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The manual rupture of the eggshell could rescue a disoriented larva. Allen (1991) reported that the body turnover in the later stage is an important process for larval hatching in demersal species. However, Kunz (2004) claimed that demersal eggs have the animal pole facing the free end, but we suspect that this author may have only observed the late stages of embryonic development. Olivotto et al. (2003) found that the embryo of Chrysiptera parasema could not hatch naturally if fish did not orient properly, since the proximal end of the egg was not easily bent. Recognition of the importance of body turnover in clownfish would help improve the hatching success in hatchery management. Given the

importance of egg orientation in embryo development, it would be a challenge to mass hatch clownfish in a conventional hatching jar if eggs could not attach to a specially designed substrate.

In summary, the time requirement for each major developmental stage from cleavage to hatching was documented in this study. The comparison of organogenesis between this and other clownfish species highlights the variation among closely related species in the Amphiprion genus. The developmental sequence of major organs such as internal ear, eyes, gills, digestive tract and fins provides an insight into understanding the possible interactions of clownfish with their environment. The process of pigment formation from the early embryo to later stages would contribute to a further understanding of the ontogeny of coloration in damselfish. The overall understanding of the embryology and ontogeny of A. ocellaris may help improve the culture of other coral reef fish.

Figure 1. The embryonic development of Amphiprion ocellaris, showing (A) 50% epiboly with arrow indicating the formation of the head and (B) the 70% epiboly with arrow indicating the formation of the eye bud. (C) The black mass (BM) was surrounded by numerous small (OGs) and medium (OGm) oil globules.

Iran-Larvi, ll-!2 December 2Ol2-Karaj

ABC

Figure 2. Embryonic development of Amphiprion ocellaris, showing somite formation with arrow indicating somites (A) and pigment cells (B) at the early formation and at the end of the epiboly (C).

А В с D

E F С H

Figure 3. Embryonic development of Amphiprion ocellaris at turnover stage, showing black mass (BM), black mass residuals (BMr), eye (E), oil globule (OG), melanophore in the body (Mb), migrate melanophore (Mm) and tail (T).

A B

c

Figure 4. Lateral views of the embryo 4 days old (A), 6 days old (B) and immediately after hatching (C), showing chorion (Ch), eye (E), heart (H), melanophore (M), myomeres (MY), oil globule (OG), otolith (O), pectoral fin (P), stalk (S), tail (T) and yolk sac (YS).

Figure 5. Post hatching larvae, showing the development of the caudal fins (A, C, E, F) and the development of body colour (B, D, G, H, I).

Agius, C. & Roberts, R.J., 2003. Melano-macrophage centres and their role in fish pathology. Journal of Fish Diseases, 26, 499-509.

Ahlstrom, E.H. & Moser, H.G., 1980. Characters useful in identification of pelagic marine fish eggs. California Cooperative Oceanic Fisheries Investigations Reports, 21, 121-131.

Allen, G.R., 1975. The anemonefishes, their classification and biology. Neptune City, New Jersey: T.F.H. Publications.

Allen, G.R., 1991. Damselfishes of the world. Germany: Hans A. Baensch.

Arezo, M.J., Pereiro, L. & Berois, N., 2005. Early development in the annual fish Cynolebias viarius. Journal of Fish Biology, 66, 1357-1370.

Arvedlund, M., Bundgaard, I. & Nielsen, L.E., 2000a. Host imprinting in anemonefishes—does it dictate spawning site preferences? Environmental Biology of Fishes, 58, 201-211.

Arvedlund, M., Larsen, K. & Windsor, H., 2000b. The embryonic development of the olfactory system in Amphiprion melanopus in relation to the anemonefish host imprinting hypothesis. Journal of the Marine Biological Association of the United Kingdom, 80, 1103-1109.

Arvedlund, M., McCormick, M.I. & Ainsworth, T., 2000c. Effects of photoperiod on growth of larvae and juveniles of the anemonefish Amphiprion melanopus. NAGA—The WorldFish Centre Quarterly, 23, 18-23.

Arvedlund, M., McCormick, M., Fautin, D.G. & Bilds0e, M., 1999. The anemonefish A. melanopus (Bleeker) (Pisces: Pomacentridae): a study of host detection and possible imprinting. Marine Ecology Progress Series, 188, 207-218.

