Fiberglass Tanks Research Articles

Larval Rearing of the Giant Trevally, Caranx ignobilis (Forsskål, 1775), Fed Live Food Combinations of Rotifers, Copepods and Artemia salina

The giant trevally, Caranx ignobilis, is a high value fish which has been studied for spawning in captivity and domestication in the Philippines in view of its aquaculture potential. Initial larval rearing of the species encountered mortality issues, and this study attempts to address the problem to improve their survival. Hatchery-bred C. ignobilis larvae were reared for 40 days in nine units of 100 L conical fiberglass tanks at a stocking density of 500 larvae.tank-1 under three feed treatments with different combinations of rotifers (Brachionus plicatilis), brine shrimp (Artemia) and copepods (Pseudodiaptomus spp.): T1- Brachionus plicatilis + Artemia, T2- Brachionus plicatilis + Pseudodiaptomus spp., and T3-Brachionus plicatilis + Pseudodiaptomus spp. + Artemia fed at 0800 h and 1600 h. The results showed that the inclusion of copepods in the feeding regimen had positive effects on survival. Survival rate was significantly higher (P < 0.05) in T2 (23.47 ± 3.18 %) than T1 (11.67 ± 1.90 %) but was not statistically different from T3 (14.37 ± 3.88 %). Length increment was significantly different (P < 0.05) among treatments but with no statistical difference in specific growth rate (P > 0.05). The erratic swimming behaviour leading to mortality associated with insufficient levels of highly unsaturated fatty acids in Artemia was not observed in T2, thus, validating the assumption that the feeding with copepods will increase survival during larval rearing. The use of copepods for C. ignobilis larviculture is seen to play an important role in the success of the seed production protocol for this species. However, a sustainable supply of copepods through appropriate mass propagation techniques must be ensured to achieve higher production of C. ignobilis seeds in the hatcheries.

Autochthonous probiotic bacteria improve intestinal pathology and histomorphology, expression of immune and growth-related genes and resistance against Vibrio alginolyticus in Asian seabass (Lates calcarifer).

The study isolated two strains of intestinal autochthonous bacteria Lactiplantibacillus plantarum1 (MH155966.1) (L1) and Lactiplantibacillus plantarum2 (MH105076.1) (L2) from the Choobdeh Abadan region. The aim of this study was to investigate the effects of different strains of probiotic bacteria on the growth performance, digestive enzyme activity, histopathologic and histomorphometric characterization of the intestine, expression of immune and growth related genes, and evaluate Lates calcarifer resistance against Vibrio alginolyticus. To achieve this, for each treatment 60 L. calcarifer juveniles (75 ± 12g) were randomly distributed in three fiberglass tanks (300L) and fed for 45 days. The treatments were established as Diet 1 (control diet); L1 (diet with Lb. plantarum isolated 1); L2 (diet with Lb. plantarum isolated 2) with a bacterial concentration of 1 × 109 CFU/g. Nine fish from each treatment were sampled and examined, after euthanasia. The fish were placed 2cm from the beginning of the intestine for microscopic sampling of villi height, villi width and thickness of the epithelium, with 3 treatments: The result showed differences in the mean values of total weight were found at the end of the experiment. After 45 days of culture, the fish fed with L1 had higher (P < 0.05) growth performance than the other treatment groups. But at the end of the trial, in L2, the digestive enzyme activities were higher (P < 0.05) than the other treatment groups. The fishes fed diets supplemented with the L2 group, like the digestive enzyme activities test, presented an increase in the thickness of the epithelium of the intestine, and villus height, and villus width were greatest in L2. Fish feeding with L1 and L2 probiotics induced higher transcription levels of interleukin-10 (IL-10), granulocyte-macrophage colony-forming cells (GMCFC), epidermal growth factor (EGF), and Transforming Growth Factor Beta (TGF-β) genes in the gut, which may correlate with better immune and hematological parameters in these groups. The results of the challenge test revealed that the percentage of survival was significantly higher in L1 (76.2%) and L2 (80.95%) treatments than in the control (P < 0.05). These results indicate that host-derived probiotics (Lb. plantarum) have significant potential as important probiotics to enhance nutrient utilization, Digestive enzymes, and metabolism by increasing the gut surface area of Lates calcarifer juveniles at 45 days of culture.

