Evaluation of three species of tilapia, red tilapia and a ... - Science Direct

Aquaculture ELSEVIER

Aquaculture 138 (1995) 145-157

Evaluation of three species of tilapia, red tilapia and a hybrid tilapia as culture species in Saudi Arabia Abdul Qayyum Siddiqui *, Ahmed H. Al-Harbi Research Institute ofNatural Resources and Environment, P.O.Box 6086, Riyadh, Saudi Arabia Accepted 6 July 1995

Abstract The culture potential of three pure tilapia species, Oreochromis niloticus, 0. aureus, 0. mossambicus, hybrid tilapia (0. niloticus X 0. aureus) progeny and Taiwanese red tilapia (0. mossambicus X 0. niloticus) was evaluated in 10 m2 concrete tanks receiving freshwater. Tilapia were compared for growth, survival, yield, and feed conversion ratio. The different lines investigated showed different responses during different growing phases (fry, fingerling, sub-adult and adult). Final mean weights after 392 days rearing were higher for hybrid tilapia (327 g) than those of 0. niloticus (293 g), red tilapia (264 g) , 0. aureus (234 g) and 0. mossambicus ( 168 g). Yield ranged from 6.5 kg m - 3 (0. mossambicus) to 13.0 kg m- 3 (hybrid tilapia) and 2.2 to 4.4 kg l- ’ of water used, respectively. The feeding of tilapia up to satiation within 30 min twice daily gave very good feed conversion ratios; the overall average ranged from 1.24 (0. niloticus) to 1.63 (red tilapia). Survival after four growing phases was 80% (hybrid tilapia) , 74% (0. niloticus) , 72% (0. aureus), 61% ( 0. mossambicus) and 7% (red tilapia). Overall performance, based on fry, fingerling, sub-adult and adult rearing and the ranking based on final mean weight, specific growth rate, survival, and yield proved hybrid tilapia to be the best candidate for intensive tank culture, closely followed by 0. niloticus and 0. aureus. 0. mossambicus showed poor performance and red tilapia gave very low survival during the fry and larval rearing phases. Keywords: Tilapias; Tank culture; Growth; Yield

1. Introduction Tilapias have become Total annual production

one of the most important fish species for freshwater aquaculture. of tilapias and other cichlids from aquaculture in 1990 was 390

* Corresponding author 0044-8486/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDIOO44-8486(95)01088-2

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825 mt (FAO, 1992). Tilapia culture is mainly based on three species of the genus Oreochromis (0. niloticus, 0. aureus and 0. mossambicus) and two species of genus Tilapia (T. zillii and T. rendalli), though the number of culturable species used in aquaculture is quite large and Balarin and Haller ( 1979) have listed 23 species having aquaculture potential. Hybrids of Oreochromis including red tilapia have also been extensively used. Tilapia culture has become more popular because of the relative ease of culture in a variety of aquaculture systems and because of their favorable attributes as food fishes. Despite the popularity of tilapia culture, the overall production of market-size tilapia per hectare has remained relatively low because of the introduction of poor culturable species, mixed-sex culture and poor management. However, the introduction of better management practices (selection of more suitable species for culture, the use of all male or predominantly male fish population produced by hormone sex-reversal or hybridization, the use of protein rich diets, water quality management etc.) have led to improved tilapia production (Balarin and Haller, 1982; Liao and Chen, 1983; Wohlfarth and Hulata, 1983). Tilapia culture in Saudi Arabia has become a popular practice (Siddiqui and Al Najada, 1992) and is mainly based on a hybrid tilapia (0. niloticus X 0. aureus). 0. niloticus has been recently introduced and 0. spilurus (Vine, 1980) and 0. aureus (Siddiqui and Adam, 1985) have been used experimentally. As a number of tilapia species are entering in fish farming, it was considered desirable to make a detailed study on the comparative performance of three commercially important species of tilapia (0. niloticus, 0. aureus and 0. mossambicus), Taiwanese red tilapia and a hybrid tilapia with respect to growth and yield in separate concrete tanks where environmental conditions were almost similar. The main objective of this study was to find a tilapialine that would give good growth, food conversion and yield in tank culture with minimum water use.