Bagnara, J.T. & Hadley, M.E., 1973. Chromatophores and colour changes: the comparative physiology of animal pigmentation. London: Prentice Hall International.

Brooks, S., Tyler, C.R. & Sumpter, J.P., 1997. Egg quality in fish: what makes a good egg? Reviews in Fish Biology and Fisheries, 7, 387-416.

Buston, P.M., 2003. Mortality is associated with social rank in the clown anemonefish (Amphiprion percula). Marine Biology, 143, 811-815.

Chadwick, N.E. & Arvedlund, M., 2005. Abundance of giant sea anemones and patterns of association with anemonefish in the northern Red Sea. Journal of the Marine Biological Association of the United Kingdom, 85, 1287-1292.

Cronin, E.R. & Seymour, R.S., 2000. Respiration of the eggs of the giant cuttlefish Sepia apama. Marine Biology, 136, 863-870.

Dunn, D.F., 1981. The clownfish sea anemones: Stichodactylidae (Coelenterata: Actiniaria) and other sea anemones symbiotic with pomacentrid fishes. Transactions of the American Philosophical Society, 71, 1-115.

Elliott, J.K. & Mariscal, R.N., 2001. Coexistence of nine anemonefish species: differential host and habitat utilization, size and recruitment. Marine Biology, 138, 23-36.

Fautin, D.G., 1991. The anemonefish symbiosis: what is known and what is not. Symbiosis, 10, 23-46.

Fautin, D.G., 1992. Anemonefish recruitment: the roles of order and chance. Symbiosis, 14, 143-160.

Fautin, D.G. & Allen, G.R., 1997. Anemone fishes and their host sea anemones: a guide for aquarists and divers. Western Australian Museum.

Godwin, J., Luckenbach, J.A. & Borski, R.J., 2003. Ecology meets endocrinology: environmental sex determination in fishes. Evolution and Development, 5, 40-49.

Green, B.S., 2004. Embryogenesis and oxygen consumption in benthic egg clutches of a tropical clownfish, Amphiprion melanopus (Pomacentridae). Comparative Biochemistry and Physiology, 138A, 33.

Green, B.S. & McCormick, M.I., 2004. O2 replenishment to fish nests: males adjust brood care to ambient conditions and brood development. Behavioural Ecology, 16, 389-397.

Hattori, A., 1994. Inter-group movement and mate acquisition tactics of the protandrous anemonefish, Amphiprion clarkii, on a coral reef, Okinawa. Japanese Journal of Ichthyology, 41, 159-165.

Hobbs, J.P.A., Munday, P.L. & Jones, G.P., 2004. Social induction of maturation and sex determination in a coral reef fish. Proceedings of the Royal Society B, 271, 2109-2114.

Hoff, F.H., 1996. Conditioning, spawning and rearing of fish with emphasis on marine clownfish. Dade City, FL: Aquaculture Consultants, Inc.

Holbrook, S.J. & Schmitt, R.J., 2005. Growth, reproduction and survival of a tropical sea anemone (Actinaria): benefits of hosting anemonefish. Coral Reefs, 24, 67-73.

Johnston, G., Kaiser, H., Hecht, T. & Oellermann, L., 2003. Effect of ration size and feeding frequency on growth, size distribution and survival of juvenile clownfish, Amphiprion percula. Journal of Applied Ichthyology, 19, 40-43.

Kunz, Y.W., 2004. Developmental biology of teleost fishes. Netherlands: Springer.

Liew, H.J., Ambak, M.A. & Abol-Munafi, A.B., 2006. Embryonic development of clownfish Amphiprion ocellaris under laboratory conditions. Journal of Sustainability and Management, 1, 64-73.

Long, W.L. & Ballard, W.W., 2001. Normal embryonic stages of the Longnose Gar, Lepisosteus osseus. BMC Developmental Biology, 1, 6.

Matarese, A.C. & Sandknop, E.M., 1984. Identification of fish eggs. In Ontogeny and systematics of fishes. La Jolla, California: American Society of Ichthyologists and Herpetologists.

