Difference in the level of paralytic shellfish poisoning toxin accumulation between the crabs <Emphasis Type="Italic">Telmessus acutidens</Emphasis> and <Emphasis Type="Italic">Charybdis japonica</Emphasis> collected in Onahama,Fukushima Prefecture

ABSTRACT:     The difference in paralytic shellfish poisoning (PSP) toxin accumulation in the crabs Telmessus acutidens and Charybdis japonica was investigated at Onahama, Fukushima Prefecture, from 2002 to 2005. The level of toxin accumulation in the hepatopancreas of T. acutidens corresponded to that of mussels when examined on a yearly basis. In 2003, some crabs had a high toxicity of approximately 1000 MU, which compares to one-third of the human minimum lethal dose. Therefore T. acutidens should be monitored as a vector species of PSP toxin. The toxin profile of T. acutidens was also investigated. Because an increase in highly toxic species of PSP toxins with a decrease in low toxic species, such as N -sulfocarbamoyl-11-hydroxysulfate toxins, was not clearly observed between consecutive samples, toxin transformation in T. acutidens was considered to have a minimal impact on toxicity. PSP toxins were also detected in several specimens of C. japonica , but the highest toxicity was only 7.4 MU/g in the hepatopancreas. Because C. japonica is widely distributed in the coastal waters of Japan, investigation of toxin accumulation in the crab should be continued, including its investigation in different areas of water from Onahama, where the causative dinoflagellates of PSP occur in different conditions.     

Comparison between α-LNA and DHA in early developmental stages of <Emphasis Type="Italic">Takifugu obscurus</Emphasis> and <Emphasis Type="Italic">Takifugu rubripes</Emphasis>

ABSTRACT:   Rearing experiments were conducted to investigate the essential fatty acid requirements in the early developmental stages of river puffer Takifugu obscurus and tiger puffer T. rubripes using two n-3 series unsaturated fatty acids, α-linolenic acid (18:3n-3, α-LNA) and docosahexaenoic acid (22:6n-3, DHA), under salinity of 30 and 18.5–20.3°C. River and tiger puffer larvae used in this study were 15 and 14 days old after hatching, and their average body weights were 30.1 and 20.8 mg, respectively. The results on fatty acid requirements of these two species were evaluated from fish growth, survival, fatty acid composition of the fish body and activity test results. The DHA groups of both river and tiger puffer exhibited better survival and weight gain. However, there was no difference in the mean final body weights of river puffer between two dietary groups. Also, the DHA group of tiger puffer showed better results in the recovery test from anesthetic condition than that obtained in the LNA group. In an examination of the fatty acid compositions of the whole body, the LNA group containing no dietary DHA resulted in 0.5% DHA in tiger puffer and 1.1% DHA in river puffer . These results suggest that α-LNA from Artemia converted to eicosapentaenoic acid (20:5n-3, EPA) and to DHA successively by their fatty acid metabolism. Symptoms following essential fatty acid deficiency were not observed in any experimental groups. As river puffer did not represent a significant difference in the dietary effects between α-LNA and DHA treatment groups, its essential fatty acid requirement was assumed to be somewhat closer to that of the freshwater fishes in comparison with that of marine fishes, including tiger puffer.     

Effects of fish size and water temperature on the acute toxicity of boron to Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> and red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis>

ABSTRACT:     The acute toxicities of boron were examined for Japanese flounder Paralichthys olivaceus and red sea bream Pagrus major in terms of fish size and water temperature. Japanese flounder of 0.1–70.0 g and red sea bream of 0.6–20.3 g were exposed to different concentrations of boron for 96 h at 20°C under semi-static conditions. In both fish species, the median lethal concentration (LC₅₀) for 96 h of boron increased linearly with increasing fish size, ranging from 108 to 252 mg B/L for the flounder, and from 97 to 172 mg B/L for the sea bream. The effect of water temperature on acute toxicity was examined for Japanese flounder of 0.6 and 1.5 g at 10, 15, 20 and 25°C, and for red sea bream of 0.6 and 2.4 g at 12, 15, 20 and 25°C. The toxicity of boron for the flounder increased linearly with increasing water temperature. The 96 h LC₅₀ values ranged from 299 to 108 mg B/L for the 0.6 g flounder and from 350 to 113 mg B/L for the 1.5 g flounder. A similar trend was shown for the 2.4 g red sea bream; however, the relationship for the 0.6 g red sea bream was not significant.     