2. Materials and methods The present study was conducted from 27 May 1992 to 28 June 1993 and included investigations on fry, fingerling, sub-adult and adult stages from the same spawn of five different lines of tilapia. 2.1. Tilapia species The fingerlings (2-3 g) of pure 0. niloticus, 0. aureus and 0. mossambicus were obtained in March 1989, from the Institute of Aquaculture, University of Stirling, where a Tilapiine reference collection is maintained (McAndrew and Majumdar, 1983). Fingerlings (5-10 g) of Taiwanese red tilapia (0. mossambicus X 0. niloticus) and Taiwanese strains of 0. niloticus and 0. aureus were imported in 1981 from Taiwan. The breeding of tilapias originating from Taiwan was initiated the same year and a hybrid stock from 0. niloticus and 0. aureus was produced in 1984. Since then Fl hybrid tilapia and red tilapia have been maintained as broodstocks by Fish Culture Project, KACST, at Dirab Fish Farm, 45 km from Riyadh.

A.Q.

2.2. Spawning andfry

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rearing

Three year old 0. niloticus, 0. aureus, red tilapia and hybrid tilapia with average weight of 600 g (females) and 850 g (males) were selected for spawning. Average weight of 0. mossambicus females and males were 350 g and 500 g, respectively. Twelve fish (nine females, three males) belonging to each species were stocked on 30 April 1992 in 10 m2 concrete tanks for spawning over a period of 21 days. During this period the fish were fed a 34% protein diet at the rate of 1.5% of total biomass daily in each tank. The water level in each tank was 40 cm. The tanks were aerated and about 25% of tank water was exchanged with freshwater daily. On 21 May 1992, the fry from each tank were harvested and transferred to five 900 1 aerated fiberglass tanks having a flow-through system. The fry were fed ad libitum (approximately 30% of body weight) for 7 days with a 51% protein eel larval feed with particle size ~250 microns. Three hundred fry of each species weighing 18-19 mg were obtained by screening the fry through 2.5 mm and 3.5 mm mesh screens to obtain the median size class. The remaining fry were reared in these tanks for later use. On 27 May 1992, 150 fry ( 18-19 mg) were transferred to 120 1 circular fiberglass tanks containing 30 1 water with a flow-through system providing a complete exchange of water every 6 h. The tanks were aerated, and each treatment was replicated twice. The fry were fed commercial tilapiapellets (PROVIMI Tilapia Starter Feed-crude protein 53%, crude fat 8.5%, crude fiber 1.5%, ash 11 .O%, NFT 15.0%, moisture 11 .O%, ME 3390 Kcal kg- ‘) which were sieved to produce 30&500 microns pellets to feed initially for 2 weeks and 500-700 microns pellets to feed for the remaining period. In the first week the feeding rate was 30% of total biomass in each tank, thereafter, it was reduced to 20, 20, 15, 15 and 10% of biomass in the following 5 respective weeks. Weekly feeding rate was adjusted after determining the group weight of 30-40 fry from each tank. The experiment was terminated on 8 July 1992 after 42 days rearing. All surviving fry in each tank were harvested, weighed in group and counted. About 40 fish from each tank were individually weighed. From this data average final weights, specific growth rates (SGR) , survival rates and feed conversion ratios were calculated. 2.3. Rearing ofjingerling The surviving fry of each species from the earlier experiment were mixed with its original fry stock and graded to obtain fish of uniform sizes (0.49-0.67 g) . Six hundred and thirty fish were stocked in one 10 m2 (3.8 m X 2.64 m X 1.2 m, water level 0.5 m) outdoor tank on 8 July 1992 and each species was assigned two tanks. The fish were fed 34% protein tilapia crumbles ( 1.0-l .5 mm) all they could eat in 30 min twice daily at 0800 and 1600 h, 6 days a week. The feed consumed during 12 days feeding was recorded and total biomass in each tank was determined every 2 weeks based on a group weight of 50-60 fishes. From this data the feed consumption rate (% body weight/day) was calculated. Left-over feed and excreta were removed by sweeping while draining the water. The water in each tank was almost completely exchanged with fresh water daily. The tanks were intensively aerated to maintain a dissolved oxygen level of about 4 mg l- ‘. After 112 days of rearing, all fishes from each tank were harvested, weighed in group and counted on 28 October, 1992. Fifty to 60 fish from each tank were randomly sampled,

