The complete mitochondrial genome of the hybrid grouper Epinephelus moara(♀)×Epinephelus tukula(♂), and phylogenetic analysis in subfamily Epinephelinae

The mitochondrial genome(mitogenome)of hybrid grouper Epinephelus moara(♀)×Epinephelus tukula(♂),a new hybrid progeny,can provide valuable information for analyzing phylogeny and molecular evolution.In this study,the mitogenome was analyzed using PCR amplification and sequenced,then the phylogenetic relationship of E.moara(♀)×E.tukula(♂)and 35 other species were constructed using Maximum Likelihood and NeighborJoining methods with the nucleotide sequences of 13 conserved protein-coding genes(PCGs).The complete mitogenome of E.moara(♀)×E.tukula(♂)was 16695 bp in length,which contained 13 PCGs,2 rRNA genes,22 tRNA genes,a replication origin and a control region.The composition and order of these genes were consistent with most other vertebrates.Of the 13 PCGs,12 PCGs were encoded on the heavy strand,and ND6 was encoded on the light strand.The mitogenome of the E.moara(♀)×E.tukula(♂)had a higher AT nucleotide content,a positive AT-skew and a negative GC-skew.All protein initiation codons were ATG,except for COX and ND4(GTG),ATP6(CTG),and ND3(ATA).ND2,COXII,ND3,ND4 and Cytb had T as the terminating codon,COXIII’s termination codon was TA,and the remaining PCGs of that were TAA.All tRNA genes,except for the lacking DHU-arm of tRNASer(AGN),were predicted to form a typical cloverleaf secondary structure.In addition,sequence similarity analysis(99%identity)and phylogenetic analysis(100%bootstrap value)indicated that the mitochondrial genome was maternally inherited.This study provides mitogenome data for studying genetic,phylogenetic relationships and breeding of grouper.

芳香化酶抑制剂letrozole对赤点石斑鱼(Epinephelus akaara)性逆转的作用

在繁殖季节,采用腹部埋植方式,用非类固醇型芳香化酶抑制剂(aromataseinhibitor,AI)letrozole以5mg/kg体重的剂量处理2龄雌性赤点石斑鱼(每4周埋植1次,共埋植2次),检查埋植后性腺组织结构、血清性类固醇激素以及脑和性腺芳香化酶活性的变化。结果显示:一次埋植AI即可有效诱导雌性赤点石斑鱼发生不同程度的性逆转;性腺成熟指数明显下降;性腺中卵细胞退化,精原细胞增殖,出现大量精母细胞和精子细胞;性逆转雄鱼的精巢在组织结构上与正常雄鱼精巢没有明显差异,部分鱼成为功能性雄鱼。第一次埋植AI后4周轻微挤压腹部有14.3%的鱼可排精,精子活力与正常雄鱼相同。第二次埋植后明显提高性逆转效果,排精率在第6、8周分别达到35.3%和48.4%。此外,埋植AI后性腺芳香化酶活性显著降低,但脑部芳香化酶活性的变化不明显;血清11-酮基睾酮(11-ketotestosterone,11-KT)浓度显著增加,雌二醇(estradiol-17β,E2)水平显著降低,而睾酮(testosterone,T)含量无明显变化。这些结果表明,AI主要通过抑制内源性E2的产生并提高11-KT水平,从而诱导赤点石斑鱼由雌性转变为雄性。

A Preliminary Study on Fertilization Biology between Epinephelus coioides(♀) and Epinephelus lanceolatus(♂)

