour of the larval Angel fish, Pterophyllum scalare. The fish were fed diets containing 50 mg kg-1 astaxanthin and D. salina powder. The amount of both natural and synthetic pigment sources given as feed was 50 mg kg-1, and the experiment was continued for 60 days. Total carotenoid content of the fish was determined spectrophotometrically at the end of the experiment. As a result, while a visible change of colour in the skin of the fish fed on the feed containing astaxanthin was observed with 0.31 ± 0.03 mg g-1 of pigment accumulation, a relatively small change of colour was observed in the skin of other fish that were fed on the feed containing D. salina with 0.24 ± 0.01 mg g-1 of pigment accumulations, respectively. Therefore, it was determined that these pigment sources (Dunaliella salina) have an effect on the colour of the larval Pterophyllum scalare. Keywords: Dunaliella salina, Pterophyllum scalare, pigment, astaxanthin.

The Angel fish (Pterophyllum scalare) that was studied is one of the most preferred species. it is widely popular in world. The Angel fish skin comes in many very different colour combinations. For example, while male have shiny and beautiful colours, females have less vivid colours. Since consumers prefer males, females are transformed into males using hormones so that they become more colourful. It is both possible and more useful to use microalgae or synthetic colorants. Because, in addition to affecting the skin colour of fish, these materials strengthen the immune system of fish and help them grow faster (Tanaka et al. 1976; Tacon 1981). But there is not sufficient information on which material and which dose are optimum for the sole reason that these subjects are not attractive for researchers.

One of the most attractive features of aquatic creatures is arguably their brilliant display of colours. The source of their colours comes from the foods in their natural environment. The most important problem for the producers of these commercial species and aquaculturists is that most of these species lose their colours in the production process; therefore, consumer demand for them is low. The feed given to these species must provide the necessary ingredients for the species to acquire the desired colours. However, some producers use hormones and artificial colorants in order to attract consumers, increase their profit margin, and to make the fish they produce more vivid and shiny. Nevertheless, the colours acquired through such methods are not stable and the fish lose their colour after a while.

Fish colour is primarily dependent on the presence of chromatophores that contain coloured pigments. There are four main pigment groups that give colour to the skin and tissues of animals and plants, namely melanines, purines, pteridiums and carotenoids. Carotenoids, which dissolve in fat, give the skin the yellow and red colours. They also give the orange and green colours to the egg, skin and flesh of many fish (Fuji 1969). Carotenoids, which are produced primarily by phytoplankton and plants, are divided into two groups as carotens and xantofilles. Although

more than 600 carotenoids in nature have been defined, only a few of them are used in animal feeds, pharmaceuticals, cosmetics and food colouring (Bricaud et al. 1998; Ong and Tee 1992). //-carotene is a terpenoid pigment of increasing demand and a wide variety of market applications: as food colouring agent, as pro-vitamin A in food and animal feed, as an additive to cosmetics and multivitamin preparations and as a health food product under the antioxidant claim (Edge et al., 1997; Johnson and Schroeder, 1995).

Microalgae, which are important in the production of larval fish because of their nutritive ingredient, can be used as a natural pigment source in fish feeds. The use of microalgal biomass has been recently investigated with regard to its potential as a colouring agent (Gouveia et al. 1997; Raymundo et al. 2005). But the use of synthetic pigment sources is more common because they are easy to obtain (Sales and Janssens 2003). So, new research on the use of microalgae as fish feed must be done. The most important procedure for the natural production of -carotene is the culture of the unicellular biflagellate marine green microalga Dunaliella salina (Borowitzka, 1995). The extent of carotenoids accumulation in oil globules within the interthylakoid spaces of their chloroplast is directly proportional to the integral amount of light to which D. salina cells are exposed during a division cycle (Ben Amotz and Avron, 1983). Accumulation is enhanced under several conditions: high irradiance, stress temperatures, high salt concentration and/or nutrient deficiency (Ben-Amotz and Shaish, 1992). Under these conditions, up to 10% of the alga dry weight is -carotene (Ben-Amotz, 1999). Dunaliella -carotene occurs as a number of isomers, two of which, 9-cis and all-trans (in approximately equal amount), make up approximately 80% of the total (Borowitzka and Borowitzka, 1988). Superior bioavailability, antioxidant capacity and physiological effects, substantiate the commercial interest of the algal carotene over its synthetic counterpart (Becker, 1994; Ben-Amotz, 2009).

