Economic analysis of tiger grouper <Emphasis Type="Italic">Epinephelus fuscoguttatus</Emphasis> and humpback grouper <Emphasis Type="Italic">Cromileptes altivelis</Emphasis> commercial cage culture in Indonesia

This study presents an economic analysis of tiger and humpback grouper at different production scales in Indonesia. The results highlight the non-viability of small-scale tiger grouper farming, with a 5-year projected negative cumulative cash flow of −IDR 18,102,650.00 and a negative net present value (NPV) of −IDR 22,059,576.28. An increased production scale of tiger grouper highlights a marginal viability for medium-scale farms (with a 5-year projected cumulative cash flow of IDR 198,320,673.00, a positive NPV of IDR 105,578,440.42; a benefit cost ratio of 1.25; an internal rate of return (IRR) of 88% and a payback period of 0.99 years), and an economically viable large-scale cage culture (with a 5-year projected cumulative cash of IDR 707,746,923.00; a NPV of IDR 406,801,749.07; a benefit cost ratio of 1.33; an internal rate of return of 157%; and a payback period of 0.57 years). The economic analysis of humpback grouper at different production scales highlighted a positive cumulative cash and NPV, a benefit cost ratio over 2, an internal rate of return over 300% and a payback period <1 year. A sensitivity analysis revealed that increased survival rate up to 80% would increase cumulative cash and NPV of small-scale tiger grouper cage culture. Additionally, improved profitability performance was associated with decreasing major production costs, increasing production and price of the product.     

Growth and survival of grouper <Emphasis Type="Italic">Epinephelus</Emphasis><Emphasis Type="Italic">coioides</Emphasis> (Hamilton) larvae fed free-living nematode <Emphasis Type="Italic">Panagrellus redivivus</Emphasis> at first feeding

The free-living nematode, Panagrellus redivivus, was tested as live food for grouper Epinephelus coioides larvae during the first feeding stage. A series of experiments were conducted to determine the acceptability of the free-living nematodes in grouper larvae at first feeding, the optimum nematode density and the response of the larvae to nutritionally enriched nematode. All experiments were conducted in 200-L conical tanks filled with 150-L filtered seawater and stocked at 15 larvae L⁻¹. Duration of feeding experiments was up to day 21 (experiment 1) and 14 days (experiment 2 and 3). Brachionus plicatilis and Artemia (experiment 1) and Brachionus plicatilis alone (experiment 2 & 3) was used as the control treatment. Observations indicated that the grouper larvae readily fed on free-living nematodes as early as 3 days posthatching, the start of exogenous feeding. Optimum feeding density for the larvae was 75 nematodes ml⁻¹. The enrichment of cod liver oil or sunflower oil influenced the total lipids and n-3 highly unsaturated fatty acids of P. redivivus, which in turn influenced those of the grouper larvae, however, growth and survival of the larvae were not affected (P > 0.05). The results from this investigation showed that the nematode, P. redivivus, can be used as first live food for grouper larvae from the onset of exogenous feeding until they could feed on Artemia nauplii.     

Screening of enzyme activity for assessing the condition of larvae in the seven-band grouper <Emphasis Type="Italic">Epinephelus septemfasciatus</Emphasis> and devil stinger <Emphasis Type="Italic">Inimicus japonicus</Emphasis>

We conducted screening tests to determine whether enzyme activity is a suitable biomarker for assessing the physiological condition of marine fish larvae. The rearing experiments consisted of three trials, of which two were conducted using the seven-band grouper Epinephelus septemfasciatus for a period of 5 days after hatching (DAH), and one was conducted using the devil stinger Inimicus japonicus for 10 DAH. The trials were conducted under three different rearing-tank environments (shallow tank, intermediate tank, deep tank) in a water volume of 100 l and an aeration rate of 50 ml/min. We determined survival, surface death, growth, and enzyme activities (trypsin, esterase, and alkaline phosphatase). The highest survival rates and lowest surface deaths in both species occurred among the larvae grown in the deep tank. There was a significant and negative correlation between survival at 5 DAH and alkaline phosphatase activity at 0 DAH in the seven-band grouper. The same correlation was found between survival at 10 DAH and trypsin and alkaline phosphatase activity at 1 DAH in the devil stinger. Based on these results, we conclude that the activity of a specific enzyme is a candidate for assessing the physiological condition of marine fish larvae.     

