Abstract:In order to understand the value of changes in fatty acid composition during early developmental stage of tawny puffer Takifugu flavidus, the fatty acid composition and content of tawny puffer in different developmental stages (unfertilized eggs, embryos 80–85 h after fertilization, newly hatched larvae 0-day-age, and before feeding larvae 3-day-age) were detected and analyzed by biochemical analysis methods. The results show that the moisture of egg and fry increased significantly with ontogenesis; the total lipid contents of fry decrease significantly with ontogenesis. 8 saturated fatty acids (SFA), 7 mono-unsaturated fatty acids (MUFA), and 12 poly-unsaturated fatty acids (PUFA) were found in the dry samples at different developmental stages. There was very similar tendency in fatty acid composition between unfertilized egg and its parent ovaries. At the embryonic period, the order of utilization rate of fatty acid was SFA (15.08%), MUFA (14.46%), n6PUFA (10.20%), and n3PUFA (0.19%), and C16:0, C16:1, C18:1n9c, and C18:2n6c were main sources of energy metabolism, and n3PUFA was preserved by priority, especially DHA, which was fully retained. After hatched, at the endogenous feeding stage, utilization rate of n3PUFA rose rapidly, followed by n3PUFA (19.60%), n6PUFA (16.98%), SFA (13.50%), and MUFA (13.01%). This was reverse to the embryo; C18:2n6c, C22:5n3(DPA), C20:5n3(EPA), C22:6n3(DHA), C18:1n9c, and C16:0 were main sources of energy metabolism, and the highest practical utilized quantity was DHA (14.44 mg/g), n3PUFA (especially DHA) was largely consumed before the larvae feeding. Therefore, larval development of tawny puffer needs to consume large amounts of n3PUFA (especially DHA and EPA). In larval breeding of tawny puffer, in order to improve the survival rate of larvae, enhancement of bait enriched with DHA and EPA (e.g., seawater rotifera, and Artemia sp. nauplii enriched with algae) was suggested.

Abstract:In order to investigate the expression characteristics and transmission effects of immune factors between the female parent and the progeny of Ctenopharyngodon idella, after being vaccinated with GCRV attenuated vaccine to female grass carp (40 days old). the protein activity and gene expression levels of IgM, C3 and LSZ were detected in the blood of female parent during the early development embryos of progeny and juvenile fish. The activities of IgM protein in the blood, early embryos and juvenile stage of grass carp were significantly higher than those in the control group by GCRV attenuated vaccine. In each stage of progeny, the expression level of IgM protein was the highest on d 28, while the protein activity was the lowest on d 5. From the fertilized egg to the 3 d water stage, the protein activity of C3 and LSZ were significantly higher in the experimental group than those in the control group. The activity levels of IgM, C3 and LSZ proteins in both groups showed a trend from decline to rise. The activity levels of C3 and LSZ protein in the experimental group were significantly higher than those in the control group from the stages of egg cell to 3 d. The expression level of IgM gene had a big difference between the experimental group and control group, the expression level of the experimental group was 3.4 times that of the control group. From the period of organogenesis (24 h) to the stage of 3 d, the mRNA expression of C3 was significantly higher than that in the control group. From the egg cell to the blastula stage, the mRNA expression of LSZ was significantly higher than that in the control group. After being immunized by attenuated vaccine of GCRV, the mRNA expressions of IgM were significantly higher than those in the control group in the tissues of body kidney, head kidney and spleen of 2-month-old progeny. The number of death fish caused by the GCRV infection in the experimental group (2 fish died) was lower than that in the control group (5 fish died). The results showed that maternal immunization can transmit between generations, and it played an important role in the immune protection of progeny.