Crossbreeding between Epinephelas coioides （ ♀ ） and Epinephelus lanceolatus （♂） was conducted by artificial insemination. Fertilized eggs were col- lected at 0, 30, 90 s, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 min post-insemination respectively, which were fixed by Smith＇s solution, embedded by paraffins and stained by H.E. According to the characteristics of Epinephelus coioides eggs, tissue section method was modified. The results showed that the sperms of Epinephelus lanceolatus rapidly entered the eggs of Epinephelus coioides at 30 s - 1 rain post-insemination. Observation results of tissue sections showed that mature eggs of Epinephelus coioides remained at metaphase of secondary maturation division. The eggs were activated after sperm penetration into the egg. With the develop- ment of secondary maturation division, at 2 rain post-insemination, eggs reached the metaphase of secondary maturation division ; at 3 - 6 rain post-insemination, sperm asters appeared; at 5 min post-insemination, eggs extruded secondary polar body; at 7 -15 rain post-insemination, male pronucleus and female pronucleus moved closer to each other and fused finally, forming a clear junction line; subsequently, zygote nucleus formed and karyotheca became faint; at 15 min pest-insem- ination, first karvokinetic division was develoued.

Identification of Epinephelus malabaricus and Epinephelus coioides using DNA markers

Using multi-molecular marker technologies and based on morphological criteria, the genetic relationship between Epinepheelus malabaricus and E, coioides was examined in the hope of resolving the long-standing issue of identifying these two species. Results showed that： （ 1 ） E. coioides and E. malabaricus should be identified as two species, the consistency of mitochondrial DNA cytochrome b gene sequence between E. malabaricus and E. coioides is 94.4%, and the genetic similarity by AFLP was 0.753 9 ; （2） Hybridization exists between E. malabaricus and E. coioides, the specific RAPD and AFLP fragments are found to be useful in the identification of these two species, and the genetic properties （both with exterior and inheritance） of hybrid is significantly biased to the male parents ; and （3） AFLP was a potentially powerful tool in constructing the genetic linkage map for these two groupers.

鞍带石斑鱼Epinephelus lanceolatus卵子的短期保存

在水产养殖中,建立体外保存卵子的方法对于人工授精和种苗生产具有重要的应用价值。鞍带石斑鱼Epinephelus lanceolatus是我国重要的水产养殖鱼类,其受精卵价格昂贵。本研究探讨了保存条件(保存介质、温度和pH)与添加剂(鞍带石斑鱼血清、维生素预混料)对于鞍带石斑鱼卵子短期保存的影响。结果表明,22℃时,卵子在L-15培养基(pH=8.1)中保存2 h,受精率和孵化率分别为66.4%和47.9%。在此基础上,添加鞍带石斑鱼血清和维生素预混料可以有效地延长保存时间,卵子能维持较高的活力。在体外保存8 h后,卵子的受精率和孵化率仍可达到64.4%和44.8%。本研究通过优化改良,建立了一种适合于鞍带石斑鱼卵子体外短期保存的体系,有助于鞍带石斑鱼的育种工作和孵化管理。

Diagnosis of nervous necrosis virus in orange-spotted grouper,Epinephelus coioides, by a rapid and convenient RT-PCR method

Viral nervous necrosis （VNN） causes high mortality in marine fish, especially in the grouper, worldwide and in China. Since there is no effective vaccine or drug to deal with VNN, early detection and prevention is important to block its outbreak. In this study, a reverse transcription-polymerase chain reaction （RT-PCR） was developed for the rapid, convenient, and sensitive detection of the VNN pathogen, nervous necro- sis virus （NNV）, in the grouper. The whole process was completed within 3.5 h from the RNA extraction to PCR product visualization. The detection limit of this method was 200 copies of NNV RNA standard, which corresponded to 200 copies of virus particles. This RT-PCR method was specific to the NNV detection with no cross-reactivity to other fish viral disease pathogens, such as infectious pancreatic necrosis virus （IPNV）, infectious hematopoietic necrosis virus （IHNV）, spring viraemia of carp virus （SVCV）, epizootic haematopoietic necrosis virus （EHNV）, and large yellow croaker iridovirus （LYC1V）. With this method, the orange-spotted grouper （Epinephelus coioides） fry from hatcheries with or without incidence of the VN- N epidemic in Fujian Province were detected. The results showed that all or 93% of the fry from the two hatcheries with incidence of the epidemic were diagnosed as positive, while 40% or 25% of fry from the t- wo hatcheries without the VNN epidemic were also detected as NNV positive, indicating that this RT-PCR method can be used for rapid, sensitive detection of NNV infection and applied in the VNN epidemic alert.