Dietary polysaccharide from <Emphasis Type="Italic">Angelica sinensis</Emphasis> enhanced cellular defence responses and disease resistance of grouper <Emphasis Type="Italic">Epinephelus malabaricus</Emphasis>

The purpose of this study was to determine the effect of Angelica sinensis polysaccharide (ASP) supplemented in diet on the innate cellular immune response and disease resistance in grouper, Epinephelus malabaricus. Fish were fed diets containing different doses of ASP (0, 500 and 3,000 mg kg⁻¹ diet) for 12 weeks. After 12 week feeding, the respiratory burst activity, phagocytic activity, and leukocytes proliferation in head kidney were assayed. The functional immunity in terms of cumulative mortality was also assessed by a challenge with live Edwardsiella tarda. Results showed that the respiratory burst activities in ASP-supplemented groups were increased significantly. The respiratory burst index was the highest in fish-fed 3000 mg kg⁻¹ diet and the lowest in control. The phagocytic activities in ASP-supplemented groups were significantly higher than that of control. No significant difference in phagocytic activity was observed between ASP-supplemented groups. ASP stimulated the head kidney leukocytes proliferation significantly, despite the absence of lipopolysaccharide (LPS) or not. The cumulative mortalities of fish fed with 3000 mg ASP kg⁻¹ diet were significantly lower than those fed with 500 mg ASP kg⁻¹ diet and control diet after 96 h of challenge. In conclusion, dietary ASP enhanced some cellular immune parameters and disease resistance against E. tarda in grouper.     

Morphological development of larval and juvenile blacktip grouper, <Emphasis Type="Italic">Epinephelus fasciatus</Emphasis>

The morphological development of larval and juvenile blacktip grouper, Epinephelus fasciatus, was examined using a hatchery-reared series. By about 5 mm body length (BL), the larvae developed characteristic pigmentation patterns of groupers, such as melanophores on the dorsal part of the gut, on the tips of the second-dorsal and pelvic fin spines, and on the midpoint of the tail to form a cluster. In addition, characteristic spines of groupers, such as spinelets on the second-dorsal and pelvic fin spines, and the preopercular angle spine developed by about 6 mm BL. The notochord end was in the process of flexion in larvae of 6–7 mm BL, by when major melanophores, spines, and jaw teeth started to appear. After the fin ray counts attained the adult complement at about 14 mm BL, somewhat densely pigmented bands started to appear on the body. The fish had the five distinct transverse bands and attained adult-like attire at about 40 mm BL when the major head spines disappeared and body parts in relation to BL became stable.     

Transpositional feeding rhythm of loach <Emphasis Type="Italic">Misgurnus anguillicaudatus</Emphasis> from larvae to juveniles and its ontogenesis under artificial rearing conditions

The diel feeding rhythm and ontogenesis during early life stage of loach Misgurnus anguillicaudatus were investigated under experimental conditions (light: L 06:00–18:00, D 18:00–06:00 h). Morphological and behavioral developments of loach from newly hatched to 40 days after hatching were observed. Larvae were able to prey on daphnia 3–4 days after hatching at 23 ± 0.5°C. As the larvae grew, they showed an increasing feeding capacity and a distinct feeding rhythm. Feeding intensity and incidence for day-4 larvae were highest at 10:00 and 16:00 h. The highest levels of feeding intensity for day-12 larvae occurred at 08:00, 12:00, and 18:00 h as did feeding incidence. By day 20, when the larvae metamorphosed, the highest levels of feeding intensity occurred at 06:00, 18:00, and 24:00 h and were concurrent with the highest feeding incidence. After metamorphosis, feeding capacity had again increased considerably and, in contrast to the earlier stages before day 20, feeding intensity for day-30 juveniles peaked at 05:00 and 20:00 h, about 1–2 h after the maximum feeding incidence. The feeding rhythm of loach juveniles at day 40 was almost the same as the day-30 juveniles. The estimated maximum daily feeding rates were 43.1%, 33.4%, 19.0%, 12.8%, and 5.8% of body weight on days 4, 12, 20, 30, and 40, respectively. Thus, loach was found to have different feeding rhythms in the pre- and post-metamorphosis stages, with the highest feeding activity in daytime during the larval planktonic stage before metamorphosis, and intensely nocturnal feeding behavior during the juvenile benthic stage after metamorphosis.     