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weighed individually and sexed. Thereafter, all fish were returned to their respective tanks. For the next two experiments the experimental tanks, experimental procedures, feed and feeding schedules and procedures’for collection of data were the same as described earlier. However,, the pellet size increased to 2.0-2.5 mm for the sub-adult fishes and 5.0 mm for the adults. 2.4. Rearing of sub-adult tilapia After the termination of the previous experiment fishes in each tank were hand graded to remove all small and some very large fishes. Three hundred graded fishes (average weight 28-30 g) from each tank were selected and re-stocked on 2 November 1992 and reared for 140 days terminating the experiment on 22 March 1993. 2.5. Rearing of adult tilapia Fishes from the earlier experiment were hand graded and 200 large-size fishes from each tank were selected and stocked in the same tank on 22 March 1993. No effort was made to make initial weight of the five species of tilapia uniform so that the real growth and yield potential of each species could be observed. The experiment was terminated on 28 June 1993 when the fishes had reached marketable size of > 200 g. 2.6. Analysis of data From the data collected after the termination of the last three experiments average final weights, specific growth rates (SGR (In W2 - In W 1) / (T2 - Tl ) X 100, where W 1 and W2 are mean fish body weights at times (d) when the first and second samples were taken (Tl and T2), and feed conversion ratios (kg dry feed fed/ kg wet weight gained) for each species were calculated. Effect of size-grading on sex-ratio was also determined. The data were subjected to the analysis of variance and Schaefer’s range test was used to determine the difference between treatment means using a Statgraphics Statistical Package (STSC, 1986). Observed sex ratios for each species were compared with an expected 1: 1 ratio using the chi-square test. Percentages data were transformed to arc sin values prior to analysis (Zar, 1984). Significance for all tests was 0.05. 2.7. Water quality analysis Water quality parameters were recorded in five tanks having different species of tilapia. Maximum and minimum temperatures were recorded daily. pH, dissolved oxygen (DO), ammonia nitrogen and alkalinity were recorded weekly. Total water hardness and salinity were determined every four weeks. All determinations were made between 07:OO and 07:30 h before the exchange of water using a HACH DR-2000 Water Analysis Unit, digital pH and oxygen meters and a salinity refractometer.

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Table 1 Mean body weight, specific growth rate (SGR), of tilapia

survival and feed conversion

Species

Initial weight

Final weight

SGR

Survival

(mg)

(mg)

(%)

(%)

18.5 a 19a 18.5 a 18 a 18 a

1155 ab 114Oab 958 b l137ab 1312 a

9.84 ab 9.16 ab 9.39 b 9.86 ab 10.20 a

80 85 75 21 86

0. niloticus 0. aWeUS 0. mossambicus Red tilapia Hybrid tilapia

Means with different letters in the same column are significantly

ratio (FCR) of fry of five species

FCR

ab a b c a

0.96 b 1.49a 1.32 ab 1.55a 1.28 ab

different (P < 0.05)

3. Results 3.1. Fry After 42 days of fry rearing hybrid tilapia reached the largest final mean weight and 0. mossambicus the lowest mean weight (Table 1) . Final mean weights of 0. niloticus, 0. aureus and red tilapia were not significantly different from each other. SGR also showed the same pattern among different tilapia as found for final mean weight. Maximum survival was found for hybrid tilapia (86%) and 0. aureus (85%) and the lowest for red tilapia (2 1%) (Table 1) . FCR ranged from 0.96 (0. niloticus) to 1.55 (red tilapia) . 3.2. Fingerlings Initial weights ranging between 0.49 to 0.67 g were not significantly different among different tilapias (Table 2). Final mean weights after 112 days rearing were not significantly different from each other (P > 0.05). Minimum SGR was recorded for 0. niloticus (3.13) and the maximum for hybrid tilapia (3.59)) but were not significantly different. Survival rate of red tilapia was poor (34%) and was significantly different from other tilapias (83Table 2 Mean body weight, specific growth fingerlings of five species of tilapia Species

0. niloticus 0. aureuS 0. mossambicus Red tilapia Hybrid tilapia

Initial weight

Final weight

(g)

(9)

0.67 0.65 0.58 0.49 0.50

a a a a a

rate (SGR),

22.66 a 22.5 1 a 22.5 1 a 24.00 a 28.05 a

survival,

SGR (%)

feed conversion

Survival (%)

ratio (FCR)

FCR

and feed intake of

Feed intake

Percentage of male

(%)’ 3.13 3.17 3.26 3.46 3.59

b ab ab ab a

94 a 91 a 83 a 34b 96 a

Means with different letters in the same column are significantly daily.

