This study evaluated the effect of static and progressively increasing prey density (PD; Artemia/mL) regimens on growth and performance of largemouth bass (Micropterus nigricans) larvae reared in an indoor recirculating aquaculture system. Beginning at 3 days post-hatch (dph), larvae were fed either four static regimens (PD8, PD12, PD16, PD20) or three progressive regimens (PD8-12, PD8-12-16, PD8-12-16-20) where, PD was increased stepwise at 7, 11, and 15 dph. Regimens were stocked at 100 larvae/L except for the Control (25 larvae/L; static PD8). Morphometric traits and average individual weight (IW) were assessed weekly, while survival, biomass, cannibalism, final individual weight, and specific growth rate (SGR) were evaluated at 31 dph. We also estimated partial income for each PD-regimen, based on Artemia input. Morphometric traits increased over time across all feeding regimens, with notochord length ranging from 28.4 to 31.2 mm and IW ranging from 0.43 to 0.58 g at 31 dph. Generally, fish reared in the Control and PD20 regimens had bigger morphometric traits and IW compared to PD16 and PD8-12-16-20. Highest survival (86.6%) was recorded in the Control. Final biomass (224 g) and cannibalism (<10%) were lower in the Control than all other PD-regimens (ranged from 488.3 to 572.3 g and 23.0 to 40.4%, respectively). No significant PD-regimen effects were detected for length-based SGR (>5%/day) or weight-based SGR (>15%/day). PD20 achieved growth comparable to the Control but yielded lower partial income. In contrast, PD8-12 achieved similar growth and survival outcomes to the high static PD-regimen (PD20) and the Control while retaining higher returns.

OBJECTIVE:The present study examined the effect of humic substance and butyric acid blend (HSB) supplementation, with and without yeast cell wall (YCW), on gut morphology, immunity, and resistance to Flavobacterium covae, Edwardsiella ictaluri, and their coinfection in juvenile Channel Catfish Ictalurus punctatus. METHODS:A feeding trial was conducted in a recirculating aquaculture system with Channel Catfish fingerlings (19.7 ± 0.2 g). Thirty-seven Channel Catfish were randomly assigned into four dietary groups with supplemented feed (g/kg): HSB (2.0 HSB), YCW (0.5 YCW), HSB + YCW (1.0 HSB, 0.25 YCW), and a control group (not supplemented), each consisting of eight replicates. After 45 d of feeding the diets, growth performance was assessed and head kidney, spleen, and gill tissues were sampled for gene expression, while serum was collected for lysozyme activity. Subsequently, fish were pooled by treatment and challenged by immersion with either E. ictaluri (S97-773; 7.4 × 106 CFU/mL), F. covae (ALG-00-530; 1.2 × 106 CFU/mL), or coinfection with simultaneous half-doses of both bacteria. RESULTS:No significant differences were observed in fish growth performance and survival across treatments. However, Fulton's K-factor was significantly higher in the HSB group compared with the control. Serum lysozyme activity was significantly higher in the HSB group, while a numerically higher body mucus lysozyme activity was observed in the HSB + YCW group. No diet-related cytokine gene expression differences were observed in the kidney and splenic tissues. However, differences were observed in the expression of lysozyme genes lysc and lysg in the gill, with the highest expression in the YCW group. Furthermore, expression of ctsd (cellular protease) and defb (antimicrobial peptide) were different across all groups. Specifically, ctsd was upregulated in the HSB group when compared with the control. The expression of defb was upregulated in all treated groups, including HSB, YCW, and HSB + YCW, compared with the control group. After a 14-d bacterial challenge with either F. covae, E. ictaluri, or simultaneous exposure to both, significant differences in survival probabilities were observed across the treatment groups in the single E. ictaluri and coinfection groups but not in the F. covae group. Survival following E. ictaluri challenge varied among groups, with higher survival observed in the HSB group (79%) compared with the control fish (52%). Similarly, the HSB group showed improved survival (72%) compared with YCW (30%), HSB + YCW (45%), and the control group (30%) within the coinfected groups. Furthermore, the survival rate of Channel Catfish was lower in the coinfected groups than in those solely infected with E. ictaluri. CONCLUSIONS:Feeding Channel Catfish with a dietary humic substance and buryate blend reduced the susceptibility of Channel Catfish to E. ictaluri and coinfection with F. covae. These research findings have potential practical implications for fish health and provide an alternative tool for the management of coinfections in the catfish industry.