Olivotto, I., Cardinali, M., Barbaresi, L., Maradonna, F. & Carnaveli, O., 2003. Coral reef fish breeding: the secrets of each species. Aquaculture, 224, 69-78.

Patterson, R.H. & Martin-Robichaud, D.J., 1983. Embryo movements of Atlantic salmon (Salmo salar) as influenced by pH, temperature, and state of development. Canadian Journal of Fisheries and Aquatic Sciences, 40, 777-782.

Porat, D. & Chadwick-Furman, N.E., 2004. Effects of anemonefish on giant sea anemones: expansion behaviour, growth and survival. Hydrobiologia, 530/531, 513-520.

Stearns, M.E. & Wang, M., 1987. Evidence for intermediate filaments in squirrelfish erythrophores of Holocentrus ascensionus (Rufus). Experimental Cell Research, 173, 395.

Wabnitz, C., Taylor, M., Green, E. & Razak, T., 2003. From ocean to aquarium.

Cambridge, UK: UNEP-WCMC.

Yasir, I., Qin, J.G., 2007. Embryology and early ontogeny of an anemonefish Amphiprion ocellaris. Journal of Marine Biology, 87, 1025-1033.

The impact of different levels of Betaine supplementation and diet on pikeperch (Sander lucioperca) larviculture

Mahmood Azimirad*1, Mehrdad Farhangi2, Bagher Mojazi Amiri2, Iraj Effatpanah komaee3, Hadis Mansouri Taee4, Hamid Reza Ahmadnia5

1 Department of Fisheries, Faculty of Natural Resources, University of Urmia, Urmia, Iran

2 Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karadj, Iran

3 Center of Renewing Fish Resource Yosefpoor, Siahkal, Iran.

4 Department of Fisheries, Faculty of Natural Resources, University of Sari, Sari, Iran

5 Department of Fisheries, Faculty of Natural Resources, University of Gorgan, Gorgan, Iran

Abstract

The aim of current study was to determine the effects of different levels of Betaine on growth performance, feeding efficiency and survival rate of Sander lucioperca larvae. The larvae (initial weight 1.52+0.06 mg) were weaned from day 12 post hatching (dph) with one of the six treatment which was commercial trout starter diet (Bio Optimal) and different levels of Betaine supplementation (0.5, 1, 1.5, 2 and 2.5%) as well as a treatment that was feeding with live food (Artemia nauplii) as control group. Trial lasted for 4 weeks (until 40 dph). The best final weight, specific growth rate, final length and condition factor was obtained in control group (P<0.05). Different levels of Betaine supplementation had no significant effects on growth performance. Feed conversion ratio showed no significant difference between treatments, however food efficiency ratio was significantly higher in control group (P<0.05). The highest survival rate and cannibalism was observed in control group while larvae fed artificial diet (i.e Bio Optimal and different levels of Betaine supplementation) had 100% mortality after 33 dph. Results indicated that Betaine supplementation did not improve growth and survival rate of S. lucioperca, and further studies regards weaning of pikeperch larvae are needed. Keywords: Betaine; Pikeperch; Growth; Feed efficiency; Survival; Cannibalism

Pikeperch, Sander lucioperca (previously named Stizostedion lucioperca) is a valuable species for aquaculture due to its rapid growth, flesh quality and high commercial value (Hamza et al., 2008). This species, had been introduced into water reservoirs in several European countries (among others the Netherland, Turkey, France, Italy, Spain) (Larsen and Berg, 2008) and North African countries (for example: Tunisia) (Hamza et al., 2007). Pike perch is found in freshwater and brackish water in the Caspian watershed (Ural, Volga, Kura and Sefid Roud rivers) and in the basins of the Black, Azov, Aral, and Baltic Sea (Craig, 2000). In Europe, production of pikeperch fingerlings depends mainly on extensive and semi-intensive pond culture (Hilge and Steffens, 1996). In spite of the small size and fragility of percid larvae which have limited the development of percid culture (Kestemont and Melard, 2000), a growing interest in the development of pikeperch intensive rearing has developed in several countries (Ostaszewska et al., 2005; Hamza et al., 2007; Kestemont et al., 2007).