1.01 1.09 1.41 1.46 0.98 different

b b a a b

4.80a 4.89 a 5.05 a 5.61 a 5.33 a

35 49 51 39 53

(P < 0.05) * percentage

body weight

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Table 3 Mean body weight, specific growth rate (SGR), survival, feed conversion species of tilapia during winter months (November-March)

ratio (FCR) and feed intake of five

Species

FCR

0. niloticus 0. aureus 0. mossambicus Red tilapia Hybrid tilapia

Initial weight

Final weight

(8)

(g)

29.2 28.9 29.6 28.3 29.7

a a a a a

101.00 b 61.00 c 65.40 c 102.05 b 110.25 a

SGR

Survival

(%)

(%)

Feed intake

Percentage of male

(%) 0.88 0.53 0.56 0.91 0.93

a b b a a

99 a 96 b 100 a 99 a 98 ab

Means with different letters in the same column are significantly

15oc 2.20 a 1.90b 1.75b 1.70ab

1.78 b

1.46c 1.16d 1.88 a 1.79b

75 82 70 53 69

different (P< 0.05)

96%). The FCR for hybrid tilapia (0.98)) 0. niloticus not different from each other. However, significantly tilapia ( 1.46) and 0. mossambicus ( 1.41).

( 1.01) and 0. aureus ( 1.09) were higher FCR was recorded for red

3.3. Sub-adults Sub-adult tilapia (initial size range, 28.3-29.7 g) were reared during the winter period, November-March. Hybrid tilapia had the highest final mean weight and SGR (Table 3) and the poorest growth was recorded for 0. aureus and 0. mossambicus. Survival ranged from 100% (0. mossambicus) to 96.5% ( 0. aureus) . FCR were higher than those recorded in the previous two studies ranging from 1.50 (0. niloticus) to 2.20 (0. aureus). 3.4. Adult tilapia The initial weights of different tilapia were different from each other (Table 4). The largest final mean weight was recorded for hybrid tilapia and the lowest for 0. mossambicus. SGR were not significantly different among different tilapias except 0. aureus where the Table 4 Mean body weight, specific growth rate (SGR), survival, feed conversion ratio and feed intake of five species of tilapia. Means with different letters in the same column are significantly different (P < 0.05) Species

Initial weight

Final weight

(g)

(g)

0. niloticus

113.9b

293ab(179ab)”

0. au*ells 0. mossambicus Red tilapia Hybrid tilapia

68.3~ 234c(166ab) 11.2 c 168d(97c) 118.1 b 264bc(146b) 138.7 a 327 a (189 a)

aNet weight gain.“Net yield.

SGR

Survival

(%)

(%)

FCR

Feed intake

Percentage of male

Yield (kg m-‘)

11.7 ab (7.1 ab)b 9.1 c (6.4 ab) 6.5 d (3.8 c) 10.5 bc (5.8 b) 13.0 a (7.5 a)

(%) 0.96b

1OOa

1.25a 97a 0.88 b 98 a 0.82b 1OOa 0.88 b 99 a

1.50 b

1.69b

71

1.40b 1.75 a 1.75 a 1.55 ab

2.17a 1.75 b 1.65 b 1.68 b

82 87 69 66

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151

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50

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100

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150

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200

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Mean weight (g) Fig. 1, Daily feeding rates in relation to body weight of five different tilapia. Plotted points represent 2 weeks data for replicate tanks. -M-, 0. niloticus; n , 0. aureus; *, 0. mossambicus; -Cl-, Red tilapia; A, Hybrid tilapia.

maximum SGR was recorded. Survival rates were high (97-100%) and were not significantly different among different tilapia. 0. aureus gave the lowest FCR and red tilapia and 0. mossambicus the highest. Maximum net yield of 7.5 kg mP3 was recorded for hybrid tilapia and the minimum yield of 3.8 kg m-3 was obtained for 0. mossambicus. In terms of performance based on net final mean weight and net yield no difference was found among hybrid tilapia, 0. niloticus and 0. aureus. 0. mossambicus gave the lowest yield (Table 4). 3.5. Feed consumption The rate of feed consumption decreased with the increasing weight of fish (Fig. 1) , being 11.27% to 2.02% for fingerlings (average weight 0.49 - 23.36 g), 4.4% to 0.75% for subadults (average weight 28.9 - 102.0 g) and 1.8% to 1.6% for adults (average weight 68.3 - 276.4 g). Sub-adult fishes were reared during the winter period, therefore the rate of feeding was influenced by the decreasing water temperature. Nevertheless, as the winter of 1992-1993 was mild, daily mean feed consumption for all species ranged between 1.16% (0. mossambicus) and 1.88% (red tilapia) . Overall, feed consumption of different tilapias was not different during fingerling rearing (Table 2) and adult tilapia rearing (Table 4) with the exception of 0. aureus. However, during the sub-adult tilapia rearing conducted during the winter period, the lowest feed consumption was recorded for 0. mossambicus ( 1.16%) and the highest for red tilapia ( 1.88%).

152


Table 5 Overall range and mean water temperatures with different species of tilapia

138 (1995) 145-157

and some other water quality parameters

recorded in tanks stocked

Parameters

Range

Mean f s.d.