Abstract:To study the classification, compositon and the role of different types of hemocytes in immune response in Eriochior sinensis, we researched the composition and classification of hemocytes from E. sinensis using cytochemical assays, cytoenzymatic assays and morphological observation in this investigation. Meanwhile, total hemocyte counts (THC) and different hemocyte counts (DHC) were performed. Our results showed that hemocytes from E. sinensis were divided into four types: granulocytes (G), intermediate granulocytes (IG), semigranulocyte (SG) and hyalinocytes (H). SG got the highest percentage about 33.54% while IG got the lowest only about 15.31%. Only granulocytes showed positivity to acid phosphatase, alkaline phospatase, β-glucuronidase and phenoloxidase and all types of hemocytes contain polysaccharide but no lipid. In addition, the THC increased obviously at 3 h after the injection of Aeromonas hydrophilia and reached a peak at 6 h, which was significantly higher than blank and saline groups. The numbers of granulocytes declined dramatically and hyalinocytes increased at the same time during the infection of bacteria, and this phenomenon recovered to their normal level 6 h later. Therefore, we concluded that hyalinocytes perform phagocytosis with large numbers of proliferation while granulocytes perform release of the immune-related enzymes with cell lysis during the response in non-specific immunity in E. sinensis. In addition, there might be transformations between various types of hemocytes and intermediate granulocytes were the interim types during the transformation. Hemocyte classification in crustacean had been studied by several researchers but there was no final conclusion in this field. The method of three categories was adopted by most researchers. However, the author found that there was one intermidiate type of hemocytes and it would be helpful to the research of hemocytopoiesis and immune function of different types of hemocytes.

Abstract:The cytoskeleton such as microfilaments and microtubules play important roles in the mechanism of viral infection, replication release and virus-host cell interactions. In this study, the Singapore grouper iridovirus (SGIV) particles were purified and the viral envelopes were separated from the viral particle by detergent dissolution. The envelope proteins were identified by 1-DE-MALDI TOF and LC-MALDI TOF workflows. Except for viral proteins, 7 host proteins were found to exist in the envelope component including actin. Thus, these host proteins were co-purified with the viral particles. Actin was proved to exist with the envelope by Western-blot. Further, it was observed that the actin proteins existed on the surface of the virus particles by immnoelectron microscopy, suggesting that host original actin is packed to viral particle when SGIV is matured and finally released from the host cell. Actin may be assembled in the viral surface when virus is budding or it is specifically adhered to the viral envelope. This makes actin co-purified with the envelope proteins. Further studies indicated that the virus-infected cell turn round and the viral particles were co-located with the microfilament on the cell surface. This suggested actin was involved in viral release. When the SGIV was released from the cell, the virus obtained the cell membrane as its envelope, which was observed by electron microscopy. It was speculated that actin was specifically packed to the surface of the viral particle when SGIV was released. Together, actin played important roles when the viruses were released from the host cells.

Abstract:The structural composition of an ecosystem or biological community will change as a result of changes in the external environment, or the change in the manner of conversion between internal matter and energy. According to the study of the structure composition of ecosystem or biological community, this association can be used to analyze the internal and external state. The diversity index is a simple and feasible method to describe the composition of the ecosystem or biological community, and has been widely used in ecology. In order to study and understand the structure changes of fishery community structure and marine ecosystem in time and space, this paper, based on the survey data of four-quarter fixed-point bottom trawl in 2000, using the Shannon-Wiener, Margalef and Pielou indices which were commonly used in marine ecology researches, adopted the clustering analysis method and the spatial projection method to describe and summarize the distribution and variation of seasonal fishery biodiversity in the middle and north of the East China Sea and the southern part of the Yellow Sea, and discussed the possible causes of seasonal variation in the number and weight of organisms, and analyzed the association between diversity and biomass weight and quantity. The results showed that the sites in each season could be divided into three groups with high, middle and low diversity. The distribution of each group was in the shape of point, line and block. The combination of groups is analogous to a “sandwich” structure with the center, interlayer and outer layer corresponding to high, medium and low diversity. The distribution of the “sandwich” structure in each season may be related to the physiological cycle migration of fishery resources. The center waters of the structure may correspond to the main range of most fishery biological migration. For example, the centers of four “sandwich” structures in spring correspond to the spawning grounds for Pseudosciaena polyactis, Larimichthys crocea, Pampus argenteus, Setipinna taty, Thamnaconus septemtrionalis, Scomber japonicus, Auxis rochei, etc.. The center of “sandwich” structures in summer, autumn and winter may correspond to the main feeding, fostering and overwintering grounds of fishery organisms. There were waters in all seasons with high and low diversity groups connected directly, and the diversities showed the spatially skipped-changing. The resource biomass of these waters was generally relatively low. In the waters with low total resources, species diversity will be high when the species is relatively balanced, and once a species of biomass is slightly increased it may lead to drastic fluctuations in diversity. It was also found that these waters are generally adjacent to the relatively high biomass waters, and the range of the waters was negatively related to the absolute biomass of the relative high biomass waters. It might be related to the aggregation degree of some dominant species. The dominant species with higher biomass had higher aggregation degree, and the aggregation range and influence were relatively small. The smaller the influence sphere of the dominant species, the smaller the range of fluctuation of the diversity of the surrounding low-biomass samples. On the contrary, the dominant species with low aggregation degree, but its influence sphere is relatively large, and the range of fluctuation of the diversity of the surrounding low-biomass samples is large. The average weight and number of species in spring and winter are consistent, but not in summer and autumn. This may be related to different life cycle processes such as spawning, growth and recruitment. The fish body of the main fishery resources in each season is a relative standard, and number of relatively large or small individuals is relatively few. Non-standard body size only occurs in the summer and autumn, which might be due to the gradual increasing of the recruitment of fishing populations. A relatively small number of recruitment comes from some earlier spawning groups in summer, while main of the recruitment of the year comes in the fall. As a result of recruiting, the lean body appears in the highly diverse groups of summer and autumn. The overweight body in the middle and high diversity groups of summer might be because of the non-spawning broodstocks, whose body was always fat to ensure the next generation with enough nutrition. They also might include a small number of delayed spawning, or skipped-spawning fish in the stage of self-absorption, which were always with fat body. Regardless of weight or mantissa, the cases that diversity index decreased with the increase of biomass were more than the cases that diversity index increased with the increase of biomass. Most of the increase in biomass was not because of the increase in the number of species, but was likely to be due to the increase of biomass of very few dominant species, resulting in a decrease in the homogeneity of species and a decline in biodiversity. The positive association of diversity indices with mantissa was significantly higher than the positive relationship with weight, probably due to the increase in the number of organisms in most cases were due to the increase in the number of species resulting in higher diversity, while the increase of weight was mostly because the dominant species continued to expand, leading to the decrease of diversity.