ABSTRACT Plant‐based proteins, such as soybean meal (SBM), have shown promising results in cultured species but also present challenges due to their nutrient composition and inherent antinutritional factors. This study investigated how the replacement of solvent‐extracted SBM with low oligosaccharide soybean meal (LSBM) or enzyme‐treated soybean meal (ESBM) impacts growth, body composition and health of largemouth bass (LMB; Micropterus nigricans) fingerlings. The basal diet containing 50% SBM was replaced with either LSBM or ESBM at 0%, 40%, 60%, 80% and 100%. Replicate tanks of 15 LMB (8.55 ± 0.18 g) were assigned to one of the nine formulated diets and fed over six weeks. At termination, the treatment diets influenced the growth performance. Specifically, final weight was improved for LSBM80% (27.16 ± 0.90 g) compared to the basal diet (22.05 ± 0.59 g). Final weight, weight gain and thermal growth coefficient displayed improvements for 60%–100% ESBM‐inclusion diets (26.83–28.31 g, 18.31‐19.64 g and 0.52–0.57, respectively) compared to the basal (22.05 ± 0.59 g, 13.61 ± 0.61 g and 0.39 ± 0.02, respectively). ESBM60% (1.14 ± 0.06) and ESBM100% (1.18 ± 0.06) showed enhancement for the feed conversion rate compared to the basal (1.53 ± 0.06). Blood Cl− levels were reduced in ESBM100% (69.00 ± 4.00 mmol L−1) compared to basal diet (86.00 ± 2.00 mmol L−1). Mg2+ levels were elevated in LSBM40%, LSBM60% and ESBM100% (3.59–3.69 mmol L−1) compared to the basal (2.88 ± 0.10 mmol L−1). Histological analysis of the distal intestine revealed no negative impact on intestinal health. These findings suggest that using higher inclusion levels of LSBM and ESBM proteins displayed enhanced growth in LMB compared to only using conventional SBM.

Rearing of largemouth bass (LMB) in recirculating aquaculture systems (RAS) has presented challenges during early life, often resulting in high mortalities. Because LMB are visual feeders, tank color and light intensity may influence foraging and survival. In this study, LMB were reared in five tank colors (black, blue, green, red, white) under two light intensities (400, 900 lx). Fish were sampled at 1, 8, 15, 22, and 26 days post-hatch (DPH) by capturing digital images of 12 fish/tank. Measurements included total length, notochord length, jaw length, eye diameter, myotome height, body area, and fin-fold area. At termination (27 DPH), 50 fish/tank were sampled for individual wet weights. Survival, cannibalism, biomass, wet weight uniformity, and morphological deformities were also determined. Fish were 6.01 f 0.14 mm in total length at 1 DPH and 26.72 f 0.94 mm at 26 DPH. The light intensity by age interaction was significant for jaw length, where fish reared at 400 lx exhibited larger jaws at 22 to26 DPH. Light intensity influenced body area and fin-fold area, being larger at 400 lx. Tank color affected survival, with black tanks yielding significantly higher survival (77.44 f 7.13%) than green, red, and white (63.24-67.33%), but not blue tanks (71.89 f 5.12%). Cannibalism differed among tank colors and was lower in black (6.46 f 5.04%) compared to green, red, and white (13.69-20.67%), but not blue tanks (11.96 f 6.97%). No morphological deformities were detected in black, blue, or green tanks. However, morphological deformities occurred in white (4.50 f 4.04%) and red tanks (2.33 f 0.82%). Using darker tanks combined with low light may improve LMB culture by enhancing hatchery production.

Plant‐based ingredients are a cost‐effective replacement for animal protein sources in shrimp feeds. However, the presence of antinutritional factors (ANF) like nonstarch polysaccharides (NSP) and phytate limittheir inclusion. NSP are known to increase gut viscosity, decreasing the diffusion rate of substrates and preventing endogenous enzymes from breaking down feed molecules. Dietary exogenous enzymes like xylanase (XYL) and phytase (PHY) enhance the degradation of ANF into more readily available compounds. Therefore, this study aims to evaluate the effect and interactions of XYL, PHY, and a protease complex (PCO), individually or in combination, on growth performance, nutrient utilization, nutrient digestibility, and gene expression of Pacific white shrimp ( Litopenaeus vannamei ) over 8 weeks. Juvenile shrimp (0.23 ± 0.01 g initial weight) were reared in a recirculating aquaculture system (RAS) using green brackish water and fed one of eight diets (35% protein, 8% lipid) supplemented with enzymes individually or in combination. Neither individual enzyme supplementation nor their combinations affected growth performance parameters, whole‐body proximate composition, protein and phosphorus retention, or gene expression of trypsin , alp , amylas e, and fasn ( p > 0.05). However, differences in digestibility of dry matter, energy, and crude protein were observed ( p < 0.05). These results suggest that exogenous enzyme supplementation offers limited benefit to Pacific white shrimp reared in green‐water systems, possibly due to supplemental nutrition provided by the green‐water environment.