Max. temperature (“C) Min. temperature (“C) Dissolve oxygen (mg I-‘) NH,-N (mg 1-l)

21-32 10 - 21 3.8 - 6.2 0.14 - 0.44 1.1 - 8.3 160-216 840 - 1140 1.5

26*3 18*5 5.1 f0.8 0.25 +O.l s.1+0.1 202+11 996k 104 1.5

PH Alkalinity as CaC03 (mg 1-l) Total hardness (mg I- ’ CaCO,) Salinity (p.p.t.)

4. Discussion The effects of environmental factors on the performance of test tilapia species was minimized by providing similar environments to all species with respect to culture units, source of water, daily water exchange, uniform aeration, feed and feeding schedule and cleaning of the tanks. Water temperatures, pH, alkalinity, hardness and salinity were almost the same (Table 5). There was some variation in dissolved oxygen and ammonia levels, but the differences among different tanks having different tilapias were not significant. In ponds, particularly small ones, which differ considerably in the growth and yield potential (Wohlfarth and Moav, 1968; Buck et al., 1970) communal rearing of test fishes has been practiced (Dunham et al., 1982; Wohlfarth et al., 1983; McGinty, 1984; Wohlfarth and Moav, 1985). In the present study communal rearing was not practical as most of the culture units are small and the use of hapas (Eknath et al., 1993; Palada-de Vera and Eknath, 1993; Bolivar et al., 1993) is not possible and the clipping of fins on a large scale was avoided. The growth performance of F, hybrid tilapia was better in all growing phases than other tilapias (Table 1 and Table 2,3 and 4). However, in the final growing phase no significant difference was found in weight gain and yields (Table 4) of hybrid tilapia, 0. niloticus and 0. aureus. Generally, F, hybrids of 0. niloticus X 0. aureus have been found to show better growth than the parent species (Liao and Chen, 1983; Wohlfarth et al., 1983, Wohlfarth et al., 1990). Matricia et al, ( 1989) reported better growth for grey morph tilapia than the red tilapia in Indonesian pond culture. However, in a general review Pullin ( 1983) has ranked 0. aureus ahead to 0. niloticus, hybrid tilapia and red tilapia. Siddiqui and Adam ( 1985) found 0. niloticus showing better growth than 0. aureus in tank culture. Hulata et al. ( 1988) reported a large variation in growth rate among F, hybrids of 0. niloticus X 0. aureus from different farms in Israel, and in a later study Hulata et al. ( 1993) found Nile strains of 0. niloticus and 0. aureus as potential candidates for hybridization. Pure species of tilapia were obtained from the Institute of Aquaculture, Stirling, where a comparative study conducted by McAndrew and Majumdar (1989) on the growth of fingerlings of the same species showed that 0. aureus was the worst and 0. niloticus was the best and 0. mossambicus performed better than 0. aureus. In our study on the fingerlings no significant difference in the final mean weights was found, though lowest SGR was found for 0. niloticus and the highest for hybrid tilapia and this difference was mainly influenced by the starting initial weight of fishes (Table 2).


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138 (1995) 145-157

I

I

I

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AMJJASONDJFMAMJ 1992

Fig. 2. Monthly mean maximum

Months

and minimum air and water temperatures

1993

during the study period.

Sub-adult tilapia rearing coincided with the winter period (November-March). During this period the air and water temperatures dropped and the minimum water temperature of 10 “C was recorded for 3 days and 11 “C for 4 days, but not on consecutive days. Mean monthly maximum and minimum water temperatures ranged from 24 to 28 “C and 14 to 24 “C, respectively (Fig. 2). Growth of all tilapia species was affected during this period. The worst affected species were 0. aureus and 0. mossambicus (Table 3) and the least affected was hybrid tilapia. The temperature range for tilapia growth is reported to be 20-35°C (Balarin and Haller, 1982) with a optimum between 28 and 30°C. All three pure tilapia species investigated here are eurythermic (Philippart and Ruwet, 1982) and though 0. aureus is considered to be the most resistant to low temperature (Yashouv, 1960; Chervinski, 1982), it showed the poorest specific growth rate during the winter months (Table 3, Fig. 3). In the present study 0. aureus was a recently collected wild strain from Egypt (McAndrew and Majumdar, 1989), while 0. aureus of Israel has been under cultivation since 1960s and the two strains appear to be different in performance. Overall survival calculated as percentage of the percentage from fry to adult rearing for different tilapias were 80% (hybrid tilapia), 74% (0. niloticus), 72% (0. aureus), 61% (0. mossambicus) and 7% (red tilapia) . Survival rates during the fry rearing were significantly lower than (P < 0.05) the fingerling, sub-adult and adult rearing, but no difference in survival rates was found between these three subsequent rearing phases except in red tilapia. Heavy mortality was recorded for red tilapia during the fry (79%) and fingerling (66%) rearing, and appears to be related to genetic factors. Thereafter, the survival rates of