Impact of organic and nanoparticle-selenium fortified larval weaning diet on survival, growth, gastrointestinal, and (GPx) activity of European Sea Bass (Dicentrarchus labrax) Larvae

The study involved three groups of six broodstock with a 1:1 male-to-female ratio. They were injected with 13 µg/kg LHRHa to stimulate spawning. We fed the broodstock three diets: a control diet without selenium, a diet containing 0.3 mg of nano-selenium /kg (N-Se), and a diet containing 4 mg of organic selenium /kg (O-Se). The broodstock diet consisted of equal parts of dry feed (45% protein), sardines, and squid. After being laid, the eggs were obtained from the collection ponds at the General Authority for Fisheries Development's fish hatchery and incubated until hatching. The larvae were given a micro diet containing 51.7% crude protein and live food (Rotifer and Artemia). Rotifer density increased from 5/ml to 15/ml by day 22 dph, Artemia nauplii increased from 0.2 to 4 ind./ml, from 7 to 35 dph then decreased to 0 at 55 dph, and micro-diets increased from 100-200 µ at 16 dph to 200-400 µ at 23-40 dph to 300-500 µ at 55 dph, and 500-1000 µ until the experiment ended. Three different diets in three replicates were tested: A micro diet free of selenium as a control diet (C), A micro diet with 0.3 mg of nano selenium (N-Se) kg-1, and A micro diet supplemented with organic selenium 4 mg (O-Se). Each group was taken from the three Broodstock groups respectively. Sixteen days after hatching, the three experimental micro diets were introduced to the larvae and continued for 76 days post-hatch. Larvae (260,000 per tank) were placed in fiberglass tanks with 4 m3 of water at a temperature of 19±2°C for optimal conditions. The larvae fed the N-Se diet had significantly better survival rates (75.0 ± 1.2 %), final body weight (240.0 ± 5.8 mg), weight gain (239.00 ± 5.8 mg), average daily gain (3.98±0.1mg), total length (39.0±0.06 mm), specific growth rate (9.133±0.04 %/day), feed intake (471.67±0.01 mg), and better feed conversion ratio (1.97±0.01) than the other groups (P < 0.05). The group provided with N-Se also had the highest levels of glutathione peroxidase enzyme (GPx) content in the whole larval body, whereas the control diet without Se supplementation recorded the lowest value of (14.8 ± 0.1 U/mg protein). The number and length of folds in the stomach and esophagus of sea bass post-larvae fed on diets fortified with selenium in both forms, nanoparticles or organic, showed a significant (P < 0.05) enhancement on the larval gastrointestinal (GI) tract. Moreover, selenium has an anti-inflammatory action in sea bass post-larvae. This study concluded that using N-Se as an antioxidant supports the growth and survival of European seabass D. labrax, gastrointestinal development and antioxidant efficacy during critical weaning.

Enhancing Florida red tilapia aquaculture: biofloc optimization improves water quality, pathogen bacterial control, fish health, immune response, and organ histopathology across varied groundwater salinities.

Freshwater scarcity poses challenges to aquaculture worldwide, including countries like Egypt. In this study, we investigate the feasibility of integrating underground saline water (USW) with varying salinities into a Biofloc (BFT) system for desert mariculture of Florida red tilapia (FRT) and its impacts on water quality, fish performance and health. Four BFT treatments (C/N ratio = 15) were examined in triplicate using four salinity levels 0 ppt, 12 ppt, 24 ppt and 36 ppt, expressed as S0, S12, S24 and S36, respectively. For 75 days, a total of 12 fiberglass tanks (each 250L-1 water) were used to store FRT fry (average weight of 1.73 ± 0.01g/fish). The fish were fed an experimental diet (protein/fat = 30/5) and an additional carbon source of rice bran. The results revealed that group S12 showed better growth indicators, higher survival rate, lower FCR, and lower ammonia levels, while group S0 exhibited lower growth indicators (final weight, weight gain, and specific growth rate) than all groups. The serum kidney, liver, and antioxidant indices performed better in the S12 group. At 12 ppt, the immune-related parameter (IgM) increased by 22.5%, while the stress parameter (cortisol) decreased by 40.8% compared to the S0 group. The liver and intestinal histopathological results revealed that the S12 and S24 groups performed better. Pathogenic bacterial load counts favored the S24 group, which had the lowest number among the groups studied. The recommended salinity for FRT cultivation in USW and BFT is 19.94-20 ppt, determined by polynomial regression of FW and FCR.