Induction of (<Emphasis Type="Italic">Z</Emphasis>)-8-heptadecene in marine green alga <Emphasis Type="Italic">Bryopsis maxima</Emphasis> by mechanical wounding

ABSTRACT:   After mechanical wounding of the marine green alga Bryopsis maxima in a phosphate buffer, one main organic component was released to the solution. The organic compound was characterized by a molecular ion at 238  m/z by gas chromatography–mass spectrometry (GC-MS) and was deduced as 8-heptadecene by the fragment pattern. To identify the stereochemistry of 8-heptadecene, synthetic ( Z / E )-8-heptadecene was coinjected to the solution of wounded B. maxima . Comparing retention times and mass spectra with the synthetic sample, the target hydrocarbon obtained from wounded B. maxima was coincident with ( Z )-8-heptadecene.     

Chemical composition of dried eyeballs from <Emphasis Type="Italic">Euphausia superba</Emphasis> and <Emphasis Type="Italic">Euphausia pacifica</Emphasis>

ABSTRACT:   Dried krill eyeballs were obtained from Euphausia superba and Euphausia pacifica by using a patented industry method and their chemical compositions were examined. Crude protein content was 77.7% and 80.8% of the dry matter of E. superba and E. pacifica , respectively. The dominating amino acids in both krill were glutamic acid, aspartic acid, glycine, arginine, leucine and tyrosine. Crude fat content was 10.9% and 5.4% of dry matter of E. superba and E. pacifica , respectively. The main lipid class of the extracted lipids was phospholipids at 88.5% in E. superba and 96.4% in E. pacifica . The dominating fatty acids in both krill were 22:6 ( n- 3), 20:5 ( n- 3), 16:0 and 18:1 ( n- 9). Astaxanthin (3, 3'-dihydroxy-β, β-carotene-4, 4'-dione) content of E. superba and E. pacifica was 566 mg/100 g and 252 mg/100 g of dry matter, respectively. Retinol of E. superba and E. pacifica was 153.0 mg/100 g (510 000 IU/100 g) and 57.6 mg/100 g (192 000 IU/100 g) of dry matter, respectively. The lipophilic extract of E. superba by using n -hexane contained 1923 mg/100 g of astaxanthin at approximately four times higher than the dried eyeballs.     

Species identification method for <Emphasis Type="Italic">Scombrops boops</Emphasis> and <Emphasis Type="Italic">Scombrops gilberti</Emphasis> based on polymerase chain reaction-restriction fragment length polymorphism analysis of mitochondrial DNA

ABSTRACT:   Gnomefish Scombrops boops and Scombrops gilberti are commercially important fishes in Japan, but these species are often confused in the markets because of their morphological similarity. To identify these two species, we performed nucleotide sequencing and restriction fragment length polymorphism (RFLP) analysis on 16S ribosomal RNA (rRNA) gene and the control region in mitochondrial DNA. Five and 12 nucleotide substitutions were observed between species in the 777-bp 16S rRNA gene and 471-bp control region, respectively. Diagnostic restriction sites for discriminating between S. boops and S. gilberti were found in the 16S rRNA gene, but not in the control region. Polymerase chain reaction (PCR)–RFLP analysis using two enzymes, Eco NI and Mva I, clearly discriminated between S. boops and S. gilberti identified by meristic characters. The PCR–RFLP analysis identified most of the 168 Scombrops young caught in the coastal waters of the Izu and Miura peninsulas as S. boops , suggesting that S. gilberti juveniles are rare in this area.     