There is no study on the effect of natural and synthetic pigments on the colour of Angel fish . Therefore, this study was undertaken to determine the effect of pigment source on the skin colouring in Angel

fish (Pterophyllum scalare) using feeds containing Dunaliella salina as natural pigment source as well as astaxanthin as synthetic colorants.

Materials and methods

In this research, 200 larval Angel fish (Pterophyllum scalare), which were produced in aquarium at University of Tehran, Department of Natural Resources, were used. Their average living body weight was 0.62 ± 0.01 g, and average total length was 2.86 ± 1.12 cm. It was found that body of the fish has approximately no colour. Their sex was not taken into consideration. In the study, six aquariums, which had dimensions as 40 x 25 x 25 cm and working volume of 20 L, were used. There were 25 fishes in each aquarium. Two air pumps and one sponge filter were used in the aquariums for filtration and airflow. The aquariums were placed side by side in two lines. Since the experiment was done in summer, no heater was used.

The feed which was used in the research has been provided in the Fish Nutrition and Fish Feed Technology Laboratory at Department of Natural Resources, Faculty of Fisheries, and Department of Aquaculture. The feed was prepared with an attention to the nutritive needs of Angel fish . The feed used for the feeding of Angel fish included 43% crude protein (CP), 6% crude fat (CF), 2% crude cellulose (CC), 9.5% ash. So, only the pigment sources vary in the feed, which was prepared in three groups. While astaxanthin (Sigma) was added in the 1st group, and dried biomass of Dunaliella salina powder in the 2rd group; the 3th group was separated as the control group and no pigment material was added ito it. Dunaliella salina was grown in continuous mode in the plankton unit at Department of Natural Resources, Faculty of Fisheries and of Aquaculture. The total carotenoid amount was determined as 50 mg kg-1 in all groups of feed. A laboratory-type pellet machine was used in preparing feed. The fish were fed twice in the morning and afternoon ad libitum. While water temperature was measured everyday, pH values were measured in every 2 days for observing water parameters. The experiment was done twice for each group and lasted for 60 days.

Total carotenoid content of microalgae and synthetic colour material (astaxanthin) and change in the colour of fish were determined at the end of the experiment spectrophotometrically (Choubert and Storebakken 1989). After 10 mg of dry sample was passed through homogenisation process with the addition of 5 ml acetone (98%, Merck Germany), centrifuge procedure was applied for 10 min at 3,500 rpm. After that, these samples were read at 475 nm wavelength on the spectrophotometer. In order to determine the quantity of b carotene, calibration curve was used which was based on the absorbance values of 5 ml acetone solution which had 0.16, 1.63, 2.04, 3.27 and 4.09 mg g-1 of bcarotene values alternately. Assuming a complete of diet, we calculated the retention rate by the following equation (Ingle de la Mora et al. 2006); retention rate (%) = (mg of carotenoid of muscle) • (100)/ (mg of carotenoid in diet).

Statistical analysis consisted of one way ANOVA, using the probability level of 0.05 for rejection of the null hypothesis. After ANOVA, significant differences among means.

Results

Water temperature in all aquariums was measured daily, but pH values were measured once every 2 days throughout the experiment. The average water temperature was determined as 28.01 ± 0.5 °C, and pH as 7.9 ± 0.1.

The colouration areas in all the pigment materials were nearly the same. First, it was observed that it started from the ends of dorsal, anal and tail fins and then spread to abdomen. The spectrophotometer analysis was made for the colour change in the skin of the fish, which were fed on the feed that included different colorants, and the results are shown in the

Fig. 1.