Dietary Taurine Improves The Growth Performance, Health Status and Liver Histopathology of Meagre (Argyrosomus Regius) Fed A Reduced Fish Meal Diet

Abstract Research has focused on alternative plant materials or additives that can be used instead of fish meal due to limited stocks and increased feed prices, although it is important for carnivorous fish species. Taurine is a functional amino acid supplemented to low fish meal diets to improve the growth performance of fish. In this study, eight experimental diets with 0%, 0.5%, 1% and 2% ratios of taurine supplemented (T0, T0.5, T1 and T2) high (HFM) and low fish meal (LFM) diets were prepared (defined as HFMT0, HFMT0.5, HFMT1, HFMT2, LFMT0, LFMT0.5, LFMT1 and LFMT2). The experiment was carried out in twenty-four 400 L rectangular fiberglass tanks conducted in a marine water system, and fish (initial mean weight of 23.5 g) were stocked in each tank. The nutrition trial was carried out for 90 days with three replicates. Meagre fed with the HFMT1 diet had a higher final mean weight (FMW) and specific growth rate (SGR) than fish fed with HFMT0 and all LFM diets. Including taurine in all LFM diets also enhanced growth performance. The FMW and SGR of fish fed the LFMT0.5 diet were similar when compared to HFMT0 (P&gt;0.05) and increased compared to that of other LFM diets with taurine (P&lt;0.05). Meagre fed the LFM0.5 diet had a lower feed conversion rate (FCR) than those provided for all HFM diets, although there was no significant difference between treatments. Dietary taurine has decreased the hepatosomatic index (HSI), viscerosomatic index (VSI) and total ammonia-nitrogen excretion (TAN), irrespective of taurine and fish meal levels. Including dietary taurine at both fish meal levels enhances the number of red blood cells (RBC) and whole-body amino acids of meagre. The most remarkable conclusion of this study is the inclusion of taurine in low fish meal diets improved growth performance and profitability in meagre, and the level of 0.5% has been recommended.

Evaluation and economic analysis of fermented fish viscera silage in diets for tambaqui (Colossoma macropomum) and its effects on the physical quality of pellets, growth performance, health parameters.

The production of silage using fish viscera can be carried out with straightforward methods and permits the exploitation of nutrients that are usually discarded. This process fosters the concept of circular aquaculture. The aim of this study was to evaluate the inclusion of increasing levels of fish viscera silage (VS) on the physical quality of the feed pellets and their effects on their growth performance, health parameters and on economic indices when the experimental extruded feed was offered to tambaqui. A fermented fish VS produced in-house was included in increasing levels on a wet-basis in the formulation of five experimental diets (VS 0%, VS 5%; VS 10%; VS 15%and VS 20%). Juvenile tambaqui (~22.6 g) were stocked in fibreglass tanks of 700 L (n = 4; 21 fish per tank) with a recirculation system and the five experimental diets were attributed in a completely randomized design. The fish were fed with the experimental diets (to apparent satiation) for 13 weeks. At the end of the trial, no significant differences were observed for production performance. Fish fed with the highest inclusion level of VS presented the highest concentration of plasma cholesterol, but this was still within acceptable values for this species. The inclusion of fish VS in diets for juvenile tambaqui reduced the activity of the plasma ALT enzyme, confirming normal liver function. Extruded feed containing fish VS had a production cost of US$ 0.95 per kg, which does not significantly impact the economic indices. Up to 20% of fish VS can be included in the extruded feed formulation for juvenile tambaqui without impairing growth performance or affecting health parameters.

Enhancement of Growth Performance and Body Coloration Through The Inclusion of Torch Ginger Powder in The Feed of Red Tilapia (Oreochromis sp.)