Characterization of the Complete Mitochondrial Genome of the Hybrid Epinephelus moara♀ × Epinephelus lanceolatus♂,and Phylogenetic Analysis in Subfamily Epinephelinae

This study presents the complete mitochondrial genome of the hybrid Epinephelus moara♀× Epinephelus lanceolatus♂. The genome is 16886 bp in length, and contains 13 protein-coding genes, 2 r RNA genes, 22 t RNA genes, a light-strand replication origin and a control region. Additionally, phylogenetic analysis based on the nucleotide sequences of 13 conserved protein-coding genes using the maximum likelihood method indicated that the mitochondrial genome is maternally inherited. This study presents genomic data for studying phylogenetic relationships and breeding of hybrid Epinephelinae.

Characterization and expression analysis of an allograft inflammatory factor-1 homologue in yellow grouper (Epinephelus awoara)

Allograft inflammatory factor-1 （ AIF-1 ） is a cytoplasmic calcium-binding protein involved in inflammatory response-related diseases in mammals. Previously an identified AIF-1 gene was simply reported in yellow grouper. The characterization of AIF-1 gene and its expression at the gene and protein level are further described. Yellow grouper AIF-1 is composed of 147 amino acids, and 64% ~ 84% identical to other homologues. Basal level AIF-1 mRNA expression was noted in spleen, anterior kidney and kidney, using reverse-transcription polymerase chain reaction （RT-PCR）. After stimulation of LPS, the AIF-1 mRNA expression was up-regulated in tissues examined： spleen, anterior kidney, kidney, heart and liver, but not in muscle. The recombinant AIF-1 protein was expressed in Escherichia coli, and then purified for the development of antiserum. Western blotting analysis revealed a band with a molecular mass of about 17 ku.

Protective immunity of orange-spotted grouper(Epinephelus coioids) against a nervous necrosis virus isolated from China,and determination of the complete sequences of the virus

On the basis of the sequence and analysis of genome from the orange-spotted nervous necrosis virus（ OGNNV）, China strain, a pair of special primers were designed according to the nucleotide sequences of RNA2 from OGNNV. The major capsid protein （ MCP）gene of OGNNV was cloned by means of reverse-transcriptase polymerase chain reaction （RT-PCR） and ligated into the pET32a expression plasmid. The MCP gene of OGNNV was 1 017 bases, encoded a protein of 338 amino acid with a molecular mass of 37.1 kDa. Recombinant protein with a molecular mass of 57.4 kDa was expressed in E. coli BL21 （DE3）. Vaccine was prepared from the recombinant protein expressed in recombinant cells. The juvenile orange-spotted groupers （8 cm in average length） were immunized by intraperitoneal injection. Group A was challenged with infected tissue filtrates 25 d post-vaccination. The mortality in the vaccined group （ A1,30% ） was a little higher than the unvaccined group （ B2, 27.8% ）. Group B was challenged after three vaccine injections. The mortality in the vaccined group （B1, 16.7% ） was lower than the unvaccined group （132, 27.8% ）, And the relative percentage survival （RPS） value of vaccined group, compared with the unvaccined group, was 40%. The anti-recombinant protein sera with a 1 ： 100 dilution were mixed with double volume of infected tissue filtrates and incubated at 4 ℃ for 12 h and then intramuscularly injected into the juvenile orange-spotted grouper. Treatment of infected tissue filtrates with anti-recombinant protein serum resulted in a significantly lower mortality of fish （ Group C1, mortality of 18.18% ）, compared with the fish （ Group C2, mortality of 40% ） which received infected tissue filtrates treated with control serum. Results implied the potential use of the capsid protein in immunization against OGNNV.