Genetic comparison between torafugu <Emphasis Type="Italic">Takifugu rubripes</Emphasis> and its closely related species karasu <Emphasis Type="Italic">Takifugu chinensis</Emphasis>

Abstract:   Sequence analyses of mitochondrial (mt) and nuclear genes were performed for genetic comparison between two Takifugu pufferfish species: torafugu T. rubripes and karasu T.  chinensis . With a sequence coverage of 20% in mtDNA, 640, 308, 344, 522 and 697 bp encoding mt 16S ribosomal RNA (rRNA), adenosine triphosphatase 6 ( ATPase 6 ), nicotinamide adenine dinucleotide dehydrogenase subunit 4 ( ND4 ), ND5 and cytochrome b (cyt b ), respectively, among 24 wild torafugu, 24 wild karasu and six hybrid-like samples, 15% of the torafugu identified by external color patterns showed nucleotide sequences consistent with karasu. Meanwhile, sequences of 60% karasu were consistent with those registered for torafugu (AJ421455). As for the hybrid-like samples, two possessed karasu-specific sequences in some base positions while torafugu-specific sequences in others. The remaining hybrid-like samples possessed torafugu-specific sequences. On the other hand, the mt control region did not show such type of consistency. Analysis of nuclear melanocortin receptor genes ( MC1R , MC4R ) among 54 samples showed 99–100% inter- and intraspecific sequence identity. Partial nuclear 18S  rRNA, complete internal transcribed spacer 1 ( ITS1 ), partial 5.8S  rRNA and ITS2 genes showed similar levels of identity, indicating a very low level of variation in their respective gene fragments between the two Takifugu species.     

Optimum temperature and salinity conditions for growth of green algae <Emphasis Type="Italic">Chlorella ellipsoidea</Emphasis> and <Emphasis Type="Italic">Nannochloris oculata</Emphasis>

ABSTRACT:   The effects of temperature and salinity on growth of green algae Chlorella ellipsoidea and Nannochloris oculata were determined to compare the optimum culture conditions. A four-temperature (15, 20, 25, and 30°C) × three-salinity (10, 20, and 30) factorial design with triplicates was applied. Specific growth rate (SGR), maximum density, and duration to reach maximum density of C. ellipsoidea were significantly affected by both temperature and salinity. The highest SGR was observed in C. ellipsoidea at 25°C and salinity 10, but the maximum density was very low. The highest maximum density was achieved in C. ellipsoidea at 15°C and 10. The slope constant of the linear relationship between semilogarithmic growth of C. ellipsoidea and day of culture was highest at 15°C and 10. The SGR and duration to reach maximum density of N. oculata were significantly affected by both temperature and salinity. However, maximum density of N. oculata was significantly affected by temperature, but not salinity. The highest maximum density was achieved in N. oculata at 25°C and 30, but SGR was significantly lower than that of N. oculata at 25°C and 10. The slope constant of the linear relationship between semilogarithmic growth of N. oculata and day of culture was highest at 25°C and 30. Based on these results, the condition of 15°C and salinity 10 seemed to be optimal for maximum density of C. ellipsoidea , and the condition of 25°C and 10 and 30 for SGR and maximum density for N. oculata , respectively.     

Effect of combination feeding of <Emphasis Type="Italic">Nannochloropsis</Emphasis> and freshwater <Emphasis Type="Italic">Chlorella</Emphasis> on the fatty acid composition of rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> in a continuous culture

ABSTRACT:   A continuous culture of rotifer was conducted to investigate the effect of combination feeding of both a high density of Nannochloropsis oculata (N) and condensed freshwater Chlorella (FC) on the fatty acid composition of L-type rotifer Brachionus plicatilis in a continuous culture system. The algal feeding of the rotifers was carried out in three successive steps: N-feeding → N+FC-feeding → FC-feeding. The culture was conducted at 24°C and 25–27 psu in a 2000 mL bottle with 50% of water exchanged daily. The combination N+FC-feeding was effective in increasing rotifer density. The rotifers fed on N+FC (N+FC-R) had more non-polar lipids than polar ones, similar to those on N (N-R), opposite to the rotifers fed on FC (FC-R). N+FC-R contained higher levels of 16:2, 18:2n-6 (linoleic acid [LA]) and 20:2n-6, but lower levels of 18:1, 20:4n-6 (arachidonic acid), 20:5n-3 (eicosapentaenoic acid [EPA]) and 22:5n-3 (docosapentaenoic acid [DPA]) compared with N-R. Whereas N+FC-R contained higher levels of 16:1n-7, EPA and DPA, but lower levels of 16:2 and LA compared with FC-R. N+FC-R had more DPA in polar lipids than in non-polar ones. The Σn-6/Σn-3 ratio in N+FC-R was 0.9–1.0, significantly different from those in N-R (0.4) and FC-R (6.6–8.4). Therefore, it is inferred that the fatty acid profile of the N+FC-R cultured in a continuous culture system was affected by both N and FC. Also, the combination N+FC-feeding may be effective in manipulating the Σn-6/Σn-3 ratio in continuously cultured rotifers.     