At the beginning of this study, it was found that all fish colouration was 0.08 ± 0.01 mg g-1. In the study, colour changes appeared exactly in the same body parts (abdomen, fins, tail area and ventral lateral) in all the groups than the control group. However, it was determined that the fish fed on the feed that included astaxanthin had significantly colour with

0.31 ± 0.03 mg g-i (P<0.05). It was observed that the abdominal area, tail, dorsal and anal fins of the fish fed on the feed including D. salina, acquired a colour between pink and red (0.24 ± 0.01 mg g-1). It was also observed that the least colouration was found in the control group (0.09 ±

0.01 mg g-1).

Fig. 1. Carotenoid levels in Angel fish (Pterophyllum scalare) Skin after feeding on natural carotenoids from D. salina, synthetic pigment sources (astaxanthin) and a control diet. Bars represent means±s.d. Different letters over bars indicate significant difference (P<0.05).

As shown in Table 1, there were no significant differences between the groups of Angel fish fed experimental diets, in terms of survival rate

(P<0.05).

Growth parameters of the fish were shown in the Fig. 2. The maximum final body weight was found in fish of the second that were fed with D. salina (2.29 ± 0.32 g). However, the maximum total length was detected in the first group (Astaxanthin) of fish (4.37 ± 0.34 cm). In conclusion, there was no statistical difference among all groups in terms of both final body weight and final total length (P<0.05).

Table 1. survival of Angel fish (Pterophyllum scalare) after feeding on natural carotenoids from D. salina, synthetic pigment sources (astaxanthin) and a control diet for 60 days. Differences were not statistically significant (P > 0.05).

 

Groups

Survival rate (%)

1st (astaxanthin)

87і2.5

2nd (D. salina)

83.5і4

3rd (control)

85.5і5.5

Fig. 2 Growth parameters in Angel fish (Pterophyllum scalare) after feeding on natural carotenoids from D. salina, synthetic pigment sources (astaxanthin) and a control diet. Bars represent means±s■d■ there was no statistical difference among all groups in terms of both final body weight and final total length (P<0.05).

The main goal of the research was to determine the scale and duration of colour change in the fish with relation to pigment sources. So, nutritional change in the feed that included D. salina was ignored.

Discussion and conclusion

Carotenoids are known to have a positive role in the intermediary metabolism of fish (Segner et al. 1989). Colouration is controlled by the endocrine and nervous system, but dietary sources of pigment also play a role in determining the colour of fish. The effectiveness of carotenoid source in terms of deposition and pigmentation is species-specific. In addition, all fish species do not possess the same pathways for the metabolism of carotenoids, and therefore, there is no universal transformation of carotenoids in fish tissues (Chatzifotis et al. 2004).

Synthetic pigment materials brought about more accumulation in the tissue according to the results that were obtained regarding colour especially during the working period of astaxanthin and this influence is easily observed visually. The absorption and accumulation of astaxanthin in the fish is higher than the other carotenoids (Torrisen 1989). It was also observed that fish fed on feed, which included astaxanthin became more colourful than the other groups and their colour was red but D. salina gave pinkish-red colour. As a result, the 1st group of fish fed on feed including astaxanthin was significantly more colourful than the other groups. In the group that included P. cruentum less pigment accumulation occurred than in the 1st group. It seems necessary either to increase the amount of D. salina in the feed or to prolong the feeding time in order to have better results.

According to the results obtained from the experiment, it was observed that the Angel fish (Pterophyllum scalare) responded to colouration effected by the use either of synthetic or of natural pigment sources. This difference between two synthetic sources of pigment can be ascribed to the difference in quality, ingredients and accumulation period. Astaxanthin was efficiently utilized for deposition and coloration of the skin in red sea bream and Australian snapper (Lorenz 1998; Booth et al. 2004). Also, in gilthead sea bream synthetic astaxanthin and cantaxanthin or pigments from algae were efficiently absorbed (Gomes et al. 2002).