Abstract:The microeukaryotic community structure and response to indoor simulated bioremediation by Nereis succinea of mudflat sediments in Jimei, Xiamen, was investigated by PCR-DGGE. The results indicated that the microeukaryotes in mudflat sediments of Jimei were mainly divided into four groups: Metazoa (including 6 phyla: Gnathostomulida, Annelida, Nematoda, Arthropoda, Mollusca and Gastrotricha), Cercozoa, Bacillariophyta and Alveolata (including Pyrrophyta and Ciliophora). The dominant group was Ciliophora, and the subdominant group was Nematoda. Peridinium quinquecorne (belonging to Pyrrophyta) was the dominant species. Cluster analysis of DGGE profiles indicated that nereids bioturbation had influenced the microeukaryotic community, and the treatment samples with nereids clustered together and separated from the control samples without N. succinea. More Nematoda were detected in treatment samples, which probably indicated that the nereid bioturbation stimulated the growth of Nematoda.

Abstract:Sedimentary organic matter (SOM) in seaweed beds provides an important material foundation for implementing seaweed bed ecosystem services. In this study, SOM samples were collected from the seaweed bed in northern Gouqi Island during the death period in July 2014, growth period in October 2014, and bloom period in May 2015, in accordance with three macroalgal life history stages: germinate and grow, mature and bloom, and decay and die. The sources and variations of the SOM were determined by carbon and nitrogen stable isotope analysis using the molar carbon-to-nitrogen (C/N) ratio and stable isotope composition (δ¹³C and δ¹⁵N) as indicators. The results showed the following. 1) The molar C/N ratios of the SOM varied in the ranges of 5.9–6.6, 6.0–6.9, and 5.4–6.2 in July, October, and the following May, respectively, indicating a typical marine source of SOM from the seaweed bed. 2) The δ¹³C values of the SOM were significantly different at the various water depths in July (–20.3‰ to –17.6‰); however, no significant changes were found in October (–22.3‰ to –21.7‰) or in May of the following year (–21.4‰ to –21.0‰). 3) The δ¹³C values of the SOM showed temporal variations, whereas spatial variations with water depth were found in July. 4) According to the relations among the δ¹³C, δ¹⁵N, and C/N, the SOM was mainly derived from the mixed contribution of phytoplankton and macroalgae in July, and it was attributed to the contribution of phytoplankton in October and the following May. 5) In July, macroalgae, on average, contributed up to 53.71% of the SOM from the seaweed bed, as estimated by the carbon stable isotope mass-balance mixing model. 6) The proportion of macroalgal detritus in the SOM was significantly affected by waves, among the various hydrodynamic factors in the marine environment.