Multigenerational effects of 17β-estradiol and nonylphenol on euryhaline cladoceran <Emphasis Type="Italic">Diaphanosoma celebensis</Emphasis>

ABSTRACT:     The effects of parental exposure to 17β-estradiol (E2) and 4-nonylphenol (4-NP) on life history parameters of three successive generations of the euryhaline cladoceran Diaphanosoma celebensis were assessed under laboratory conditions. Less than 24-h-old neonates (P) were exposed to five sublethal concentrations of E2 (0.1, 1, 10, 100 and 1000 μg/L) and 4-NP (0.01, 0.1, 1, 10 and 50 μg/L) at 25°C. Age at first reproduction, reproductive period, fecundity and lifespan were investigated. Successive generations (F₁–F₃) were monitored further in the absence of toxicants. Results showed that cladocerans exposed to 10–1000 μg/L E2 produced more neonates at a younger age compared to the control. The same effects were also observed in the F₁ and F₂ but ceased in F₃. Cladocerans exposed to 1 μg/L 4-NP also produced significantly more neonates compared to the control, but this effect was not found in successive generations. The results suggest that vertebrate hormone can modify the reproduction of D. celebensis , and the effects are multigenerational.     

Fortification of <Emphasis Type="Italic">niboshi</Emphasis> with histidine prepared from <Emphasis Type="Italic">katsuobushi</Emphasis> protein digest

ABSTRACT:   Free and total histidine contents in the muscle of various fishes and invertebrates caught in the Seto Inland Sea were estimated. These contents were higher in the muscles from skipjack, yellowfin tuna, yellowtail and mackerel than in those from lizard fish, sea bream and hairtail. Invertebrate muscles, except squid, contained low free and total histidine. Boiled and dried anchovy ( niboshi ) contained lower free histidine than that of dried anchovy (suboshi). To prepare free histidine-rich extracts, the waste residue of soup stock from smoke-dried and shaved skipjack ( katsuobushi ) was digested with proteases. The extract of the enzyme digest contained high free histidine and was used to fortify niboshi with free histidine. If taken, the fortified niboshi may suppress food intake, and prevent obesity.     

Genetic identification of <Emphasis Type="Italic">Conger myriaster</Emphasis> leptocephali in East China Sea

ABSTRACT:   A subsample of Conger leptocephali collected in the East China Sea (ECS) was genetically analyzed and most were found to be the larvae of Conger myriaster , the most commercially important marine eel species in East Asia. However, these leptocephali (22.3–74.0 mm total length [TL]) did not have a complete row of lateral pigmentation, like the leptocephali of this species are commonly known to have when they are collected over the continental shelf or in coastal waters as they recruit. These leptocephali were in the western edge of the Kuroshio Current and the mixing zone over the shelf in the northern part of the ECS, and two smaller leptocephali (22.3, 46.5 mm TL) were collected to the south of the Ryukyu Islands. This evidence of an ontogenetic change in the presence of lateral pigmentation of C. myriaster indicates that previous efforts to determine the spawning area and recruitment patterns based on only morphological examination of Conger leptocephali in the region must be reconsidered. New research efforts based on genetic identification methods are needed to understand the spawning ecology and recruitment of this important fishery species.     

Effects of irradiance of various wavelengths from light-emitting diodes on the growth of the harmful dinoflagellate <Emphasis Type="Italic">Heterocapsa circularisquama</Emphasis> and the diatom <Emphasis Type="Italic">Skeletonema costatum</Emphasis>