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138 (1995) 145-157

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200

250

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Fig. 3. Specific growth rates in relation to body weight of five different tilapia. Plotted points represent 2 weeks data for replicate tanks. Between two vertical lines are data for winter months. A, 0. niloticus; B, 0. aureus; C, 0. mossambicus; D, Red tilapia; E, Hybrid tilapia.

different tilapias were comparable. Behrends et al. ( 1982) also reported overall survival of 60% for red-gold tilapia (0. hornorum X 0. mossambicus) and the heavy mortality was correlated to inbreeding and genetic factors linked with red-gold coloration. The feeding of tilapias up to satiation within 30 min gave very good feed conversion for the entire 392 days culture period (0. niZoticus 1.24 + 0.3, hybrid tilapia 1.38 + 0.3, 0. aureus I.53 f 0.4, 0. mossambicus I .59 _+0.3, red tilapia 1.63 f 0.4) and these FCR values compare favorably with ratios of 1.5 to 2.0 reported for intensive freshwater tilapia culture in tanks (Balarin and Haller, 1979; Balarin and Haller, 1982; Lauenstein, 1978; Melard and

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138 (1995) 145-157

155

Table 6 Sex ratio (S) and mean weights (g) of males and females of different species of tilapia after size grading during the rearing period Species

0. niloticus 0. aweus 0. rnossurnbicus Red tilapia Hybrid tilapia

Fingerlings

Male Female Male Female Male Female Male Female Male Female

Sub-adults

%

weight

%

35 a 65 49.5 a 50.5 51 a 49 39 a 61 53.5 a 46.5

32.1 17.6 30.6 14.1 34.4 14.7 32.6 15.1 33.3 19.5

75.5 24.5 82.5 17.5 70.5 29.5 53b 47 69.5 30.5

Means with different letters in the same row are significantly

b b b

a

Adults weight

%

weight

118.4 65.1 68.4 53.2 70.0 26.3 114.1 74.6 108.8 80.5

71.5 b 28.5 82 b 18 87.5 c 12.5 69 c 31 66 a 34

328.9 161.5 257.0 157.0 172.3 72.9 285.5 196.2 376.1 242. I

different (P< 0.05)

Philippart, 1980), or even better than the FCR reported for 0. niloticus and 0. aureus (Siddiqui and Adam, 1985; Siddiqui et al., 1991a). Even during the winter period the feed conversion ratios were not high as compared to FCR values reported for different sizes of 0. niloticus (FCR 3.44.7) reared during the winter (Siddiqui and Howlader, 1991), where a fixed amount of ration was offered. No significant difference was found in the feeding rate of fingerlings of different lines, though the mean feeding rate varied from 4.8% (0. niloticus) to 5.6% (red tilapia). Similarly, feeding rates of adults were almost the same except 0. aureus which consumed more feed. However during the winter rearing of sub-adult tilapias, the feeding rates were found to vary among different lines. Caulton ( 1979) and Balarin and Haller ( 1982) have also reported variations in feeding rates among tilapia species. Tilapia males and females show divergent growth rates and males grow faster than females (Fryer and Iles, 1972; Lowe-McConnel, 1982). Therefore, if the slow growing females are removed by size-grading as soon as divergence of growth rates between sexes is recognized, a fish population with more males will be obtained, and this practice will lead to better growth and yield. In view of this background, the fishes were size graded and smaller fishes were removed. The results of size grading were apparent, and generally, the male percentage in the populations of different tilapias increased with the exception of hybrid tilapia where no significant change in the sex-ratio was noted (Table 6). Hybrid tilapia females showed rapid and better growth than females of other tilapia species, and therefore, the separation of males based on size was not significantly effected. Lauenstein (1978) and Balarin and Haller ( 1979) reported that after three gradings the upper 50% of the initial stock comprising fast growers was retained and the fish populations consisted of upto 70% males. The yields of 6.5 to 13.0 kg mu3 with 2.24.4 kg I-’ water used are low, and a higher production is possible if a flow through system is established and a flow rate of 0.5-1.0 1 mini’ kg- ’ biomass is maintained (Balarin and Haller, 1982; Siddiqui et al., 1991b). Among the five different tilapias tested, the growth and yield from the tank culture of hybrid

156


138 (1995)

145-157

tilapia was the highest and the present study indicates that hybrid tilapia is the best candidate for tank culture in Saudi Arabia.