Although these two synthetic pigment sources have no cancerogenic effect and are permitted to be used in many countries, there is a search

for alternative colouring materials, because they are expensive and add about an extra 10-15% to the cost of feed. Microalga is one of the most favourite of these alternative materials both because its nutritive quality (its protein content ranges from 28% to 39%, the available carbohydrates vary between 40% and 57% and total lipids may reach 9 14 %) and its being a good source of carotenoid (Becker 1994).

D. salina that was used in this work is an alga, which contains /?-carotene, and the experiment tried to make use of this ingredient. It was observed that this alga, which was given together with the feed, has an important effect on the colour of the skin. However, the ratio of D. salina in the feed for the optimum coloration is the subject of another work. It is necessary to research the other variables that may be effective on the accumulation of pigments, such as the species of fish, the size of fish, colour types, and the duration of feeding on pigment sources.

References

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Ben-Amotz A (1999) Dunaliella P-carotene: from science to commerce. In: Seckbach J (Ed.), Enigmatic Microorganisms and Life in Extreme Environments. Kluwer Academic Publisher, The Netherlands, pp. 401-410.

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Becker E W (1994) Microalgae biotechnology and microbiology. Cambridge University Press, Cambridge.

Booth M, Warner-Smith R, Allan G and Glencross B (2004) Effects of dietary astaxanthin source and light manipulation on the skin colour of Australian snapper Pagrus auratus (Bloch and Schneider, 1801). Aquac Res 35:458-464.

Ben-Amotz A (1999) Dunaliella-carotene: from science to commerce. In: Seckbach, J. (Ed.), Enigmatic Microorganisms and Life in Extreme Environments. Kluwer Academic Publisher, The Netherlands, pp. 401-410.

Becker E W (1994) Microalgae: Biotechnology and Microbiology. Cambridge University Press, Cambridge, pp. 293.

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Chatzifotis S, Pavlidis M, Donate Jimeno C, Vardanis P, Divanach P (2004) The effect of carotenoid sources on skin coloration of red Porgy (Pagrus pagrus). Aquaculture Europe Conference, Biotechnology for Quality, Barcelona, Spain.

Choubert G, Storebakken T (1989) Dose response to astaxanthin and canthaxanthin pigmentation of rainbow trout fed various dietary carotenoids concentrations. Aquaculture 81:69-77.

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Gomes E, Dias J, Silva P, Valente L, Empis J, Gouveia JB, Young A (2002) Utilization of natural and synthetic sources of carotenoids in the skin pigmentation of gilthead sebream (Sparus aurata). Eur Food Res Technol 214:287-293.

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Growth performance of kutum (Rutilusfrisiikutum) larvae in relation to feeding duration with live food and artificial dry feed

Sedigheh mohammadzadeh1, Fatemeh Hasantabar2, Zeynab Abedi2

1guilan University, Rasht, Iran

2Sari Agricultural Sciences and Natural Resources University (SANRU), Sari, Iran Abstract

The aim of this study is to determine the effect of various periods of application of live food and artificial feed on growth and survival of kutum larvae. The experiment began on day 3 post- hatch (the onset of external feeding) and lasted for 21 days. for this experiment three experimental groups including Group A (only Artemia nauplii), Group B (mixed zooplankton), and Group C (21 days artificial feed) were considered. The mean body weight and total length of larvae fed mixed zooplankton (rotifers and copepod nauplii) were significantly higher (P<0.05) than those of the other treatments during rearing period. The lowest mean body weight and total length were found in larvae fed for 21 days with artificial feed. The highest survival rates were obtained in the groups of larvae fed during the whole period of rearing with Artemia nauplii (group A, 92.5%) or zooplankton (group B, 91.6%). Growth of kutum larvae increased proportionately with an increasing duration of feeding with zooplankton.

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