Pyridoxine deficiency of grouper, <Emphasis Type="Italic">Epinephelus coioides</Emphasis>: physiological and biochemical alteration

Pyridoxine is essential for animals. The purpose of this study was to investigate the pyridoxine deficiency symptoms and the fit dose of pyridoxine to keep normal physiological function in grouper, Epinephelus coioides. Graded levels of pyridoxine (0, 1, 2, 4, 8, 16, 32 mg pyridoxine kg⁻¹ diet) were fed to grouper juveniles (14.83±0.31 g) for 8 weeks, and then some physiological and biochemical parameters were measured. Pyridoxine deficiency symptoms such as anorexia, poor survival, convulsion, helically swimming and hyperirritability were observed in fish fed the pyridoxine-deficient diet, and these fish also showed low whole blood haemoglobin level, liver glutamic-pyruvic transaminase (GPT) and superoxide dismutase (SOD) activities. Slight symptoms of pyridoxine deficiency also appeared among fish fed the diet with very low dose (1 mg pyridoxine kg⁻¹ diet) of pyridoxine in 6 weeks. Broken-line regression analysis showed that the optimal pyridoxine levels for these fish to keep normal survival, whole blood haemoglobin level, liver GPT and SOD activities were approximately 1.75, 1.87, 2.22 and 2.05 mg kg⁻¹, respectively.     

Effect of shelter acclimation on the post-release survival of hatchery-reared black-spot tuskfish <Emphasis Type="Italic">Choerodon schoenleinii</Emphasis>: laboratory experiments using the reef-resident predator white-streaked grouper <Emphasis Type="Italic">Epinephelus ongus</Emphasis>

A critical component of many releasing projects is the identification and subsequent implementation of optimal release strategies that can decrease post-release predation mortalities. We performed laboratory experiments to investigate whether acclimation to shelters affects the post-release survival of hatchery-reared black-spot tuskfish Choerodon schoenleinii in the presence of a reef-resident predator, the white-streaked grouper Epinephelus ongus. Tuskfish were exposed to groupers under three different experimental conditions/treatments: (1) acclimation of fish to shelters prior to their exposure to groupers; (2) no acclimation of fish to shelters, but with shelters available during their exposure to groupers; (3) fish not acclimated to shelters and no shelters available during their exposure to groupers. Tuskfish that were acclimated to shelters utilized shelters more frequently than did non-acclimated fish, and the survival rate of acclimated fish was higher than those of fish in the other treatments. These results suggest that pre-release acclimation to shelters improves the post-release survival of hatchery-reared black-spot tuskfish.     

Nucleic acids digestion by enzymes in the stomach of snakehead (<Emphasis Type="Italic">Channa argus</Emphasis>) and banded grouper (<Emphasis Type="Italic">Epinephelus awoara</Emphasis>)

Dietary nucleic acids (NAs) were important nutrients. However, the digestion of NAs in stomach has not been studied. In this study, the digestion of NAs by enzymes from fish stomach was investigated. The snakehead pepsins (SP) which were the main enzymes in stomach were extracted and purified. The purity of SP was evaluated by SDS-PAGE and HPLC. The snakehead pepsin 2 (SP2) which was the main component in the extracts was used for investigating the protein and NAs digestion activity. SP2 could digest NAs, including λ DNA and salmon sperm DNA. Interestingly, the digestion could be inhibited by treatment of alkaline solution at pH 8.0 and pepstatin A, and the digestion could happen either in the presence or absence of hemoglobin (Hb) and BSA as the protein substrates. Similarly, the stomach enzymes of banded grouper also showed the NAs digestion activity. NAs could be digested by the stomach enzymes of snakehead and banded grouper. It may be helpful for understanding both animal nutrition and NAs metabolic pathway.     