Development of artificial food for pikeperch larviculture is currently available for the last decade and there are few published nutritional requirement for it. Practical diets fed to pikeperch larvae are usually formulated based on the nutrition requirements of salmons or freshwater fishes (Brown and Barrows, 2002). Using these diets (starter food trout), has led to significant fluctuation in survival and growth in pikeperch larvae (Kestemont and Melard, 2000). It is clear that visual and chemical sense play crucial rules in pikeperch larvae for weaning live food to artificial food (Halver and Hardy, 2002). Thus the failure of feeding exclusively artificial food can be related to the inability of larvae to recognize or locate feed granules and ingest those (Xu et al., 2003).

Some chemical compounds have been used to stimulate the feed intake, decrease feed waste and prevent the deterioration of water quality. These attractant substances help to improve dietary intake, promote quicker food intake, minimize the feed remaining time in water and thereby the nutrient leaching decreases, provide additional nutrients for protein and energy

metabolism simultaneously. Behavioral studies demonstrated that Betaine ((CH3)3N+-CH2COO-) and some water-soluble amino acids (like L-amino acids) have a potential role for stimulation of food intake and act as chemical cues for pikeperch larvae. Betaine is highly soluble substance and spread rapidly in water when feeds are wetted (Yilmaz, 2005). The aim of current study was to investigate the effects of different levels of dietary supplemented with Betaine on growth, feeding efficiency and survival rate of pikeperch larvae.

Materials and methods

Fish origin and experiment preparations

The larvae used (12 dph) were the offspring of one batch of eggs from semi artificial spawning without hormonal injection (Kucharczyk et al., 2007) wild females and males caught in the spawning season (lately winter season) in Aras dam, Urmia, Iran. The brood stocks were transported to the Center of Renewing Fish Resource Yosefpoor, Siahkal, Iran. The spawning nests with eggs were transported to the hatchery and placed in special circulated incubation tanks (1000 l) at 7.7 oC until hatching (approximately 80 0C days) (Steffens et al., 1996). Eleven days after hatching 46000 larvae were counted (volumetrically) and stocked into rearing tanks. 23 circulated tanks (1.8x1.8x0.5) were stocked with the density of 10 larvae l-1. Larvae were stocked into rearing tanks with working volumes of 0.2 m3. Seven treatments in triplicates were randomly assigned to the tanks. A 12:12 h light regime was provided by fluorescent tubes (120 lux) giving a moderate light intensity at the water surface (Hamza et al., 2007). The flow rate in each tank was approximately 0.5-1 L min-1 with a slight aeration. Tanks were cleaned by siphoning once a day to remove the unconsumed food, fish waste and dead larvae (Kestemont et al., 2007).

The larvae were kept in outdoor flow-through water tanks supplied by filtered pond water (filter size = 50 u). Temperature and dissolved O2, controlled daily, maintained at 19-21°C and above 6 mg L-1, respectively. pH was determined twice a week and observed at level 7-8

 (Szkudlarek and Zakes, 2007).

Experimental procedure

From the beginning of exogenous feeding (6 dph), larvae were fed a mixture of sieved zooplankton (mainly rotifers) collected from ponds and Artemia nauplii (Inve, Thailand) before transport from the private hatchery to the experimental station. From 7-11 dph onward, amount of zooplankton decreased and Artemia increased in feeding regime. The experimental treatments were initiated with larvae 12 dph. Twenty one groups of 2000 larvae were randomly divided into the larval rearing tanks to provide a triplicate of five levels of Betaine supplementation treatments (0.5, 1, 1.5, 2 and 2.5%) and a commercial trout starter diet group (Bio Optimal) as well as a live food treatment (control group). All groups of larvae were fed Artemia nauplii (300-350 u) accompaniment of de capsulated cyst (150-200 u) and dense was approximately targeted 1000­1500 naupli l-1. (Ostazewska et al., 2005). The weaning procedure consisted of decreasing the proportion of Artemia nauplii while increasing the proportion of dry feed (Artemia nauplii : dry feed in a ratio of 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100%) within 6 consecutive days. The weaning period of larvae were completed on 17 dph. Control group fed live food at 4 h interval throughout the day from 8 am to 8 pm manually, and all groups of larvae fed commercial diets (Bio Optimal+Bio Optimal with different levels of Betaine supplementation) were fed at 2 h interval throughout the day from 8 am to 8 pm manually, 7 days a week. Feeding levels were fixed at 0.3-0.5 g tank-1 day-1 for commercial diets, and approximately 500-600 Artemia nauplii fish-1 day-1 was targeted for the control group (Kestemont et al., 2007). The commercial diet Bio Optimal (0.2 mm) was used for weaning and was distribute to the end of the experiment (Table 1). Artemia nauplii (INVE) were replaced by newly hatched Artemia nauplii (Urmia), from day 24 to 27 post of hatching (Bodis et al., 2007). Different levels of Betaine supplementation were prepared by dissolving 0.5, 1, 1.5, 2, 2.5 g of each in 50 ml distilled water and spraying on 100 g Bio Optimal (Yilmaz, 2005).