OBJECTIVE:This study evaluated the effect of commercial Bacillus spp. probiotics on growth performance, immunity, gut microbiota composition, and disease resistance to Vibrio parahaemolyticus in Pacific white shrimp Litopenaeus vannamei that were reared under biofloc conditions. METHODS:A 56-d feeding trial was conducted in a static biofloc system with postlarval shrimp (1.00 ± 0.03 g). A total of 1,080 shrimp were randomly assigned to three groups: two treatment levels (recommended dose [PRO × 1] and a doubled dose [PRO × 2]) of a commercial probiotic blend, PRO4000X, alongside a control group (CTL; no probiotics). At the trial end point, hepatopancreas and gut samples were collected for gene expression. Gut samples were also obtained for gut microbiota analysis via 16S ribosomal RNA sequencing, and hemolymph samples were withdrawn to measure the total hemocyte count. RESULTS:Probiotic applications did not significantly affect growth performance, including final biomass, mean weight, survival, and feed conversion ratio under the experimental conditions. The probiotic-treated shrimp exhibited enhanced survival during a V. parahaemolyticus (strain A3) challenge, with significantly lower mortality rates (P < 0.001; 42.5 ± 4.3% for PRO × 1 and 60 ± 6.5% for PRO × 2) relative to the CTL (100 ± 0.00%). Immune parameters, such as total hemocyte count, did not differ. Interestingly, the expression of the antioxidant gene sod (superoxide dismutase) in the shrimp gut was significantly downregulated in the PRO × 1 group relative to the control (P = 0.030), which suggests reduced oxidative stress under probiotic supplementation. The analysis of the gut microbiota revealed differences in alpha diversity, specifically in evenness and Shannon index, which were significantly higher in the PRO × 1 group. The analysis of the bacterial composition also revealed minor shifts in the dominant genera. Notably, Lysobacter was more abundant in the PRO × 1 group, which potentially reflects positive modulation of gut microbial communities in response to probiotic supplementation. CONCLUSIONS:Overall, the application of PRO4000X probiotics significantly reduced the V. parahaemolyticus infection in the shrimp that were reared in biofloc water and supported the regulation of immunity and microbial communities in the gut. These findings indicate that probiotics potentially help to improve shrimp health when shrimp are cultured in biofloc systems.

The demand for cost-effective solutions for feeds in the aquaculture industry has increased over the last decade, and one of the most essential and expensive nutrients is protein. The present study was intended to further research in protein demand of the Pacific white Shrimp through feed management techniques and use of passive acoustic monitoring (PAM) to evaluate feeding behavior. Four diets containing different levels of crude protein (CP) (25, 30, 35 and 40 %) were formulated using soybean meal and poultry by-product meal as primary protein sources. The four diets were offered at various feeding levels based on standard feeding protocol (SFP) to allow for equal feed inputs as well as daily protein delivery, additionally each diet was also fed at the usual level of SFP. Treatments were used on a growth performance trial. At the end of the growth trial, all growth parameters showed significant differences between treatments except for survival. The highest final weight was recorded for treatment 40/114.3 (CP/SFP), which was statistically different from treatments with 25/100 and 30/100. All treatments with matched protein intake of 40 % of daily ration achieved similar growth but increased FCR as dietary protein decreased. An acoustic trial was done using the same four diets as treatments, in which feeding response was evaluated during 30 min. Number of clicks within the first 15 min and feed consumption (g) showed a similar trend of decreasing values from the highest protein diet (40 %) to the lowest (25 %). Findings indicate that higher protein intake will improve growth, however it becomes less efficient as CP in the diet decreases. Additionally, the use of higher protein diets (even without marine protein as main source) improves the initial response of the shrimp.