Red tilapia (Oreochromis sp.) is a highly produced aquaculture fish among freshwater species. Coloration is an important factor in determining consumer preferences. Therefore, an 8-week experiment was conducted to enhance the growth performance and body coloration through the inclusion of torch ginger in the feed of red tilapia. Five experimental feeds were prepared from commercial feed (crude protein: 34%, crude lipid: 5%) containing torch ginger powder at 2.5, 5.0, 7.5, and 10% (T1, T2, T3, &amp; T4) inclusion levels while feeding without torch ginger act as a control (T0). Red tilapia (Initial body weight: 0.4±0.1g; Initial total length: 4.0±0.1cm) were distributed at stocking number 20 fish/tank into fiberglass tanks with a capacity of 80 L and triplicates for each treatment. The fish were fed with experimental feeds until satiation. The growth of fish was significantly higher (P&lt;0.05) when the fish fed with T1, T2, and T3 compared to control treatment T0. Moreover, the feed intake was significantly increased (P&lt;0.05) when the torch ginger powder was added to the experimental feeds. In addition, the FCR was significantly better (P&lt;0.05) when the fish fed on T1, T2, and T3 compared to T0. The inclusion of torch ginger powder in the feed did not significantly affect (P&lt;0.05) the body protein and lipids of the experimental fish. The increment of redness was significantly higher (P&lt;0.05) when the fish fed with T1, T2, T3, and T4 compared to T0. However, it showed a declining trend of redness when the inclusion of torch ginger increased to 5.0% and above. Thus, the present study suggested that the inclusion of torch ginger powder improved the performance and enhanced the body coloration of juvenile red tilapia. However, a further increase of torch ginger powder by more than 2.5% did not help in the enhancement of the body coloration.

Sublethal Concentrations of Cadmium and Lead: Effects on Hemato-Biochemical Parameters and Tissue Accumulation in Wallagu attu.

The exposure of fish to heavy metals can significantly impact physiological processes and potentially lead to adverse health effects. This study assesses the effects of exposure to Cd and Pb sublethal concentrations in water on Wallagu attu. A total of 48 fish with an average body weight of 145.5 ± 26g were distributed among three groups (control, Cd-treated, and Pb-treated) within 60L fiberglass tanks. They were exposed to30% sublethal concentrations of Cd and Pb for durations of 1, 15, and 30 days. Following this exposure, an assessment was conducted on metal bioaccumulation and hemato-biochemical responses. Results revealed a significantly (P < 0.05) higher concentration of heavy metals in the fish tissues of metals exposed groups than in the control. The concentration of Cd and Pb increases in fish tissues (kidney > gills > intestine) with exposure time. In most cases, the Pb-exposed group exhibited significantly (P < 0.05) higher concentrations of Pb in different tissues than the Cd-treated group. With extended exposure time, the activities of CAT and SOD show a significant decrease in both Cd and Pb-treated groups. However, the reduction in activities was more pronounced in the Cd-exposed group. On 15 and 30 days, the levels of red blood cells (RBC), hemoglobin (HB), hematocrit (HCT), and total protein (TP) decrease in groups exposed to Cd and Pb. The cortisol and glucose levels exhibit a more noticeable (P < 0.05) increase with prolonged exposure to Cd and Pb than the control group. On day 30, the survival rate decreased more in the Pb-exposed group. The findings of this study indicate that exposure to sublethal doses of Cd and Pb induces stress in Wallagu attu, resulting in rapid changes in specific hemato-biochemical parameters.

Ecological Insights, and Fin Fish Diversity in Carps Spawning Grounds: Case Studies from the Surma River and Tanguar Haor, Bangladesh.

This study aims to provide a thorough ecological understanding of fin fish diversity within carp spawning grounds in the Surma River and Tanguar haor. Over two spawning seasons, this research investigates ecological factors impacting fin fish diversity and abundance in carp spawning grounds of the Surma River and Tanguar haor, emphasizing water quality, habitat features, spawn availability, and environmental influences. Fish spawn samples were collected with eight "Savar nets" at chosen sites and reared in a fiberglass tank at the mini hatchery for species identification. The representative spawn samples were examined under a microscope for preliminary species identification before rearing. The study found that both the Surma River and Tanguar haor offer ideal conditions for carp spawning due to factors such as water quality, natural food availability, habitat suitability, and favorable climatic conditions. The study identified 39 fish species under the 10 fish groups from both locations, with a higher percentage of carp species (31.42%) in the Surma River in 2021 compared to 2022 (22.50%). In Tanguar haor, the percentage of carp species was 7.55% and 6.50% in 2021 and 2022, respectively. The Surma River's ecological indices (2021-2022) indicated decreased diversity, likely due to environmental degradation, while Tanguar haor showed lower diversity possibly attributable to multiple environmental stressors. The dominant carp species, Labeo calbasu, Labeo bata, and Labeo gonius, were identified in both the Surma River and Tanguar haor. The spawning distribution varied among different locations, with some sites showing a presence of carp species, such as Hajipur (T1) in the Surma River and Alam Duar (T2) in Tanguar haor. The findings highlight the importance of hydrological and environmental parameters in shaping carp spawning habitat distribution and abundance, contributing to aquatic biodiversity conservation and resource management.