Research procedures and statistical analysis

At the beginning of the experiment, 50 larvae and at the end of experiment, all larvae were weighed and checked individually for the normality and deformation under microscope. Fish measurements were taken every seven days by means of micrometer to determine growth rates, fish condition factor, the feeding coefficients of the feed, and the daily feed ration. Samples of 50 fish were chosen at random from each tank and their body weights (± 0.001 g) and total length (± 0.01 mm) were measured. To estimate the number of larvae which ingested the feed, in the first 2 days of co-feeding, 10 larvae per tank were collected in a glass becher to observe the presence (or not) of the commercial diet in digestive tract (Hamza et al., 2008).

The data collected was used to calculate the values of the following rearing indexes:

• Condition factor, CF = 100x(body weight (mg)xbody length SL-3 (mm));

• Specific growth rate, SGR (% day-1)=100x(ln final body weight (mg)-ln initial body weight (mg))xrearing period-1 (days);

• Feed conversion ratio, FCR = weight of feed consumed (mg)x(final stock biomass (mg)-initial stock biomass (mg))-1;

• Feed efficiency, FE = (final stock biomass (mg) - initial stock biomass (mg))xweight of feed consumed (mg) -1;

• Survival rate, S (%) =100x(final abundance (individuals)xinitial abundance-1 (individuals));

• Cannibalism (%)=100 x (number of dead fish due to cannibalism (individuals)+ number of missing fish at the counting (individuals))xinitial abundance-1 (individuals))

Results are given as mean values and standard deviations. Value of, SGR, CF, Survival, Cannibalism were arcsin transformed. Statistical analysis was based on one-way Analysis of Variance (ANOVA). Significant differences between groups were estimated using a post-hoc Tukey's post-hoc test (HSD) with a significance level at P<0.05.

Analyses were performed using SPSS for Windows (Standard Version 13 SPSS Inc. Tulsa. OK, USA).

Table 1: Proximate composition of the experimental diet

Chemical composition (%DM)

Bio Optimal

0.5% Betaine

1% Betaine

1.5% Betaine

2% Betaine

2.5% Betaine

Crude protein

63.0

63.0

63.0

63.0

63.0

63.0

Crude lipid

11.0

11.0

11.0

11.0

11.0

11.0

Crude carbohydrate

8.6

8.6

8.6

8.6

8.6

8.6

Fiber

0.4

0.4

0.4

0.4

0.4

0.4

Ash

12.0

12.0

12.0

12.0

12.0

12.0

Total phosphorus

2.0

2.0

2.0

2.0

2.0

2.0

Gross energy (MJ/kcal)

20.8/4969

20.8/4969

20.8/4969

20.8/4969

20.8/4969

20.8/4969

Digestion energy (MJ/kcal)

18.9/4515

18.9/4515

18.9/4515

18.9/4515

18.9/4515

18.9/4515

Results

Effects of different levels of Betaine supplementation on growth performance of pikeperch larvae are presented in Table 2. The Average of larvae initial weight at the beginning of the experiment (12 dph) was 1.52+0.06 (mg) and no significant differences were observed between treatments. In 33 dph the larvae fed live food showed the higher weight than the treatments fed of Bio Optimal and different levels of Betaine supplementation (p<0.05). Larval average weight in 33dph was 46.16+17.55 (mg) in live food treatment, 2.79+0.46 in 0.5% Betaine and there was no significant difference between Bio Optimal and other levels of Betaine supplementation. SGR in 33 dph was 15.56+2.42 percent per day in live food treatment and 2.54 + 0.84 in 0.5% Betaine supplementation. Average length of the larvae fed live food at 33 dph was higher than other treatments (p<0.05). Unlike the initial length, no significant difference was observed between the initial CF of larvae in different treatments. Results showed that the larval final CF in live food treatment was significantly higher than the others (P<0.05).