DISEASE RESISTANCE AND HUMORAL IMMUNOMODULATORY EFFECTS OF VITAMIN C ON GROUPER, EPINEPHELUS AWOARA

The disease resistance and humoral immunomodulatory effects of vitamin C administered orally to grouper, Epinephelus awoara maintained on a frozen fish diet supplemented with vitamin C at 500, 1000, 1500 and 2000 mg/kg were investigated. After 20 weeks, the growth rates of the groups with high level of vitamin C apparently increased. The untreated fish had symptoms of vitamin C deficiency. The endogenous liver tissue vitamin C levels were found to reflect well the dietary treatments. After intraperitoneal injection or bath challenge with a virulent strain of Vibrio vulnificus , fish fed with high level vitamin C showed significantly higher survival rate compared with the normal control group. Vaccination with formalin inactivated V. vulnificus significantly enhanced the specific antibody production in fish treated with vitamin C, and completely protected from strong bacterial challenge the groups fed on fish with vitamin C 1500 and 2000 mg/kg diet.

Effects of Temperature and Salinity on Oxygen Consumption and Ammonium Excretion Rate of ♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus Juveniles

The impact of water temperature(24, 27, 30 and 33℃) and salinity(15, 20, 25, 30 and 33) on oxygen consumption(OCR) and ammonium excretion rate(AER) of ♀ Epinephelus fuscoguttatus ×♂ E. lanceolatus hybrid grouper juveniles(9.39 ± 0.07 g) were investigated under the fed and un-fed conditions. The results showed that the OCR and AER were significantly(P < 0.05) affected by temperature and salinity under both fed and un-fed conditions. When temperature was 24–33℃, the OCR and AER of fed hybrid grouper juveniles were 85.68%–129.52% and 125.78%–287.63%, respectively, higher than those of un-fed hybrid grouper juveniles. The O/N ratio, protein use(P_u), Q_(10)(respiration) and Q_(10)(excretion) of fed hybrid grouper juveniles were 14.43–24.01, 28.35% – 48.48%, 1.69 and 3.01, respectively. The O/N ratio, P_u, Q_(10)(respiration), Q_(10)(excretion) of un-fed hybrid grouper juveniles were 20.39 – 31.79, 22.16% – 34.34%, 1.23 and 1.17, respectively. When salinity was 15–33, the OCR and AER of fed hybrid grouper juveniles increased by 87.42% – 116.85% and 215.38% – 353.57%, respectively, over those of un-fed hybrid grouper juveniles. The O/N ratio and P_u of fed hybrid grouper juveniles were 14.48 – 17.78, 39.36% – 49.43%, respectively. The O/N ratio and Pu of un-fed hybrid grouper juveniles were 20.39 – 31.79 and 22.16% – 34.34%, respectively. The specific dynamic action(SDA) of hybrid grouper juveniles was mainly related to protein metabolism. The results had a guiding significance to the large-scale intensive aquaculture of hybrid grouper juveniles.

Study on the Release of Grouper Epinephelus for Stock Enhancement

Two methods, tagging and ink injection, are used in the grouper releasing experiment. The studied fishes are the juvenile of Epinephelus akaara and Epinephelus awoara both artificially cultivated and caught from natural waters, and their wild adults. Experimental results show that the inhabiting behaviours for both juvenile and adult fishes show distinct regionality, which move within an area of 2 n mile diameter 651 days and 48 days after being released, respectively. With the tagging method, the tagged fishes could only be recaptured in the year of release while, with the injection method, they could be caught in the lst, 2nd and 3rd years. It is confirmed that in the cement tank, the tagged fishes lose their 1/3 tags. That means that the tagging method is not fit for the release research while the injection method is. Generally, the recaptured rates of injected fishes are 1.4 ～ 4.5 %, 3.1 ～ 13.4 % and 2.7 % for the 1st, 2nd and 3rd years, respectively.