Phytogenic feed additives derived from plant-based sources like essential oils and extracts are increasingly utilized in aquaculture. They have the potential to bolster immune responses, enhance disease resistance, and improve growth performance in fish. The current study investigated the effect of commercial phytogenic feed additives (Actifor Pro, Actifor Power, Fresta Protect, Syrena Boost, and Enviro QS) on growth performance, immunity and disease susceptibility of juvenile channel catfish (Ictalurus punctatus) within an indoor recirculating system. Over eight weeks, 750 juvenile channel catfish (14.8 +/- 0.5 g, initial weight) were stocked in 30 tanks (25 fish tank(-1)) and fed either a control or five phytogenic-supplemented diets. Growth performance, including weight gain, survival, and feed conversion ratio, was similar among treatments (P > 0.05). Following the feeding trial, fish were challenged with virulent Aeromonas hydrophila (vAh; ML09-119; 1.86 x 10(7) CFU mL(-1) immersion dose in water). Seven days post-exposure to vAh, Kaplan-Meier survival analysis indicated improved survival probability in the phytogenic-treated groups (P = 0.009). Sera lysozyme activity significantly differed across the groups (P = 0.014); moreover, the catfish fed with Fresta Protect had higher sera lysozyme activity than the control group. Biochemical testing of an additional thirteen markers in the sera, including ions, glucose, digestive enzymes, and cholesterol, did not reveal any treatment-related differences. The expression of immune-related genes (il1b, il8, tnfa, and tgfb) was not affected after eight weeks of the feeding trial, regardless of the dietary treatment. 16S rRNA sequencing showed that Cetobacterium somerae was the most abundant gut microbe across all diets, with the highest prevalence in the Syrena Boost group (80.54 %). While the overall microbial diversity did not change significantly between treatments, dietary phytogenic compounds influenced the presence or abundance of certain bacterial species, such as Cellulosilyticum lentocellum, Clostridium disporicum, Plesiomonas shigelloides, and Niameybacter massiliensis.

This study aimed to determine the effect of replacing fish meal (FM), soybean meal (SBM), and corn protein concentrate (CPC) in an equal ratio with corn fermented protein (CFP) on Pacific white shrimp, Litopenaeus vannamei growth, feed utilization efficiency, hemolymph parameters, and physiological gene expression. A green water recirculation system was employed with a stocking density of 30 shrimp per tank (~35 shrimp/m2) and an initial weight of 0.216 ± 0.007 g (mean ± standard deviation). Six experimental diets were investigated over 8 weeks. The primary protein sources in the basal diet were systematically replaced (0% – 25% diet) with CFP. No significant changes in shrimp growth indicators were found between shrimp reared on the various diets (p >0.05). We found few significant differences in feed utilization efficiency (p >0.05), but especially for feed conversion ratio (FCR; p=0.372) shifts in net phosphorus retention (PR; p <0.001) were significant. Physiological gene expression analysis revealed no signs of gut inflammation or digestive enzyme disorders (p >0.05). At the same time, the hemolymph index exhibited similar patterns with no statistically significant outcome (p >0.05). The results showed that, under a setting with natural productivity, different replacement levels did not impair the growth response, feed consumption, physiological gene expression, and hemolymph indicators of Pacific white shrimp when appropriately balanced with other protein sources. The results demonstrated the feasibility of replacing the primary protein source with CFP in practical feed applications. Overall, using CFP in shrimp feed formulation resulted in a good growth rate with no adverse effects.

Dissolved oxygen (DO) is a critical limiting factor in intensive shrimp farming. It is well known that hypoxia can reduce feed intake, but accurately quantifying this behavioral response is challenging with traditional monitoring methods. Passive Acoustic Monitoring (PAM) offers a non-invasive, high-resolution alternative to assess shrimp behavior based on mandibular click emission during feeding activity. This study aimed to use PAM to evaluate the effect of progressive hypoxia on the feeding behavior of Penaeus vannamei. Groups of shrimps (16 g) were exposed to four DO levels of 5 (control), 3, 2, and 1 mg/L. The low levels (3, 2, and 1 mg/L) were achieved using two distinct methods: a "gradual reduction" by turning aeration off and a more "abrupt reduction" via nitrogen gas. Shrimp food consumption (FC) and acoustic click activity were measured over 30 min and analyzed using oneway -ANOVA, linear regression, and Generalized Least Squares (GLS). Results showed that FC and click activity were strongly correlated (R = 0.807, p < 0.001) and the method of oxygen reduction significantly influenced both behavioral responses. Under gradual reduction, food consumption remained statistically similar at 5, 3, and 2 mg/L, but dropped significantly at 1 mg/L, accompanied by reduced click activity. Under abrupt reduction, food consumption showed a clearer DO-dependent decline, with the main significant drop occurring at 1 mg/L. The GLS indicated that under hypoxia, click activity peaked early and declined rapidly, whereas under aeration (5 mg/L) clicking rates remained more stable over time. These results suggest that the method of dissolved oxygen reduction (gradual vs. abrupt), rather than the final concentration alone, significantly influences the feeding behavior of P. vannamei. We validate PAM as a precise tool to detect hypoxic stress in real-time, offering a method to optimize feeding and aeration management.