Table 2: Growth factor of pikeperch larvae under different treatments (mean + SD)

Live food Bio Optimal       0/5%Betaine        1%Betaine        1/5%>Betaine 2%Betaine

(n=3)

*Values with different letters in the * Survival rate related to 33 dph

same line are significantly different (P<0.05)

Initial weight (mg)

1.49 ± 0.21a

1.52 ± 0.24a

1.62 ± 0.12 a

1.48 ± 0.46a

1.44 ± 0.53a

1.60 ± 0.15a

1.52 ± 0.92a

Final weight (mg)

46.16 ± 17.55a

3.56 ± 0.30b

2.79 ± 0.46b

3.36 ± 0.73b

2.08 ± 0.85b

4.24 ± 1.99b

3.73 ± 0.79b

Initial length (mm)

6.21 ± 0.33c

6.22 ± 0.44c

6.53 ± 0.28a

6.20 ± 0.38c

6.43 ± 0.23a

6.28 ± 0.50bc

6.41 ± 0.29ab

Final length (mm)

15.9 ± 2.30a

8.18 ± 0.60b

7.88 ± 0.58b

7.96 ± 0.73b

7.96 ± 1.06b

8.17 ± 1.13b

7.96 ± 0.83b

Initial CF

0.63 ± 0.16a

0.63 ± 0.10a

0.58 ± 0.03a

0.62 ± 0.05a

0.55 ± 0.02a

0.65 ± 0.09a

0/58 ± 0.04a

Final CF

1.02 ± 0.26a

0.65 ± 0.03b

0.57 ± 0.49b

0.67 ± 0.14ab

0.64 ± 0.32b

0.74 ± 0.16ab

0.73 ± 0.81ab

SGR (% day-1)

15.65 ± 2.42a

4.10 ± 0.90b

2.54 ± 0.84b

3.83 ± 1.23b

3.96 ± 0.37b

4.33 ± 2.32b

4.21 ± 1.17b

FCR

0.44 ± 0.2b

8.07 ± 2.35ab

16.32 ± 6.52a

9.62 ± 5.11ab

8.19 ± 1.09ab

9.06 ± 5.14ab

7.94 ± 2.78ab

FE

2.69 ± 1.53a

0.13 ± 0.04b

0.07 ± 0.03b

0.12 ± 0.06b

0.12 ± 0.15b

0.16 ± 0.14b

0.14 ± 0.61b

Survival (%)*

17.71 ± 4.29a

4.68 ± 1.45b

6.43 ± 1.25b

7.74 ± 2.60b

7.24 ± 1.06b

5.79 ± 1.87b

8.58 ± 1.95b

Cannibalism (%)

1.44 ± 0.59a

0.05 ± 0.87b

0.05 ± 0.05b

0.15 ± 0.14b

0.21 ± 0.11b

0.29 ± 0.46b

0.14 ± 0.12b

Specific growth rate trend in different treatments are shown in Fig 1. In 33 dph specific growth rate in pikeperch larvae fed Bio Optimal and different levels of Betaine supplementation was significantly more than the previous weeks (P<0.05). Specific growth rate of live food treatment was significantly higher in 26 dph to the end of the experiment (P<0.05).

2/5%Betaine

Fig. 1: Specific growth rate of pikeperch larvae under different treatments. Time is expressed in day's post of hatching (dph).

Different levels of Betaine supplementation had no significant effects on feed efficiency of pikeperch larvae. FCR was lower in live food treatment compare to Bio Optimal and different levels of Betaine supplementation but the difference was not significant. Feed efficiency ratio in live food treatment was significantly higher than the treatments fed Bio Optimal and different levels of Betaine supplementation (P<0.05).