ABSTRACT:   We investigated the effects of specific light wavelengths from light-emitting diodes (LEDs) on the growth of the dinoflagellate Heterocapsa circularisquama , which kills bivalves, and the diatom Skeletonema costatum , which is an important food source for bivalves. Growth of H. circularisquama was obviously inhibited at 590 nm and a photon flux density less than 75 μmol quanta/m²/s. However, growth of S. costatum was not suppressed by irradiance from any LEDs tested from near-ultraviolet to near-infrared wavelengths at 75 μmol quanta/m²/s. The growth rate of H. circularisquama in an experimental treatment group with irradiance provided by both cool-white fluorescent lamps (12:12 h L : D cycle) and a 590-nm LED (continuous irradiance) was 0.43/day. In the control group with irradiance provided only by cool-white fluorescent lamps (12:12 h L : D cycle), the growth rate was 0.63/day, indicating that growth of H. circularisquama was suppressed by 590 nm (less than 75 μmol quanta/m²/s) irradiance from the LED and the continuous irradiance. The use of 590-nm LEDs in bivalve culture at irradiance levels less than 75 μmol quanta/m²/s might encourage the growth of the useful diatom S. costatum without stimulating growth of the harmful dinoflagellate H. circularisquama .     

Maturation and spawning of <Emphasis Type="Italic">Spratelloides gracilis</Emphasis> Clupeidae in temperate waters off Cape Shionomisaki,central Japan

ABSTRACT:   The reproductive ecology of Spratelloides gracilis was investigated in the temperate waters off Cape Shionomisaki, central Japan. Cape Shionomisaki is located at the northern margin of the distribution range of this species. Females of S. gracilis with gonadosomatic index (GSI) ≥ 4.0 were defined as mature based on the relationship between GSI and the histological maturity phases of their ovaries. More than 50% of females greater than 60 mm standard length (SL) were mature. Hatch dates of larvae and juveniles collected in the study area were determined by otolith daily ring counts and found to extend from April to November. The size at maturity of females (60 mm SL) and the spawning season of S. gracilis in the temperate waters off Cape Shionomisaki (April–November) was larger and shorter, respectively, than those in tropical waters in the western Pacific. The reproductive traits observed for S. gracilis off Cape Shionomisaki appear to be adaptive to northern temperate waters with seasonal changes in environmental conditions.     

Recent expansion of Northeast Atlantic and Mediterranean populations of <Emphasis Type="Italic">Melicertus</Emphasis> (<Emphasis Type="Italic">Penaeus</Emphasis>) <Emphasis Type="Italic">kerathurus</Emphasis> (Crustacea: Decapoda)

We analysed the genetic diversity of Melicertus kerathurus (Penaeidae), a commercially valuable penaeid shrimp that is distributed in the Mediterranean Sea and eastern Atlantic Ocean. We examined the polymorphism of a 494 bp DNA segment of the mitochondrial COI region in 173 individuals, sampled in nine Mediterranean and two Atlantic samples, covering the whole range of the species from the tropical waters of the Gulf of Guinea to the eastern part of the Mediterranean Sea. The mean nucleotide and haplotype diversities were π = 0.00275 and h = 0.718, respectively, for the global data set, with the highest values occurring in the African samples and the lowest in the Adriatic Sea. A clear sample differentiation was found (F _st = 0.194), but this did not reflect a geographical pattern and there were only faint traces of an Atlantic–Mediterranean subdivision. Mismatch analysis and a high significant negative value of Tajima’s D suggested that M. kerathurus is not at mutation drift-equilibrium, but underwent a recent expansion after a period of low effective sample size. A postglacial recolonisation of the Mediterranean from an Atlantic refuge could be hypothesised based on these data.     

Bioaccumulation and distribution of trace elements in tissues of giant river prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis> (Decapoda: Palaemonidae) from South Vietnam

ABSTRACT:   Accumulation profiles of 22 trace elements in abdominal muscle, abdominal exoskeleton and the hepatopancreas of the giant river prawn Macrobrachium rosenbergii were analyzed. The giant river prawn is an indigenous freshwater species from South Vietnam, and is cultured commercially and fished in the wild. Samples were collected from Ho Chi Minh City and the surrounding area (SKEZ, South Key Economic Zone), and from the Mekong River Delta between 2003 and 2005. Highest accumulations of essential (Cu, Se and Mo) and toxic (As, Ag, Cd and Hg) elements were observed in hepatopancreatic tissue, except for Mn, Sr, Sn, Ba and V in the exoskeleton and Rb and Cs in muscle tissue. Spatial differences showed concentrations of Cs and Pb in muscle and Sr in exoskeletons from the SKEZ were higher than those from the Mekong River Delta. The opposite trend was observed for Cr, Se and Sb in muscle, Mo, Sb and Tl in exoskeleton, and Se, Hg, Mo, Cd, Sb, Tl and Bi in the hepatopancreas. These differences in trace element concentrations in prawns likely reflect differences in industrialization and human activities between the two regions of South Vietnam.     