The present study aimed to evaluate the impacts of different types of soybean meal (SBM) and animal protein on the growth performance, feed utilization efficiency, intestinal histology, and physiological gene expression of the Pacific white shrimp (Litopenaeus vannamei). Two trials were conducted, one in a green water and one in a biofloc-based recirculating system, each over an 8-week period. A total of nine diets were evaluated which included the basal diet containing 48 % solvent-extracted soybean meal (SE-SBM) as a primary protein source. The SE-SBM was then replaced on an isonitrogenous basis with low oligosaccharide soybean meal (LO-SBM), soy protein ceoncentrate (SPC), enzyme-treated soybean meal (ET-SBM), and expeller-pressed soybean meal (EP-SBM) on an isonitrogenous and isolipidic basis. An animal protein-based diet was also included as a reference. Except for the survival rate (P > 0.05), all growth indices in the experiment showed significant differences among treatments (P <= 0.05). In both trials feeds containing 100 % replacement of SPC performed poorly in terms of growth and feed utilization and LO-SBM diets resulted in better performance of the shrimp. Both studies found no enteritis-related histomorphological changes in the shrimp guts (P > 0.05, omega(2) = 0.000, 95 % CI: 0.000, 0.000). In the green water trial, no health-related gene expression changes within the gut were detected. For the indoor biofloc system, shrimp fed soy protein concentrate and solvent-extracted soybean meal showed an overall down-regulation of the target genes when compared to low oligosaccharide and expeller-pressed soybean meal (P < 0.05). The current study demonstrates that there were no apparent signs of enteritis and soy-based ingredients support shrimp growth that is similar or better than animal-based feeds. More research on plant-based protein sources is needed to optimize the dietary matrix and diversify component sources to enhance shrimp growth performance.

Survival, growth rate, and welfare have always been the primary concerns of shrimp aquaculturists. Accordingly, a number of bioactive feed components have been supplemented in shrimp feed to improve health condition, feed intake, and growth. The present study evaluated the effects of supplementing a high ash, low protein marine bacterial biomass on feeding behavior, growth, proximate composition, hemolymph biochemistry, and digestive enzyme gene expression of juvenile Litopenaeus vannamei. Six isonitrogenous (36% crude protein) and isolipidic (6% crude lipid) diets were prepared to include graded levels (0%, 2.5%, 5%, 7.5%, 10%, and 20% of the diet) of a commercial bacterial biomass. Feed intake and behavior were assessed using passive acoustic monitoring prior to growth assessment. Following acoustic monitoring, juvenile L. vannamei (0.58 ± 0.02 g) were size-sorted and stocked in an indoor recirculating aquaculture system. The experiment consisted of eight treatments, six of which were the diets prepared. The remaining two treatments were to offer shrimp the basal diet or the diet containing 10% bacterial biomass at 115% of the standard feeding ration. Each treatment consisted of five replicate aquaria, and the experiment was performed for 42 days. Results suggest that the inclusion of the bacterial biomass significantly affected shrimp feed consumption, growth, feed conversion ratio (FCR), alkaline phosphatase level, and protein and phosphorus retention (p < 0.05). Results were mainly influenced by bacterial biomass inclusion level. Shrimp offered the 10% bacterial biomass diet exhibited the most weight gain among shrimp offered the standard ration. However, offering shrimp the same diet but at 115% of the standard ration further improved weight gain. The present study suggests that supplementing shrimp feed with 10% of the commercial bacterial biomass we studied would lead to better growth, feed consumption, and feed conversion without adverse effects on hemolymph, overall health or digestion.