UAV-Mounted Tank for Processing Agricultural Land with Liquid Agrochemicals

To process agricultural crops, unmanned aerial vehicles carrying tanks with liquid chemicals are used. The paper highlights that containers made of polypropylene and polyethylene exhibit inferior qualities compared to those made of fiberglass, specifically, in terms of strength, thermal stability, resistance to ultraviolet rays, and service life. (Research purpose) To design and manufacture a tank made of composite fiberglass material with a water hammer damper. (Materials and methods) S-glass and epoxy vinyl ester resin were selected for the tank, as they exhibit superior resistance to chemical influences. To construct the tank elements, spray application, impregnation of glass fiber filler in a closed form, and winding were used. (Results and discussion) A comparative analysis was conducted on tank models, assessing their performance with and without a water hammer damper. The effectiveness of the suggested solution has been substantiated through the utilization of KOMPAS-3D software in the KompasFlow application, Within this software, the hydraulic shock is simulated to propagate inside the tank, reflecting off the walls, and gradually diminishing. Load and strength calculations for the fiberglass tank were performed by considering fiberglass parameters using the APM FEM application. (Conclusions) A tank model designed for application of liquid chemical substances in crop spraying from unmanned aerial vehicles has been developed. Innovative methods were employed in the manufacturing of the tank components. Additionally, careful consideration was given to the feasibility of maintenance and reparability. The tank’s volume (experimental sample) measures 0.0158 cubic meters, with a length of 480 millimeters, a width of 216 millimeters, a thickness of 3.6 millimeters, and a weight of approximately 4 kilograms. The design for mounting the composite tank on the unmanned aerial vehicle ensures that the weight of the unmanned aerial vehicle does not impact the tank.

Improved growth, body composition, and fatty acid composition in striped catfish juveniles, Pangasianodon hypophthalmus, fed with diets containing different oil sources

AbstractStriped catfish are one of the main aquaculture species in Asia. However, the low level of omega‐3 fatty acids in its body makes this species less attractive compared with marine fish. This study aimed to investigate the effect of different oils on growth performance, body composition, and fatty acids in striped catfish juveniles. A basal diet (T0) was formulated to contain no oil, while four other diets (T1, T2, T3, and T4) were supplemented at 4% with different oils, including salmon oil (SALO), soybean oil (SBO), linseed oil (LSO), and rapeseed oil (RSO). Catfish juveniles with initial body weight (23–24 g/fish) were randomly stocked in 500‐L fiberglass tanks, divided into five treatments, three replicates for each, and fed the experimental diets for 60 days. Results from this study revealed that fish fed the LSO‐supplemented diet had significantly (p &lt; 0.05) improved whole body omega‐3 (alpha‐linoleic acid, 18:3n3) fatty acid levels (7.86%), total n‐3 fatty acids (9.12%), and higher growth than those fed the other diets. In conclusion, the findings suggest that linseed oil can be used to improve growth, omega‐3 fatty acid, C18:3–3 (ALA), and total n‐3 PUFA deposition in the whole body of striped catfish juveniles.

Consumption of periphyton and bioseston by Mozambique tilapia in aqua dams with three different substrates

Periphyton-based aquaculture can reduce feed input costs. Here we characterised the periphyton and bioseston formation in aqua dams stocked with net, plastic, and stone substrates. The consumption of periphyton and bioseston from the net substrate by Mozambique tilapia Oreochromis mossambicus fingerlings was evaluated. Three experiments were conducted. In the first experiment, net, stone, and plastic were deployed in triplicates in aqua dams. The net substrate registered the highest (7.74 ± 1.45 g m-2, ±SE) periphyton biomass. Network analysis showed connectedness between the substrates. The degree centrality showed that the net substrate had the highest score, indicating that there were more groups of species with similar functions growing on the net substrate. The net substrate was subsequently used in the second experiment to determine the consumption of periphyton and bioseston by tilapia fingerlings in aqua dams. Three treatments were assigned: N100 (fish fed 100% commercial diet); N50 (fish fed 50% commercial diet); and N33 (fish fed 33% commercial diet). Growth performance did not differ significantly among the treatments, although N50 showed a trend for a higher growth. This suggests that periphyton may be capable of nutritionally compensating for the partial withdrawal of commercial feed. A third experiment was conducted in fibreglass tanks to determine the preference of tilapia between periphyton and bioseston. The prominent values showed that tilapia preferred to feed on bioseston. The best growth performance was achieved in a periphyton-based aquaculture system, and deployment of the net substrate is recommended in tilapia ponds.