Effects of Temperature and pH on Embryonic Development and Survival Rate of Newly Hatched Larvae of Epinephelus fuscoguttatus

The effects of temperature and pH on embryonic development and survival rate of newly hatched larvae of Epinephelus fuscoguttatus were discussed by single factor experiment method. Under a salinity of 31‰, fertilized eggs were incubated at different temperatures （17, 20, 23, 26, 29 （eontrol）, 32, 35 ℃ ） and different pH values （5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.4 （control）, 8.5, 9.0, 9.5 and 10.0）, the development rate of fertilized eggs, hatching rate, deformity rate, survival rate of newly hatched larvae, and optimum temperature and pH ranges for embryonic development were recorded and analyzed. The results showed that the incubation period y required by fertilized eggs was in remarkably negative correlation with temperature x, y =4 017. 3x-15277 , R2 =0. 971 3. At 29 ℃, the hatching rate was the highest, up to 92.00% ; this temperature was corresponding to the lowest deformity rate of newly hatched larvae （ 1.09% ） ; corresponding effective accumulative temperature was also the lowest （437. 410 ℃ . h）, and significantly different from other experimental groups （P 〈 0.05 ） ; but on the contrary, corresponding survival rates at 24 and 48 h reached, respectively, 88.03% and 82. 97% which were significantly different from other experimental groups （ P 〈 0.05）. At the pH of 8.4 in the CK group and the pH of 8.5 of one experimental group, the embryonic development rates were the highest; con-esponding hatching rates of fertilized eggs were the highest, respectively, of 88.33% and 83.33% which were significantly different from other groups （P 〈 0.05） ; and corresponding survival rates at 24 and 48 h were the highest, and reached 90.84% and 85.03%, respectively. In the pH range of 8.0 - 8.5, the deformity rate of newly hatched larvae was 0. It was indicating that for embryonic development of E. fuscoguttatus, the suitable water temperature value was in the range of 17 - 29 ℃, the optimum value was in the range of 23 -29℃; and the suitable pH value was in the range of 6.5 -9.5, and the optimum value was in the range of 8.0- 8.5.

High-throughput simple sequence repeat (SSR) markers development for the kelp grouper (<i>Epinephelus bruneus</i>) and cross-species amplifications for Epinephelinae species

The kelp grouper (Epinephelus bruneus), belonging to one of the largest genera among the subfamily Epinephelinae, is a commercially important fish in Japan. There are limited data about the genomics of this species. To provide tools for addressing both population genetics studies and gene mapping, dito pentanucleotide simple sequence repeat (SSR) markers were developed using 454 pyrosequencing. Among the 1466 SSR markers developed, 1244 primer sets produced strong PCR products, of which 905 (72.7%) were polymorphic in kelp grouper. Cross-species utility of the 905 polymorphic SSR markers was tested in four additional Epinephelinae species of Hyporthodus septemfasciatus, Plectropomus leopardus, Epinephelus lanceolatus and Epinephelus coioides. Results revealed that, respectively, 401 (44.3%), 136 (15.0%), 434 (49.0%) and 538 (59.4%) SSRs showed specific polymorphic products. Of these, 40 SSR markers (33 di-, 1 tri- and 6 tetra-nucleotides) showed polymorphism in all species tested. Additionally, three AGAT SSR motifs which accounted for 42.9% of the nondi-nucleotide markers were found in the 40 SSR markers. This indicates that the AGAT SSR motif has a high potential as a highly versatile SSR marker in grouper Epinephelinae. The SSR markers developed in this study can be employed to obtain reliable genetic variability estimates for groupers (Epinephelinae).