This study evaluated the effect of water temperature on the feeding activity of Penaeus vannamei using passive acoustic monitoring (PAM) as a noninvasive tool for real-time behavioral assessment. Juveniles (25.16 +/- 1.38 g) were exposed to five temperature treatments (22.1, 24.1, 27.5, 29.4, and 31.3 degrees C), with four replicates per treatment, under controlled laboratory conditions. Feeding activity was monitored and quantified through acoustic detection of clicks emitted by shrimp mandibles and food consumption (FC) during 30-min feeding periods. Both click production and feed intake peaked at Regular (27.5 degrees C) to Very hot (31.3 degrees C) but declined significantly at cold temperatures of Very cold (22.1 degrees C) and Cold (24.1 degrees C). Acoustic activity correlated strongly with feed intake (r = 0.65, p < 0.001), validating PAM as a quantitative indicator of feeding intensity. Furthermore, a Generalized Least Squares (GLS) model indicated a significant time-temperature interaction, showing that temperature influenced the temporal pattern of feeding in addition to its overall magnitude. These findings confirm that similar to 28-30 degrees C range represents the optimal thermal window for feeding activity in P. vannamei and demonstrate the potential of PAM to support precision feeding and temperature-responsive management in shrimp aquaculture.

ABSTRACT This study evaluated the long‐term effects of a dietary humic substance and butyrate blend (HSB) alone or with yeast cell wall (Beta‐MOS) in channel catfish. Around 1440 fish (31.31 ± 0.24 g) were distributed among 12 outdoor tanks in a pond‐supplied flow‐through design. Four dietary treatments were evaluated in triplicate: Diets containing no supplements (control), 2 g kg−1 of HSB (HSB), 0.5 g kg−1 of yeast cell wall (BM) or a combination of 1 g kg−1 HSB and 0.25 g kg−1 BM (HSB+BM) for 90 days. All growth indices increased over time (p ≤ 0.050); however, diet did not affect growth parameters (p > 0.05), except for per cent weight gain (PWG) (p = 0.027). PWG differed among treatments after 90 days (p = 0.016), with the HSB yielding 470% PWG compared to 400% in the control (p = 0.011). Serum lysozyme activity was unaffected by dietary treatments (p = 0.128) but varied over time (p < 0.001), with higher activity at 30 days compared to 60 or 90 days (p < 0.001). Target immune genes in the head kidney were not different (p > 0.050). Meanwhile, splenic il1b and tnfa expression varied over time (p = 0.036; p = 0.023), with upregulation at 30 days. Gut microbiome analyses showed treatment effects on richness after 90 days (p = 0.027), while beta diversity was influenced by time rather than treatments. Differential abundance analysis identified opportunistic taxa in the gut after 30 days, followed by commensal colonization at 60 and 90 days. Overall, dietary HSB at 2 g kg−1 showed growth potential in channel catfish. While 0.5 g kg−1 of BM did not affect performance, their combination at half inclusion rates yielded comparable growth. Therefore, HSB has the potential to support long‐term growth performance while maintaining baseline health performance in commercial catfish aquaculture.

Largemouth bass (LMB), Micropterus nigricans, is a valuable freshwater aquaculture species with a rapidly expanding market in North America, yet early feeding strategies remain poorly defined. This study evaluated how larval stocking density (LD), prey density (PD), and their interactions shape early LMB performance in an indoor recirculating aquaculture system. Beginning at 2 days post-hatch (DPH), larvae were stocked into 15-L tanks at 25, 50, or 100 larvae/L and factorially fed Artemia at 2, 4, or 8 nauplii/mL (8 feedings/day; 7:00-23:00). All treatments were fed rotifers (2-8 DPH) and starter diets (4-27 DPH) to apparent satiation. Growth trajectories were assessed using morphometric traits. Survival, specific growth rate (SGR), biomass, and cannibalism were also evaluated. Most treatments showed increased mortality around 16 DPH before stabilizing. Highest survival (similar to 94%) occurred at low LD (25 larvae/L) combined with high PD (8 Artemia/mL). Biomass increased with increasing LD and PD, peaking at LD100 and PD8. Cannibalism was lowest at LD25 x PD8 and highest at LD100 x PD2. Morphometric traits were significantly affected by LD x PD interactions over time, with larger sizes typically observed at a lower LD and higher PD. Strong positive correlations among growth traits increased with age. These results suggest that producers aiming to maximize biomass may utilize higher larval densities (LD100) supported by elevated prey densities (8 Artemia/mL). In contrast, production strategies targeting faster-growing fingerlings may benefit from lower larval densities (LD25) combined with a moderate (4 Artemia/mL) to high (8 Artemia/mL) prey supply.