The highest survival rate (17.17%) was observed in treatment fed live food (P<0.05). While the survival rate in Bio Optimal treatments and different levels of Betaine supplementation was lower than 10% and no significant difference were observed between treatments. The survival rate changing trends showed that the most larval mortality occurred in 12-24 dph. The mortality rate for was 93.44 and 66.68 % for Bio Optimal and live food respectively in 12-24 dph (Fig. 2). Pikeperch larvae fed live food showed the higher cannibalism than the treatments fed of Bio Optimal and different levels of Betaine supplementation (p<0.05).

Time (dph)

L2 26 33 40

 

 

a

a

a

a

a

a

a

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a

h b b b b b

#0ft

 

f

 

 

t......

1234567        1234567 1234567 1234567

1: Live food; 2: Bio Optimal: 3: 0.5% Betaine; 4: 1% Betaine; 5: 1.5% Betaine; 6: 2% Betaine; 7. 2.5% Betaine

Fig. 2: Survival rate of pikeperch larvae under different treatments.

Studies on the early life development of percid fish have shown that the transition of the larvae of pikeperch to exogenous feeding is a decisive event in the early stage of development, because failure to accomplish first feeding results in mortality (Kestemont et al., 2007). Betaine (glycin Betaine, trimethylglycin) is widely distributed in fish food organisms. The gustatory system of many fish species is highly sensitive to this substance. Betaine was used as a feed attractant and growth promoter for fish and crustaceans. It is reported that Betaine can enhance the growth performance in aquaculture (Kasumyan and Doving, 2003; Genc et al., 2006). In spite of information provided in other fish species, no research was found about using attractants in larval and juvenile of pikeperch. Therefore, the increasing research for using attractants in larval food is one of the key to the further development of pikeperch intensive larviculture.

According to these results supplementation of trout starter diet with Betaine had no significant effects on growth performance. Larvae fed live food had significantly higher final weight, growth, SGR, final length and CF compare to the treatments fed commercial trout starter diet and different levels of Betaine supplementation (0.5, 1, 1.5, 2, 2.5%). The highest final weight (93.94± 17.26), specific growth rate (16.52± 3.8 % daily-1) and final length (22.81± 1.48) found in the groups of larvae fed live food from beginning to end of the experiment and difference between treatments was significant (P<0.05). Yilmaz (2005) reported that DL-alanine and Betaine supplementation in commercial trout starter diet had no attracting role in the pre-larval stage of the African catfish, Clarias gariepinus (9 dph); however, in the post-larval stage, they had a very strong effect on the survival and growth rate. On the other hand, wet feeds were very effective and especially fresh water mussel (Unio terminalis) and combination of tubifex, chicken egg yolk and minced mussel gave significantly high growth rates. However, a recent paper (Sadeghi, 2004) demonstrated that the addition of Betaine supplementation  to  rainbow  trout larvae  diet increased growth

performance. Genc et al. (2006) reported that Betaine supplementation decreased final weights in both fresh and sea water conditions for blue tilapia (Oreochromis aureus). Final weight of fish fed the control diet (0% Betaine) showed better growth performance compared to fish fed 1

and 2 % Betaine (P<0.05).

Results suggested that Betaine supplementation enhanced growth performance in juvenile fish. It is evident that weaning size or age is directly related to the ontogeny of the species and to the development of the digestive system of the larvae. Therefore, the determination of optimum weaning age of pike perch larvae is the key to development of chemical receptors in larvae feeding (Kasumyan and Doving, 2003). Also results suggested that effect of Betaine supplementation may be different in any species (El-Husseiny et al., 2008). It is clearly that visual and chemical sense played crucial rules in pikeperch larvae for weaning to artificial food (Halver and Hardy, 2002). The failure of feeding exclusively formulated feed can thus be related to the inability of larvae to recognize feed granules as food or locate and ingest them (Xu et al., 2003). Considering to rudimentary information in chemical sense developing in pikeperch larvae was be mentioned, determination of optimum consume time of attractive material is not clear and using in shortly period of larvae may had no effects on growth performance (Ostazewska, 2005).

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