Dietary methanotroph bacteria meal alleviates soybean meal-induced enteritis by improving immune tolerance and intestinal flora profile of juvenile turbot (Scophthalmus maximus L.)

An 8-week growth trial was performed to investigate the protective effects of methanotroph bacteria meal (MBM) produced from methane against soybean meal-induced enteritis (SBMIE) in juvenile turbot (Scophthalmus maximus L.). Five isonitrogenous and isolipidic diets were formulated: fishmeal-based diet (FM, the control group); FM with approximate 50% of fishmeal substituted by 399.4 g/kg soybean meal (SBM); SBM supplemented with 63.6, 127.2 and 190.8 g/kg MBM (named MBM1, MBM2 and MBM3), each diet was randomly assigned to triplicate fibreglass tanks. Results showed that fish fed with SBM exhibited enteritis, identified by reduced relative weight of intestine (RWI), as well as expanded lamina propria width and up-regulated gene expression of pro-inflammatory cytokines (tnf-α, il-6 and il-8) in intestine. While the above symptoms were reversed when diet SBM supplemented with MBM at the levels of 63.6 and 127.2 g/kg, as well as characterized by up-regulated gene expression of anti-inflammatory cytokines (tgf-β and il-10) and tight junction protein (claudin3, claudin4 and claudin7) in intestine. Intestinal transcriptome analysis showed that the differentially expressed genes between groups FM and SBM predominantly enriched in the JAK-STAT signaling pathway, and the enrichment of differentially expressed genes between groups SBM and SBM supplemented with 63.6 g/kg MBM was in the inflammatory bowel disease (IBD) and JAK-STAT signaling pathway. To be specific, the expression of jak1, jak2b, stat1 and stat5a was significantly up-regulated when fish fed with SBM, suggested the activation of JAK-STAT signaling pathway, while the expression of these above genes was depressed by providing MBM to diet SBM, and the gene expression of toll-like receptors tlr2 and tlr5b showed a similar pattern. Moreover, intestinal flora analysis showed that community richness and abundance of beneficial bacteria (Cetobacterium and acillus_coagulans) were improved when fish fed with SBM supplemented with 63.6 g/kg MBM. Overall, methanotroph bacteria meal may alleviate SBMIE by regulating the expression of tight junction protein, toll-like receptors and JAK-STAT signaling pathway, as well as improving intestinal flora profile, which would be beneficial for enhancing the immune tolerance and utilization efficiency of turbot to dietary soybean meal.

Utilization of an insect-based diet by a herbivorous fish (Oreochromis mossambicus) and an opportunistic predator (Clarias gariepinus)

An 8-week feeding trial was conducted to evaluate the effect of Alates termite (Macrotermes falciger) based diet in a herbivorous (Oreochromis mossambicus) and an opportunistic predator (Clarias gariepinus). Five diets were formulated to replace fishmeal at 0, 10, 30, 50, and 70 % and were denoted D1, D2, D3, D4, and D5, respectively. Clarias gariepinus sub-adults (209.24 ± 2.41 g/fish) were stocked at 5 fish per tank in recirculating fibreglass tanks (400 L) in triplicates. Oreochromis mossambicus juveniles (7.4 ± 4.78 g/fish) were randomly stocked at 10 fish per tank in recirculating fibreglass tanks (400 L) in triplicates. Fish were fed their allocated diets, twice a day to apparent satiation. Growth performance indices (specific growth rate, thermal-unit growth coefficient) were lowest at inclusion level above 50 % in both species (P < 0.05). The nutrient utilization indices (feed intake, protein efficiency ratio) were lowest at inclusion level above 50 % in both species. The organosomatic indices (condition factor, hepato-somatic index, viscero-somatic index) were not influenced by the inclusion of Alates termite meal in both species. The aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not influenced by Alates termite meal in O. mossambicus (P > 0.05). However, AST and ALT levels significantly increased at inclusion levels above 50 % in C. gariepinus (P < 0.05). The triglyceride, cholesterol, and glucose levels showed no significant difference across diets in both fish species (P > 0.05). The study showed that both species may utilize an insect-based diet up to 50 % inclusion levels without adverse effects on growth performance and nutrient utilization.