Abstract:In order to investigate the growth performance and meat quality characteristics of I. punctatus cultured under traditional pond (TP), high density recirculating aquaculture system (HD-RAS) and cement pond (CP), the growth performance, nutritional composition, colour, water-holding capacity and texture of muscle from I. punctatus selected randomly were evaluated. The results showed that the weight gain rate and specific-growth rate between TP and HD-RAS groups had no significant difference, but higher than those of CP group which had the highest ratio of liver-somatic index (2.35%±0.22%). In comparison with TP group, the samples from HD-RAS and CP groups exhibited lower content of crude fat but higher content of crude protein and ash. The highest values of lightness (L*) (58.18±3.56) and redness (a*) (6.05±1.08) of HD-RAS group were obtained, and the lowest (48.15±6.04 and 4.81±0.84, respectively) were CP group. TP group exhibited lowest cooked rate, highest centrifugal loss, drip loss and liquid loss. Meanwhile, the difference between HD-RAS and CP groups was not statistically significant. The hardness, chewiness and springiness of HD-RAS and CP groups enhanced significantly compared with those of TP group. Additionally, no significant difference in cohesiveness and resilience was observed among the three groups. Given the results, the cement pond aquaculture mode resulted in a slower growth of I. punctatus. Compared to traditional aquaculture mode, the high density recirculating aquaculture system had no negative effect on the growth performance. Besides, the I. punctatus muscle from high density recirculating aquaculture pond exhibiting higher water-holding ability and better textural properties had characteristics of higher content of protein and lower content of fat.

Abstract:In the 12th Stockholm Convention, DDTs is one of the nine organic chlorine pesticides, which were proposed to be controlled as persistent organic pollutants (POPs), because of its harmful effects to the environment and the ecosystem. In China, a large amounts of DDTs have been used in the past few years, and it still can be generally detected in the environment although it was banned for using in agriculture in 1983. Many studies showed that fish consumption is a significant route for human exposure to POPs in the world. China is the largest fishery producer in the world with nearly 60 million metric tons in 2015, accounting for 70.0% of the total global fishery production. Recent study showed that residues of the DDTs have been widely identified and reported in some aquaculture fishes in China, especially in Trachinotus ovatus. To determine the bioaccumulation and the potential input sources of DDTs to cage farmed T. ovatus, samples of seed,feeds, adult fish, seawater and the sediments were collected at the beginning, medium and the end of aquaculture practice. DDTs were detected in all samples analyzed, with mean concentrations (±standard deviations) at (3.15±0.42) μg/kg wet weight in seed, (4.49±0.39) μg/kg wet weight in adult fish, (3.95±0.33) μg/kg dry weight in fish feeds, (3.76±0.43) ng/L in cage water and (4.34±1.18) μg/kg dry weight in sediment. The concentration of DDTs in the fish increased during the culture period and significantly higher when harvesting compared to the beginning and the medium, but well below the 0.5 mg/kg wet weight of national standards for food safety level. In addition, only ο,ρ’-DDT, ρ,ρ’-DDD and ρ,ρ’-DDT were detected in the sediments, but those three and ρ,ρ’-DDE were detected in the seeds, fish feeds and seawater. ο,ρ’-DDT and ρ,ρ’-DDT were the major constituents in all samples, with respectively average percentage at 42.09% and 37.07% in fish, 44.85% and 34.62% in fish feeds, 40.91% and 37.99% in cage water, 33.03% and 51.34% in sediment. Finally, statistical analyses suggested that fish feed, as well as pond water at a lesser degree, may have been the major source of DDTs in cage farmed fish of T. ovatus. In order to ensure the quality and safety of T. ovatus, we should focus on strengthening the control and management of toxic and harmful substances in the feed.

Abstract:In order to estimate and compare the genetic diversity and population structure between Abbottina rivularis and Hemiculter leucisculus in the Yellow River and Weihe River in Henan province, we used cytb sequences to estimate population genetic parameters and tested for demographic fluctuations. Our results showed that the population polymorphism of the two species was low. The results from phylogenetic tree, as well as haplotype network structure, showed that A. rivularis and H. leucisculus had three distinct lineages, however, there was no phylogeographic structure. The gene flow with moderate to low among populations explained that the two species had lower genetic diversity and distinct population differentiation. Then we analyzed the Demographic History of A. rivularis and H. leucisculus. Bayesian skyline plot revealed that the stock of the two species declined dramatically 0.019 and 0.026 million years ago, respectively. In view of the population polymorphism, population differentiation and demographic history, we concluded that the genetic diversity of A. rivularis and H. leucisculus was low in this study, and it was necessary to strengthen the protection of their resources.