Acknowledgements The authors wish to thank Hamad M. Al Hinty, Manager, Fish Culture Project, for his help and encouragements. We also thank Ahmed R. Al Najada, Wahab I. Sariul and Musa Chen Ta Chuan for technical assistance, and to Dr. Mohammad Nazir Khan for statistical analysis.

References Balarin, J.D. and Hailer, R.D., 1979. Tilapia. A Guide to Their biology and culture in Africa. University of Stirling, Scotland, pp. 174. Balarin, J.D. and Haller, R.D., 1982. The intensive culture of tilapia in tanks, raceways and cages. In: J.F. Muir and R.J. Roberts (Editors), Recent Advances in Aquaculture. Croom Helm, London, pp. 267-335. Behrends, R.B., Nelson, R.G., Smitherman, R.O. and Stone, N.M., 1982. Breeding and culture of the red-gold color phase of tilapia. .I. World Maricult. Sot., 13: 210-220. Bolivar, R.B., Eknath, A.E., Bolivar, H.L. and Abella, T.A., 1993. Growth and reproduction of individually tagged Nile tilapia (Oreochromis niloticus) of different strains. Aquaculture, 111: 159-169. Buck, D.H., Thoits, C.F. and Rose, C.R., 1970. Variation in carp production in replicate ponds. Trans. Am. Fish. sot., 99: 74-79. Caulton, M.S., 1979. The Biology and Farming of Tilapia in Southern Africa. Backhouse, Pietermaritzburg. Chervinski, J., 1982. Environmental physiology of tilapias. In: R.S.V. Pullin and R.H. Lowe-McConnel (Editors), The Biology and Culture of Tilapias. ICLARM Conf. Proc. 7, International Center for Living Resources Management, Manila, Philippines, pp. 119-128. Dunham, R.A., Smitherman, R.O., Chappel, J.A., Youngblood, P.N. and Bite, T.O., 1982. Communal stocking and multiple rearing technique for catfish genetic research. J. World Maricult. Sot., 13: 261-267. Eknath, A.E., Tayamen, M.M., Palada-de Vera, MS., Danting, J.C., Reyes, R.A., Dionisio, E., Capili, J.B., Bolivar, H., Abella, T.A.,Circa, A.V., Bentsen,H.B., Gjerde, B.,Gjedrem, T. and Pullin, R.S.V., 1993. Genetic improvement of farmed tilapias: the growth performance of eight strains of Oreochromis niloticus tested in different farm environments. Aquaculture, 111: 171-188. FAO 1992. Aquaculture Production, FAO Fisheries Circular No.815, Rev.4, Rome. Fryer, G. and Iles, T.D., 1972. Cichlid Fishes of the Great Lakes of Africa: Their Biology and Evolution. Oliver and Boyd, Edinburgh. Hulata, G., Wohlfarth, G.W. and Halevy, A., 1988. Comparative growth tests of Oreochromis niloticusX 0. nureus hybrids derived from different farms in Israel in polyculture. In: R.S.V. Pullin, T. Bhukasawan, K. Tonguthai and J.L. Maclaen (Editors), The Second International Symposium on Tilapia in Aquaculture. ICLARM Conf. Proc. 15, pp. 197-20 1. Hulata, G., Wohlfarth, G.W., Karplus, I., Shroeder, S.H., Halevy, A., Rothbard, S., Cohen, S., Israel, I. and Kavessa, M., 1993. Evaluation of Oreochromis niloticus X 0. mreus hybrid progeny of different geographical isolates reared under varying management regimes. Aquaculture, 115: 253-271. Lauenstein, P.C., 1978. Intensive culture of tilapia with geothermally heated water. In: R.O. Smitherman, W.L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes, Symp. Proc. Fish Culture Section, American Fisheries Sot., Auburn, AL, pp. 82-85. Liao, I.C. and Chen, T.P., 1983. Status and prospects of tilapia culture in Taiwan. Proceedings of the First International Symposium on Tilapia in Aquaculture. Tel Aviv University, pp. 588-598. Lowe-McConnel, R.H., 1982. Tilapias in fishcommunities. In: R.S.V. Pullin and R.H. Lowe-McConnel (Editors), The Biology and Culture of Tilapias. ICLARM Conf. Proc. 7, International Center for Living Resources Management, Manila, Philippines, pp. 88-l 13.