Survival Rate and Growth Performance of Holothuria scabra Towards Different Stocking Densities and Feeding with Spirulina

Holothuria scabra is widely used in traditional medicine or consumed as a healthy or exotic food, causing wild stocks to decrease. Therefore, aquaculture is the best solution to address this issue and support the growing market demand. However, up to now, H. scabra production is facing problems related to the nursery phase, survival rate of larvae and juveniles, production cost, and broodstock for mass production. In this study, the juveniles of H. scabra were divided into three different stocking densities and fed with 1 g of dissolved Spirulina powder once on alternate days. Their length was recorded every two weeks. After six weeks, the juveniles reared with 100 individual densities showed the highest survival rate at 80% compared to 200 and 400 stocking densities. Meanwhile, every tank showed a positive growth rate, indicating that Spirulina powder could potentially promote the growth of juvenile H. scabra. The specific growth rate for stocking density at 100, 200, and 400 were 1.2, 0.86, and 1.37%/day, respectively. In conclusion, the optimum initial stocking density is between 100 and 200 individuals for a 1-ton fibreglass tank with a 500 L water capacity. The Spirulina can be used as the main protein source as compared to other diets for juvenile H. scabra.

Biofloc System with Different Carbon Sources Improved Growth, Haematology, Nonspecific Immunity, and Resistivity against the Aeromonas hydrophila in Common Carp, Cyprinus carpio

Biofloc technology (BFT) is one of the most sustainable aquaculture system, which is based on the principle of nutrient recycling and addition of carbon to enable heterotrophic microorganisms to the system. To evaluate the performance of the biofloc culture system for Cyprinus carpio fingerlings, a 60-day growth trial was conducted. The fingerlings (n = 600) of average body weight (4.92 g ± 0.14) were stocked in 12 circular fiberglass tanks (300 L, volume 10.59 cft) to form three biofloc treatments (T1, T2, and T3) along with one control group. The carbon sources for treatments were sugarcane molasses, tapioca, and wheat. The C/N ratio of 15 was maintained for all treatments. After 60 days of rearing, the fish were challenged with Aeromonas hydrophila, and the relative percentage survival (RPS) was observed over 14 days. A haematological, nonspecific immune, and stress parameters were analyzed using blood and serum samples collected at intervals of 20, 40, and 60 days. According to the results, the carbon sources affected the water quality parameters but were still adequate for fish welfare. An increased biofloc volume was observed with tapioca. Growth performance and better feed conversion ratio were recorded in biofloc with the tapioca group. The hematological parameters, including haemoglobin (Hb), hematocrit (HCT), white blood cells and lymphocytes were significantly (P &lt;0.05) higher in biofloc-based tapioca group than in other treatments and control. Further, the serum protein, globulin, albumin, total immunoglobulin, and respiratory burst activity were also found significantly (P &lt;0.05) higher in biofloc with tapioca as carbon source. However, the lysozyme activity was higher in biofloc with the wheat group. The RPS in tapioca was significantly higher, followed by biofloc with wheat. In conclusion, the tapioca-based biofloc can improve C. carpio growth, haematology, and nonspecific immune response under zero water exchange.

Growth, survival and food utilization efficiency of longfin batfish (Platax teira Forsskål, 1775) larvae reared under different salinity levels

Salinity is crucial in fish larval rearing. In longfin batfish (Platax teira), little research has been conducted regarding the specific effects of salinity on growth, survival, deformity, and food utilization efficiency. This study aimed to determine the optimal salinity level for larval rearing of the longfin batfish by testing five different salinity levels (10, 15, 20, 25, and 30‰). Larvae of 1.5 cm in length and 0.2 g/fish in weight were stocked in cylindrical fiberglass tanks (300 L) at a density of 1 fish/L. The fish were fed to meet their dietary requirement and divided into four daily feedings. Each treatment was replicated three times over a 28-day period of rearing. The results revealed that salinity significantly influenced the growth (length, weight, biomass), and food utilization efficiency of the longfin batfish larvae. Overall, larvae reared at salinity levels of 15-20‰ exhibited superior performance compared to those exposed to salinity levels of 10, 25, and 30‰. However, salinity did not affect the coefficient of variation, survival, and deformity. From these findings, it is recommended to rear longfin batfish larvae at a salinity of 15-20‰ to achieve optimal growth and food utilization efficiency. This study provides valuable insights for longfin batfish larval rearing guidance, contributing to the aquaculture development of this economically valuable species.