OBJECTIVE:Phytogenics, which are plant-derived compounds, are increasingly gaining importance in aquaculture as sustainable and natural feed additives that support the performance and health of cultured fish. The current study evaluated the effects of dietary phytogenic supplementation in Nile Tilapia Oreochromis niloticus and the influence of phytogenics on growth, immunity, and resistance against Flavobacterium oreochromis. METHODS:Fish were fed six experimental diets, including a control diet and five commercial phytogenic treatments-Syrena Boost (SY), Actifor Pro, Actifor Power (APO), Enviro QS, and Fresta Protect-for 60 d in a -recirculating aquaculture system. These products included bioactive compounds, such as saponins, thymol, essential oils, and condensed tannins. At the end of the trial, fish were sampled and blood was collected for serum lysozyme and biochemistry analyses, while spleen and head kidney were collected for immune gene expression analysis. After sampling, fish were challenged with F. oreochromis to evaluate resistance. RESULTS:No significant differences in growth performance or nutrient utilization were observed among dietary treatments compared with the control. However, fish that were fed with phytogenic diets exhibited enhanced innate immune responses, as indicated by increased serum lysozyme activity in the APO treatment group (mean ± SE = 17.8 ± 0.76 μg/mL) and elevated serum albumin in the SY and Actifor Pro treatment groups. Although no significant differences were found in the expression of immune-related genes (interleukin-1 beta, interleukin-6, interleukin-8, and tumor necrosis factor alpha), multivariate analysis revealed tissue-specific and diet-dependent immune patterns. During the bacterial challenge with F. oreochromis, all phytogenic treatments resulted in a significantly higher survival compared with the control group, with fish in the SY (∼58%) and APO (∼51%) treatment groups showing the lowest cumulative mortality. CONCLUSIONS:These findings indicate that phytogenic compounds could enhance resistance to F. oreochromis in Nile Tilapia through modulating the innate immune response. Overall, among the five commercial phytogenics evaluated in this study, SY and APO showed the most potential as functional feed additives to improve Nile Tilapia immunity and resistance to columnaris disease.

Feed management and the nutrient content of the diet are two of the most important factors in shrimp culture, as feed makes up around 60% of the total variable costs. Given the cost of protein and its effect on growth, it is critical to understand the effects of both dietary protein and feeding rates on shrimp performance. Hence, the aim of this study was to evaluate the effect of different protein intake levels on growth performance, nutrient retention efficiency, and whole-body composition of Pacific white shrimp (Litopenaeus vannamei) using different levels of crude protein (CP). This was done by feeding four practical diets with 40%, 35%, 30%, and 25% of CP, which were fed at two different rates, one of them being the standard feed rate (100%) and a second adjusted rate to match the protein supplied (40% protein equivalence), resulting in a total of eight treatments with four replicates each. The total ration for each of the treatments was spread out into four feedings per day. Juvenile shrimp (0.41 ± 0.01 g) were stocked into a green water outdoor recirculating system with 32 circular tanks at a density of 30 individuals/tank and reared for 11 weeks. A recirculating aquaculture system (RAS) with green water (~30°C) was used for this trial, which consisted of a central reservoir (⁓1000 L) and treatment tanks (⁓800 L). At the end of the trial, growth performance parameters including final weight, weight gain (WG), biomass, and feed conversion ratio (FCR) were found to be significantly different among treatments (p  < 0.05). Average survival was between 94% and 98% for all the treatments. All final body composition values (dry matter, CP, and minerals) did not show significant differences between treatments except for fat (p  < 0.05). However, feed utilization measurements including apparent net protein retention (ANPR), and phosphorus retention (PR) showed to have significant differences (p < 0.01), ranging 49%-66% and 16%-27%, respectively. The results from this study demonstrated that treatments with higher protein intake resulted in the best growth performance, meanwhile treatments with lower protein intake had the highest nutrient retention values.