短期饥饿对杂交石斑鱼(Epinephelus fuscogutatus♀×E.polyphekadion♂)幼鱼消化酶活性与血清生化指标的影响

为了解短期饥饿对杂交石斑鱼(Epinephelus fuscogutatus♀×E.polyphhekadion♂)幼鱼消化酶活性和血清生理生化指标的影响,对杂交石斑鱼幼鱼进行短期饥饿处理(0 d、5 d、10 d、15 d),分别为S0组、S1组、S2组和S3组,并以S0组为对照组。结果表明,随着饥饿时间的延长,各种消化酶活性呈下降趋势,淀粉酶活性呈先上升后下降趋势。血清碳水化合物、胆固醇、甘油三酯、总蛋白、白蛋白等生化指标在饥饿前期显著降低(P<0.05),随后维持在相对稳定的水平。AST、ALT、ALP活性呈“下降-上升-下降”趋势。分析表明,在短期饥饿过程中,杂交石斑鱼幼鱼早期主要消耗碳水化合物和脂肪物质,后期主要以蛋白质代谢能量来维持生命活动,短期饥饿并没有对杂交石斑鱼造成不可逆转的肝脏损伤。

Molecular Characterization and Expression Analysis of SKIV Infection of Interferon-Induced Protein with Tetratricopeptide Repeats 1(IFIT1) in Epinephelus lanceolatus

Interferon-induced protein with tetratricopeptide repeats 1(IFIT1), also known as interferon-induced protein 56(IFI56) or Interferon-stimulated protein 56(ISG56), was originally identified as a protein induced upon treatment with interferon and inhibited by viral replication and translational initiation. In this study, Epinephelus lanceolatus IFIT1(ELIFIT1) gene was cloned for the first time. The complete cDNA of El IFIT1 gene includes 2921 nucleotides, and encodes a 437-amino acid(AA) protein. The putative ELIFIT1 protein has 9 TRP domains and is highly similar with IFIT1 proteins in other teleosts. In healthy fish, ELIFIT1 gene was highly expressed in the blood, which indicate its specific function in the peripheral immune system. Its expression was also observed in various immunity-related tissues including spleen, intestine, and kidney, Inducted with spotted knifejaw iridovirus(SKIV), ELIFIT1 gene expression was upregulated in the spleen, kidney, and liver 24 h after induction and reached its peak at 72 h, indicating that ELIFIT1 may play an important role in antivirus. These findings contribute to the understanding of the antiviral regulation of ELIFIT1 gene in teleost.

虎龙杂交斑(Epinephelus lanceolatus♂×E. fuscoguttatus♀)对20种常见氨基酸的嗅觉电生理反应

虎龙杂交斑(Epinephelus lanceolatus♂×E.fuscoguttatus♀)是我国重要的石斑鱼养殖品种,为研究其对20种常见氨基酸的不同嗅觉反应,筛选出对虎龙杂交斑嗅觉具有高效刺激性的单体氨基酸,通过嗅上皮水下嗅电位法(electro-olfactogram,EOG)得出了虎龙杂交斑对20种常见氨基酸的嗅觉反应差异和对5种氨基酸的嗅觉反应阈值,并讨论了氨基酸分子结构与嗅觉刺激效果之间的关系。结果表明:氨基酸的种类和浓度均对虎龙杂交斑嗅觉刺激反应有影响,虎龙杂交斑对含5~6个碳原子、无支链的中性脂肪族含硫氨基酸反应强烈,一个例外是对含3个碳原子的半胱氨酸有较强反应。10^(-6)mol/L的蛋氨酸刺激液对虎龙杂交斑嗅觉的刺激性最强,10^(-2)mol/L脯氨酸刺激液对虎龙杂交斑嗅觉的刺激性最弱。虎龙杂交斑嗅觉反应幅值(y)随5种氨基酸刺激液浓度对数值(x)的增大而呈指数升高趋势,在试验中虎龙杂交斑嗅觉反应幅值没有随5种氨基酸刺激液浓度对数值的增大而达到平台期。从反应阈值中反应幅值与氨基酸刺激液浓度的关系方程式可得出反应阈值浓度为10;~10;mol/L。研究结果有助于为虎龙杂交斑诱食剂和饲料配制的研究提供依据。