Effects of replacement of dietary fish oil with plant oil on growth performance and fatty acid composition of spinefoot rabbitfish, Siganus rivulatus.

A 95-day feeding study was carried out to evaluate the impact of complete replacement of fish oil by plant oils in the growth performance, feed consumption fatty acid and body composition of juvenile rabbitfish, Siganus rivulatus. There were four treatments i.e., A (fish oil diet), (linseed oil diet), C (soybean meal oil diet) and D (sunflower oil diet). The experimental trial was conducted in twelve 1.5-m3 fiber glass tanks (n=3). Spinefoot rabbitfish juveniles had an average initial weight of 0.948 g ± 0.124 g and they were stocked at 50 fish per tank. Fish fed diet A showed significantly better growth rate, final body weight, and total body weight than fish fed on the other diets. Moreover, the best FCR was observed for diet A followed by diet C and diets B and D had the worst FCR. Fish body composition for crude protein, dry matter, ashes and gross energy at the end of the trial had not differed between the treatments. The highest polyunsaturated fatty acids (PUFA) was found in fish fed diet A followed in decreasing order by diets D, B, and C. Fish oil is a better dietary lipid source for Spinefoot rabbitfish juveniles, Siganus rivulatus, than plant oils. Among plant oils, soybean oil was better than linseed oil and sunflower oil as the main dietary fat source.

Growth and carbon turnover of Piaractus mesopotamicus Holmberg, 1887 (Osteicthyes: Characidae): contribution of extruded feed and natural food.

Piaractus mesopotamicus, is a fish usually farmed in semi-intensive systems with access to natural food and supplementary feed. This study evaluates effects of feed allowance on the productive performance, carbon turnover and proportions of nutrient (carbon) contribution of feed and natural food for the growth of pacu. Juvenile fish were stocked in fiberglass tanks and fed to 100, 75, 50, 25, 0% apparent satiety (ApS), with a practical, extruded (C4 photosynthetic pathway) feed in a randomized design trial (n=3); plankton production for simulated semi-intensive farming system condition was induced by chemical fertilization. A control treatment was set up in tanks devoid of natural food. Data on muscle stable carbon isotope ratios were used to study carbon turnover using a relative growth-based model. Low variation of the δ13C impaired fitting a turnover model curve for the 0 and 25 % ApS treatments. Fish of the 100% and 75% ApS treatments reached circa 95% and 82.85% of the carbon turnover, respectively. Extruded feed was the main nutrient source for the growth of pacu in the semi-intensive, simulated farming condition. The current study contributes to the knowledge of the relationship between feeding rates and carbon turnover rates in the pacu muscle.

Effect of 17α-methyl testosterone on sex reversal and growth performance of Nile tilapia,Oreochromis niloticus

The present study aimed at developing all-male Nile tilapia using17α-methyl testosterone(17α-MT) along with its growth and feed utilization performances. Three days old Niletilapia fry were stocked in plastic jars with 5 L capacity installed in four fiber glass tanks. The fry were fed with 0, 30, 60, and 100 mg MT/kg diets for 30 days. Later, the fry were shifted to hapas installed in a pond and then, reared for four months separately. The fish were fed with the control diet. The results showed that the highest male population(93.6%) was observed in the fish treated with a 60 mg MT/kg diet, while the lowest(82.6%) was observed in the fish treated with a 30 mg MT/kg diet. The results also showed that the fish fed with a 60 mg MT/kg diet had significantly higher mean body weight (24.1±1.40 g), specific growth rate (2.5±0.10%), feed conversion ratio (1.3±0.10), and protein efficiency ratio (0.63±0.11) than the untreated fish treated (control) group. In conclusion, a 60 mg MT/kg diet can be considered as an optimal and economically viable dose for Nile tilapia sex reversal along with its optimum growth and feed utilization performances.