Mortality of the short-neck clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> induced by the toxic dinoflagellate <Emphasis Type="Italic">Heterocapsa circularisquama</Emphasis>

Mortality of the short-neck clam Ruditapes philippinarum exposed to the toxic dinoflagellate Heterocapsa circularisquama was studied under controlled conditions to clarify the mechanisms of recurrent mass deaths of clams occurring in western Japanese coastal areas. One-week mortality tests, involving three water temperatures, six H. circularisquama concentrations, and two clam body sizes, showed a significant increase in mortality with increasing temperature, H. circularisquama concentration, exposure duration, and body size (ANOVA, P < 0.01). Clam death was observed at concentrations as low as 50 cells/ml and temperatures as low as 15°C. Prior to death, clams showed an extreme retraction of their mantle edge and siphon, along with recurrent vomiting behavior before initiating a closure reaction followed by paralysis then death. Gills of paralyzed clams showed an important uptake of dye, implying gill damage. This study is the first laboratory evidence of bivalve mortality induced by H. circularisquama at low concentrations and low temperature, and the first report of differential effects according to the body size of bivalves.     

Identification of razor clams <Emphasis Type="Italic">Ensis arcuatus</Emphasis> and <Emphasis Type="Italic">Ensis siliqua</Emphasis> by PCR-RFLP analysis of ITS1 region

ABSTRACT:   Ensis arcuatus and Ensis siliqua are the most economically important species of razor clams in the European Union. Due to similarities between their shell morphology, and the differing retail value, these species are often misidentified. Therefore, it is necessary to develop an appropriate protocol to allow accurate differentiation between these species of razor clam in order to protect consumer rights, avoid commercial fraud (whether intentional or unintentional), and to enforce labeling and safety regulations. With the aim of developing a rapid and reliable method of differentiation, individuals of E. arcuatus and of E. siliqua were examined by polymerase chain reaction restriction fragment polymorphism (PCR–RFLP) using the internal transcribed spacer region 1 (ITS1). A species-specific restriction endonuclease pattern was found with the enzyme Ksp I for both species, allowing their exact identification. Thus, this work provides a simple, reliable and rapid protocol for accurate discrimination between E. arcuatus and E. siliqua , which proves useful for traceability and enabling the enforcement of labeling regulations.     

Study of growth and body composition of red snapper <Emphasis Type="Italic">Lutjanus erythropterus</Emphasis> fed diets containing <Emphasis Type="Italic">Escherichia coli</Emphasis> expressing recombinant tilapia insulin-like growth factor-I

ABSTRACT:   To examine the effects of insulin-like growth factor (IGF)-I on the growth performance of fish, juvenile red snapper Lutjanus erythropterus with an initial body weight of approximately 12 g were fed diets containing different amounts of IGF-I containing Escherichia coli BL21 powder (BL21-tIGF-I). The growth of fish was enhanced by lower doses (0.25, 0.5 and 1%), but deteriorated at higher amounts (2.5 and 5%). The best results were obtained with 0.5% BL21-tIGF-I supplementation, which resulted in 154 and 85% weight gain and feed efficiency, respectively. In addition, muscle proteins appeared to be elevated, but muscle lipids were reduced except for in the 1% BL21-tIGF-I group. In contrast, liver lipids were reduced at 0.25, 0.5 and 1%, but increased at 2.5 and 5% BL21-tIGF-I. Furthermore, to examine the effects of BL21-tIGF-I on later-stage red snapper, we selected fish of approximately 23–24 g weight and fed them a diet either with or without 0.5% BL21-tIGF-I for 12 weeks. Results showed that the growth performance of later-stage fish was better with BL21-tIGF-I than those without supplementation after 6 weeks of feeding. The average body weight of fish that did not receive BL21-tIGF-I during the first 6 weeks, but were fed BL21-tIGF-I in weeks 7–12, was significantly higher than those fed without BL21-tIGF-I for the entire experiment. These results suggest that a continuous supply of BL21-tIGF-I may be beneficial for the growth performance of red snapper.