The mechanism of retinomotor movements in the retina of banded grouper (Epinephelus awoara)

In order to clarify the mechanism of retinomotor movements in banded grouper, this paper utilizes inhibition factors of microfilaments and microtubules cytochalasin-B and colchicine to study the roles of actin microfilaments and microtubules in the movements of the REP pigment granles and cones. It provides evidences to explain the mechanism of retinomotor movements in fish.

Soybean meal as a source of protein in formulated diets for tiger grouper, <i>Epinephelus fuscoguttatus</i>juvenile. Part II: Improving diet performances

The present study was conducted as a continuation of our previous study on the effects of fish meal replacement with soy bean meal, SBM in the diets of tiger grouper, Epinephelus fuscoguttatus which revealed the possible level of fish meal protein replacement of 30% with positive effect of phytase supplementation in one of the test diet. In the present study, all experimental diets with SBM inclusion (10%, 20%, 30%, 40% replacement levels) were supplemented with phytase and fed to juvenile tiger grouper with initial body weight of 44.57 ± 0.28 g for eight weeks. Apart from the effects on growth performance, diet utilization and fish whole-body composition, apparent digestibility coefficient of diets was also measured. Similar findings to our previous experiment were observed in the present study. Diet SM40P (40% replacement level) had produced the poorest growth performance and feed conversion ratio (FCR). However, it was observed that FCR of SM40P was improved when compared to SM40 (without phytase) in our previous experiment. Other than that, SBM-based diets were performed as good as the control diet in terms of growth, feed utilization and survival rate. Replacement of fish meal did not significantly influence body composition, except for whole body lipid content in SM40P. In general, dry matter and protein apparent digestibility coefficients (ADC) of the test diets were influenced by SBM inclusion in the diets. However, crude lipid ADC was very high in all dietary treatments indicating efficient utilization of dietary lipid by juvenile tiger grouper. The findings of the present study confirmed that SBM can be used to replace FM at a level of up to 30% and supplementation of phytase in SBM-based diets is recommended to improve the diet performance.

Soybean meal as a source of protein in formulated diets for tiger grouper, <i>Epinephelus fuscoguttatus</i>juvenile. Part I: Effects on growth, survival, feed utilization and body compositions

The effects of fish meal (FM) replacement with graded level of soybean meal (SBM) on growth performance, feed utilization, survival rate and body composition were investigated in juvenile tiger grouper, Epinephelus fuscoguttatus (initial body weight 13.9 ±0.65 g). Six experimental diets were formulated to contain 50% crude protein, 16% crude lipid and 365.8 kcal/100g feed with SBM replacing FM protein at 0% (SM 0), 10% (SM 0), 20% (SM 20), 30% (SM 30), 40% (SM 40) and 20% with phytase (SM 20P) replacement levels. At the end of the ten-week feeding trial, there were no significant differences detected in terms of growth performances (weight gain and specific growth rate), feed conversion ratio (FCR) and survival rates of fish fed with the control diet (SM 0), SM 20, SM 30 and SM 20P. Net protein utilization of fish fed SM 20P was higher than those fed with other diets suggesting an improved utilization of nutrients with phytase addition in the diet. Replacements of FM protein with SBM at 10% and 40% have resulted in significantly lower growth and poorer FCR than other replacement levels. Survival rates remain high (≥90%) throughout the trial. Whole-body proximate composition of the fish was significantly affected by the inclusion of SBM in the diets. It can be concluded that 20%-30% of FM protein replacement with SBM is recommended and addition of phytase in the SBM-based diet should be considered to improve nutrient utilization of tiger grouper juvenile.