Establishment and characterization of a kidney cell line from kelp grouper <Emphasis Type="Italic">Epinephelus moara</Emphasis>

A novel cell line, Epinephelus moara kidney cell line (EMK), was established from kidneys of kelp grouper E. moara. Cells were cultured at 24 °C in Leibovitz’s L-15 medium (L15) supplemented with antibiotics, basic fibroblast growth factor (bFGF), foetal bovine serum (FBS) and 2-mercaptoethanol (2-ME). EMK cells, fibroblastic in morphology, proliferated to 100% confluency in 3–4 days and were subcultured for over 50 passages. The cells could grow from 18 to 30 °C, with optimal growth at 24 °C. Chromosome analysis indicated that the modal chromosome number was 48 in the cells at passage 42. Green fluorescent signals could be observed in EMK cells when the cells were transfected with pEGFP-N3 plasmid. Moreover, a significant cytopathic effect (CPE) was observed in the cells after infection with Singapore grouper iridovirus (SGIV) or nervous necrosis virus (NNV), and viral replication was confirmed by quantitative real-time PCR (qPCR). These results suggested the potential of the EMK cell line for studies of transgene and pathogenesis of SGIV and NNV.     

Enhancement of survival and metamorphosis rates of <Emphasis Type="Italic">Penaeus monodon</Emphasis> larvae by feeding with the diatom <Emphasis Type="Italic">Thalassiosira weissflogii</Emphasis>

The purpose of this study was to compare the performance of two species of diatoms, Thalassiosira weissflogii and Chaetoceros gracilis, in the larviculture of the black tiger shrimp Penaeus monodon. Shrimp larvae were fed with either C. gracilis, T. weissflogii, or a combination of the two species of diatoms. The larvae fed solely with T. weissflogii or a combination of the two types of diatom had significantly higher survival rates and faster metamorphosis than those fed solely with C. gracilis. The numbers of diatom cells consumed by larvae during 3-h periods were determined, revealing that larvae consumed significantly higher numbers of C. gracilis than T. weissflogii. However, when the protein, total fatty acid, and polyunsaturated fatty acid content of the two species of diatom are compared, significantly higher amounts of each are found in T. weissflogii. Converting the number of diatom cells consumed into equivalent protein, total fatty acid, eicosopentaenoic acid, and decosahexaenoic acid reveals that larvae fed with T. weissflogii received significantly higher amounts of all the nutrients, compared to those consuming C. gracilis. The results showed an advantage of feeding T. weissflogii to C. gracilis in enhancing survival and metamorphosis in P. monodon larvae.     

Influence of the dietary inclusion of <Emphasis Type="Italic">Gracilaria cornea</Emphasis> and <Emphasis Type="Italic">Ulva rigida</Emphasis> on the biodiversity of the intestinal microbiota of <Emphasis Type="Italic">Sparus aurata</Emphasis> juveniles

Partial substitutions of fish meal by 5, 15, or 25 % of Gracilaria cornea or Ulva rigida in experimental diets were evaluated to study their effects on biodiversity of intestinal microbiota composition in gilthead seabream (Sparus aurata) juveniles. The diets were offered to duplicate groups of 15 juvenile fish (14.0 ± 0.5 g) for 70 days, and at the end of the experiment the intestinal microbiota from four specimens of each treatment was analysed by denaturing gel gradient electrophoresis. Results showed that the substitution of fish meal by algae meal induced important modifications in the intestinal microbiota community, as a big reduction of the biodiversity when the highest percentage (25 %) of U. rigida was included. On the contrary, an increase on the number of species was detected when a 15 % of algae was included. Various Lactobacillus delbrueckii subspecies were selectively stimulated when G. cornea was included in the feed, and other bacterial species, such as those included in the Vibrio genus, were reduced.     