Use of corn-fermented protein (CFP), a new product produced using Fluid Quip Technologies, as a protein source in aquaculture feeds, constitutes a promising option due to its dependable supply and cost-effectiveness. In this study, two growth trials were performed to evaluate the effectiveness of CFP products such as CFPA (48% crude protein [CP]), CFPB1 (50% CP), and CFPB2 (60% CP) from two different sources (A and B) in practical diets for juvenile Pacific white shrimp (Litopenaeus vannamei). The test diets in both trials were formulated to be isonitrogenous and isolipidic (36% crude protein and 6% crude lipid). These diets were produced by supplementing the basal diet with 5%, 10%, 15%, and 20% CFPA or 4%, 8%, 12%, and 16% of CFPB1 and CFPB2 to replace soybean meal (SBM) on an isonitrogenous basis. In a 6-week experiment, shrimp (1.02 ± 0.02 g mean weight, 15 shrimp per tank, n = 6) were offered CFPA diets. Growth parameters and protein retention showed no significant differences among diets. However, a significant feed conversion ratio (FCR) increase was observed when shrimp were fed a diet containing 20% CFPA compared to the basal and 5% CFPA diets. Physiological gene expression analysis revealed no signs of gut inflammation or shifts in hepatopancreas digestive enzymes (p  > 0.05). However, the expression of immune-related tnf-α gene was significantly upregulated (p  < 0.05) in shrimp-fed CFPA 25% diet compared to CFPA 5% and control groups. In a 7-week experiment, shrimp (0.55 ± 0.01 g, 15 shrimp per tank, n = 5) received experimental CFPB1 or CFPB2 diets. No differences were observed in growth performance. This research highlights the potential of CFP as a protein source in shrimp diets by expanding the range of feed ingredients and identifying optimal inclusion levels.

Three Trials were performed to understand better how soy processed in different ways impacts the growth, feed conversion ratio, and health of the Florida pompano ( Trachinotus carolinus ). The first two growth Trials were performed to evaluate the efficacy of an open soy-based diet compared to a commercially produced, fish meal (FM)–based diet. Trial 1 compared a soy-based diet to a commercial FM-based diet using juvenile fish (23.2 ± 1.87 g) across six replicates over 42 days. The FM-based diet significantly outperformed the soy diet in final biomass ( p = 0.026), weight gain ( p = 0.006), and feed conversion ratio (FCR) ( p = 0.015). Trial 2 used larger fish (38.1 ± 0.86 g) with three replicates over 56 days and found no significant differences between diets. Histological samples of the distal intestine showed no statistical differences in symptoms conducive to soy-induced enteritis between the practical soy diet and the commercial FM diet. Trial 3 evaluated nine experimental soy-based diets in juvenile pompano (4.82 ± 0.09 g) across quadruplicate tanks for 76 days. The basal diet containing 49.97% solvent-extracted soybean meal (SBM) was compared with diets where SBM was replaced at 50% or 100% with low oligosaccharide SBM, soy protein concentrate, or enzyme-treated SBM, or at 25% or 50% with expeller-extruded SBM. No significant differences were found in weight ( p = 0.493), survival ( p = 0.925), or FCR ( p = 0.874). Histological analysis showed no adverse intestinal effects in lamina propria thickness, lamina propria cellularity, connective tissue thickening, or abundance of goblet cells.

Yellowtail snapper (Ocyurus chrysurus) is a marine snapper of the family Lutjanidae that has potential as a mariculture species and as a research model for Lutjanid snapper species, since it is relatively easy to spawn and rear. Hence, there is an interest in identifying the appropriate diets for its culture. The utilization of practical diets and their effects on fish growth performance and body composition are currently poorly understood. To study the effects of practical diets for yellowtail snapper with different protein sources, such as fishmeal (F), poultry meal (P), and soybean meal (SBM), a 14-week growth trial was conducted in juveniles with a mean initial weight of 2.03 +/- 0.06 g. The trial included a dose-response in replacing fishmeal with poultry meal (F30, F15:P15, P30, and F15:SMB40), which were formulated to have 40 % protein and 10 % lipid levels. Histological measurements of the distal intestine mucosal length, thickness of the mucosa, lamina propria, submucosa, and serosa, as well as in the histological scoring of the lamina propria folds, connective tissue, and large vacuoles showed no significant differences (p > 0.05) among fish fed F30, P30, and F15:SMB40. Results show no adverse effects on growth performance and intestinal histology in yellowtail snapper juveniles when they were fed diets containing low levels of different protein sources and high levels of soybean meal. While diets containing high levels of fishmeal as protein source were best, the results of this study indicate that yellowtail snapper can be grown effectively (i.e. with no significant enteritis or decreases in growth performance) using diets containing a variety of different protein sources allowing for potentially decreased grow-out feed costs and improved overall economic production efficiency.