Abstract:An experiment was carried out to evaluate effects of food concentration on the development, survival, reproduction of a calanoid copepod (Pseudodiaptomus dubia), in which the population life table was formed at different food concentration. The animals were fed with Chaetoceros muelleri as food designated with five food concentrations, 0.5×10⁵, 3×10⁵, 6×10⁵, 12×10⁵ and 17×10⁵ cells/mL, respectively. The results showed that different concentrations of C. muelleri had significant effects on the development, survival and reproduction of P. dubia. When the food concentration was 3×10⁵ – 6×10⁵ cells/mL, the development time, growth rate and hatching rate of P. dubia was 174–192 h, 0.6–0.64 μg C/d, and 464.2–608.2 neonates per female, respectively, which were significantly higher than those of the lowest concentration (0.5×10⁵ cells/mL) and the highest concentration (17×10⁵ cells/mL). The survival and lifespan decreased with the increase of food concentration. The survival of P. dubia reached up to 80% when the food concentration ranged from 0.5×10⁵ cells/mL to 6×10⁵ cells/mL, which were significantly higher than that of the 12×10⁵ and 17×10⁵ cells/mL. When the food concentration was 3×10⁵ – 6×10⁵ cells/mL, the intrinsic growth rate of P. dubia was 0.237/d and 28%–32% higher than that of 0.5×10⁵ and 17×10⁵ cells/mL. Therefore, putting too much or too little food would be disadvantageous to the population growth of P. dubia. Therefore, the most favourable food concentration for P. dubia would range from 3×10⁵ to 6×10⁵ cells/mL.

Abstract:Sipunculus nudus resources have been seriously damaged in the recent years due to overfishing and habitat destruction. Protecting natural resources of S. nudus has become more and more urgent. In this paper, genetic structure and population differentiation of S. nudus from 6 localities along the coasts of China were analyzed based on sequences of mitochondrial cytochrome b gene. Complete mitochondrial cytb sequences from 203 individuals of S. nudus were analyzed, 299 polymorphic sites and 128 haplotypes were identified and the nucleotide diversity and haplotypes diversity were 0.0488 and 0.9773, respectively. The variation among populations (accounting for 88.4%) was the main source of variation. According to differentiation index (F_st) in populations of S. nudus, the 5 populations in the south of Yantai showed no significant differences or low differences, with F_st<0.15. There were high differences between Yantai and other 5 populations, with F_st>0.15. Fu’s Fs and Tajima’s D were negative. Figures of mismatch distribution were unimodal. Haplotype network was radial structure centering on main haplotype. NJ phylogenetic tree of S. nudus based on 203 sequences of cytb of mtDNA revealed that these 6 populations were divided into 2 clades, one clade was Yantai population and the other clade included the rest 5 populations in the south of Yantai. All these results revealed that S. nudus population had experienced a large-scale population expansion in history, and the relatively low genetic diversity of S. nudus now suggested that the ability of S. nudus to adapt to environmental changes was poor and some measures should be taken to protect S. nudus resources. Phylogenetic tree suggested Yantai population was distinct from the other 5 populations, but whether Yantai population has become a cryptic species still needs further research.