<Emphasis Type="Italic">Curcuma longa</Emphasis> as additive in the diet for <Emphasis Type="Italic">Astyanax aff. bimaculatus</Emphasis>

The aim of the present study was to evaluate the effect of turmeric (Curcuma longa) as additive in the diet for Astyanax aff. bimaculatus. Fish (0.83 ± 0.04 g) were fed, for 60 days, with six diets containing 0.0, 20.0, 40.0, 60.0, 80.0, and 100.0 g turmeric kg^?1 feed. There was an increasing linear effect of turmeric on the thickness of the muscular layer, and height and width of the folds of the intestine. In the liver, a quadratic effect was observed of turmeric on the percentage of hepatocyte cytoplasm and a decreasing linear effect on the percentage of sinusoid capillaries. A quadratic effect was also observed of turmeric on the liver glycogen. There was no effect of turmeric on the antioxidant activity in the liver, carcass composition or productive performance of the fish. Thus, we concluded that Curcuma longa has trophic effects on the epithelium and the muscular layer of the intestine of A. aff. bimaculatus. Additionally, low levels of Curcuma longa cause increased deposition of liver glycogen and high levels cause reduction.     

Spatial learning-induced <Emphasis Type="Italic">egr</Emphasis>-<Emphasis Type="Italic">1</Emphasis> expression in telencephalon of gold fish <Emphasis Type="Italic">Carassius auratus</Emphasis>

The immediate-early gene (egr-1) expression was used to examine the neuron’s response in telencephalon of goldfish during spatial learning in small space. Fishes were pre-exposed in the experimental apparatus and trained to pick food from the tray in a rectangular-shaped arena. The apparatus was divided into identical compartments comprising three gates to provide different spatial tasks. After the fish learned to pass through the gate one, two more gates were introduced one by one. Fish made more number of attempts and took longer time (P < 0.05) to pass through the first gate than the gate two or three. This active learning induces the expression of egr-1 in telencephalon as established by western blot analysis. Subsequently, the fish learn quickly to cross the similar type of second and third gate and make fewer errors with a corresponding decline in the level of egr-1 expression. As the fish learned to pass through all the three gates, third gate was replaced by modified gate three. Interestingly, the level of egr-1 expression increased again, when the fish exhibit a high exploratory behavior to cross the modified gate three. The present study shows that egr-1 expression is induced in the telencephalon of goldfish while intensively acquiring geometric spatial information to pass through the gates.     

Remarkably high survival rates under dim light conditions in sutchi catfish <Emphasis Type="Italic">Pangasianodon hypophthalmus</Emphasis> larvae

The sutchi catfish Pangasianodon hypophthalmus is an important species for aquaculture in Southeast Asia. However, larvae typically have low survival rates due to their predilection for cannibalism during rearing. This study investigated larval feeding behavior and rearing conditions. The former experiments were performed to elucidate the role of sensory organs in feeding, and the latter experiments examined the effect of dim light on larval rearing and survival rates. Neither lighting conditions (light and dark) nor blocking of free neuromasts by streptomycin had significant effects on feeding behavior. Therefore, the feeding behavior of sutchi catfish larvae most likely depends on chemosensing rather than visual sensing. In the later experiments, larval rearing at 0.1 l× yielded significantly higher survival rates than other lighting conditions (0.00, 1, 10, 100 l×). Survival in the 0.1 l× group was almost three times higher than in the 100 l× group. Moreover, larvae reared under 0.1 l× showed steady growth. Therefore, it is concluded that 0.1 l× is the optimum light intensity for sutchi catfish larval rearing.