138 (1995) 145-157

157

Matricia, T., Talbot, A.J. and Doyle, R.W. 1989. Instantaneous growth rate of tilapia genotypes in undisturbed aquaculture systems. I. ‘Red’ and ‘Grey’ morphs. Aquaculture, 77: 295- 306. McAndrew, B.J. and Majumdar, K.C., 1983. Tiiapia stock identification using electrophoretic markers. Aquaculture, 30: 249-261. McAndrew, B.J. and Majumdar, K.C., 1989. Growth studies on juvenile tilapia using pure species, hormonetreated and nine interspecific hybrids. Aquacult. Fish. Manage., 20: 35-47. McGinty, A.S., 1984. Suitability of communal rearing for performance testing of tilapias. Proc. Carib. Food Crops Sot., 19: 259-266. Melard. Ch. and Philippart, J.C., 1980. Intensive culture of Surotherodon nibricus in Belgium. EIFAC Symposium on New Development in the Utilization of Heated Effluents and of Recirculation Systems for Intensive Aquaculture. EIFAC/80/Symp/Doc.E. II,20 pp. PaIada-de Vera, MS. and Eknath, A.E., 1993. Predictability of individual growth rates in tilapia. Aquaculture, 11I: 147-158. Philippart, J.C. and Ruwet, J.C., 1982. Ecology and distribution of tilapias. In: R.S.V. Pullin and R.H. McConnel (Editors), The Biology and Culture of Tilapias. ICLARM Conf. Proc. 7, International Center for Living Resources Management, Manila, Philippines. Pullin, R.S.V., 1983. Choice of tilapia species for aquaculture. Proceedings of the First International Symposium on tilapia in Aquaculture. Tel Aviv University, pp. 65-76. Siddiqui, A.Q. and Adam, A.A., 1985. Studies on comparative growth of Sarofherodon niloticus and Sarotherodon aureus in outdoor concrete tanks using drainage water. Saudi BioI. Sot.. 8: 333-343. Siddiqui, A.Q. and Howlader, MS., 1991. Growth of Nile tilapia, Oreochromis niloticus (L.) in response to winter feeding. J. Aqua. Trap., 6: 153-156. Siddiqui, A.Q., Howlader, M.S. and Adam, A.A., 1991a. Management strategies for intensive culture of Nile tilapia (Oreochromis nifoticus L.) in tanks using drainage water in Al Hassa region of Saudi Arabia. Arab Gulf J. Sci. Res., 9: 149-163. Siddiqui, A.Q., Howlader, M.S. and Adam, A.A., 1991b. Effects of water exchange on Oreochromis niloticus (L.) growth and water quality in outdoor concrete tanks. Aquaculture, 95: 67-74. Siddiqui, A.Q. and Al Najada, A.R., 1992. Aquaculture in Saudi Arabia. World Aquaculture, 23: 6-9. STSC, 1986. Statgraphics, Statistical Graphics Systems, Statistical Graphics Corporation, User’s Guide. Vine, P.J., 1980. Cultivation of fishes in the family Cichlidae in the Red Sea. In: Proceedings of the Symposium on the Coastal and Marine Environment of the Red Sea, Gulf of Aden and Tropical Indian Ocean. pp. 389399. The Red Sea and Gulf of Aden Environmental Programme, Jeddah (ALECSO). Wohlfarth, G.W. and Moav, R., 1968. The relative efficiency of experiments conducted in undivided ponds and ponds divided by nets. FAO Fish. Rep., 44: 487492. Wohlfarth, G., Hulata, G., Rothbard, S., Itzkowich, J. and Halevy, A., 1983. Comparisons between interspecific tilapia hybrids for some production traits. Proceedings of the First International Symposium on Tilapia in Aquaculture. Tel Aviv University, pp. 560-569. Wohlfarth, G.W. and Hulata, G., 1983. Applied genetics of tilapias. Second revised edition ICLARM Studies and Reviews 6,26 pp. Wohlfarth, G.W. and Moav, R., 1985. Communal testing, a method of testing the growth of different genetic groups of common carp in earthen ponds. Aquaculture, 48: 143-157. Wohlfarth, G.W., Hulata, G. and Halevy, A., 1990. Growth, survival and sex ratio of some tilapia species and interspecific hybrids. In: H. Rosenthal and S. Sarig (Editors), Research in Modem Aquaculture. European Aquaculture Society Special Publication 11, pp. 87-101. Yashouv, A., 1960. Effects of low temperature on Tilapi!piLc nilmica and Tilupia galilaea. Bamidgeh, 12: 62-66. Zar. J.H.. 1984. Biostatistical Analysis. Prentice Hall, Englewood Cliff, NJ.