Abstract:To figure out the nutrient cycling process and energy conversion efficiency of major biogenic elements in grass carp (Ctenopharyngodon idella) poly-culture ponds, this study investigated the potential effects of two different foodstuff sources (Sudan grass S. Sudanense, and formula feed) on the plankton community structure, and C/N trophic shift in grass carp poly-culture ponds using analytical techniques of stable isotope (δ¹³C and δ¹⁵N) and C/N ratio. Our results showed that two feeding modes yielded no statistically significant impact on the community structure of plankton, but the feeding mode with Sudan grass helped promote the plankton growth in the water column. In the ponds fed with Sudan grass, Sudan grass contributed 84% and 6.8% of energy to herbivorous and filter-feeding fishes (silver carp H. michthysmolitrix and bighead carp A. nobilis)), respectively. Moreover, Sudan grass contributed 7.4% of energy to particulate organic matter. In the ponds fed with artificial feed, herbivorous fish derived 70.4% of energy source from formula feed. Formula feed contributed 5.1%, 8.1% and 12% of energy source to bighead carp, POM and sediment, respectively. Our findings suggested that, first of all, the carbon and nitrogen elements of two foodstuff sources were utilized by herbivorous fish (grass carp and blunt-snout bream M. amblycephala), and then transferred the nutrients to filter-feeding fishes through the pathways of plankton, residual feeds and fish feces. Ultimately, the biogenic elements were dedicated to the sediment. In contrast with formula feed, the nutrient of Sudan grass could be more utilized by cultured fish than that deposited in the sediment. The trophic transfer was slower in ponds fed by Sudan grass than that in ponds fed by formula feed. Energy transfer of cultured fish was extremely relevant to foodstuff sources. In particular, the conversion efficiency in Sudan grass ponds was higher than that in formula feed ponds.

Abstract:In order to study the effects of nitrite nitrogen stress on blood biochemical indictors and HSP70 mRNA expression level of Aristichthys nobilis [initial average weight (180.05±0.092) g], 170 individuals of A. nobilis were exposed to water body with nitrite nitrogen concentration of 48.634 mg/L for 96 hours, and then a 96-hour recovery experiment was carried out. Blood and tissues of gill, head kidney, intestines and spleen were sampled at 0, 6, 12, 24, 48, 72, 96 h after stress, and at 12, 24, 48, 72, 96 h after recovery. For the stress and recovery experiment process, the results showed serum cortisol and ALT activity significantly increased first, after being stressed for 6 h. Thereafter, serum GLU presented significant increase at 12 h. Whereafter, serum CHOL, TP and TG decreased significantly and T3, AST increased significantly, while serum LDL and HDL decreased significantly at 72 h. For the recovery experiment, A. nobilis were recovered from nitrite nitrogen stress after 96 h. The HSP70 mRNA expression of different tissues showed that head kidney presented the fastest response to nitrite nitrogen stress, then gill, intestine and spleen. For recovering 96 h, HSP70 mRNA expression of head kidney, intestine and spleen returned to normal. The result suggested that nitrite nitrogen affected the protein metabolism, lipid metabolism and glycometabolism of A. nobilis, and also influenced the HSP70 mRNA expression of different tissues. A. nobilis showed rapid response to stress of high concentrations of water nitrite nitrogen after 6 h, so as to regulate physiological metabolism, and improve protection from stress injury and damage.

Abstract:An 8-week feeding trial was conducted to evaluate the potential of fish meal replacement with corn gluten meal (CGM) in diets for golden pompano (Trachinotus ovatus). A 2×3 layout was used. A basal diet (C) was formulated to contain 250 g/kg fish meal. In the test diets, 20, 40 and 60% of the fish meal in the basal diet was respectively replaced by either CGM (R) or γ-ray irradiated CGM (IR). The six test diets were abbreviated as R20, R40, R60, IR20, IR40 and IR60 (CGM was used as a fish meal substitute in diets R20, R40 and R60, and γ-ray irradiated CGM was used as a fish meal substitute in diets IR20, IR40 and IR60). All the diets were formulated at equal protein and lipid levels. Initial body weight of fish was (31.9±0.2) g. The results showed that weight gain, feed intake, feed conversion ratio (FCR), nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE) and body content of phosphorus were significantly affected by fish meal replacement level, while body phosphorus content was affected by the type of CGM used. Feed intake and weight gain decreased with increasing fish meal replacement level, regardless of CGM or γ-ray irradiated CGM as a fish meal substitute. At the same fish meal replacement level, no significant differences were found in the feed intake, weight gain, FCR, NRE, PRE, condition factor, hepatosomatic index and body composition (moisture, crude protein, crude lipid and ash) between fish fed the diets with fish meal replaced by CGM and γ-ray irradiated CGM. No significant differences were found in feed intake, weight gain, FCR and NRE between fish fed diets C and R20, suggesting that dietary fish meal level for T. ovatus can be reduced to 200 g/kg when CGM was used as a fish meal substitute. This study reveals that γ-ray irradiation could not improve CGM as a fish meal substitute in T. ovatus diet.