Water Recirculation System Research Articles

Utilização de um gerador de bolhas ultrafinas para oxigenação de tanques de criação de tilápia do Nilo (Oreochromis niloticus) em sistema de recirculação

The objective of this work was to evaluate the use of an ultrafine bubble generator of own manufacture for oxygenation of Nile tilapia (Oreochromis niloticus) breeding tanks in a recirculating water system. The research was divided into two steps: 1) oxygen saturation test; 2) application of ultrafine bubble production technology for the breeding of Nile tilapia. In the first step, the water of a 2.0 m3 test tank was completely deoxygenated and the ultrafine bubble generator was turned on for 60 min. In the second step, the generator was connected to the water recirculating system for breeding of Nile tilapia to compare the overall performance of this system with other under conventional aeration system. The ultrafine bubble generator could reach 100% oxygen saturation in the test tank (27.8 °C) in approximately 21 min and, at the end of 60 min, the concentration was 21.8 mg L-1 (277.52% saturation). The results showed significant difference (p<0.05) between the mean dissolved oxygen concentration in the treatment with ultrafine bubbles (9.80 ± 3.68 mg L-1) and the treatment with conventional aeration (3.47 ± 0.88 mg L-1). No significant difference (p>0.05) was found for the zootechnical performance parameters evaluated. The conclusion was that the ultrafine bubble generator is more efficient to maintain a high dissolved oxygen concentration in the recirculating water in Nile tilapia breeding tanks than the conventional aeration system.

Application of The Completely Random Design Statistics Method For Analysis of Different Filter Types In Fresh Water Fish Pool Water Recirculation System

In meeting their daily water needs (bathing and washing), the majority of the people of South Kalimantan (South Kalimantan) have been using river water and peat well water, as is the case for fresh water fisheries. However, the water used is cloudy and smells because it is water that is polluted by household waste, and of course it shows the quality of the water that is still being debated for the process of fish cultivation. In the process of cultivating freshwater fish, the standard mechanism is still used, namely by making tarpaulin ponds for fish ponds and river water as a medium for fish cultivation and the process of providing feed. In the process there are several things about water quality and conditions, and several other issues, namely about water circulation, temperature, humidity, pH and oxygen regulation of fish pond water. Fish excrete waste from leftover feed and metabolism which contain lots of ammonia (Effendi, 2003). Fish excrete 80-90% of ammonia through osmoregulation processes, feces and from urine. To produce quality pond water as a medium for fish cultivation, it is necessary to have a proper and good water filter. This study aims to obtain the best filter substrate in increasing the growth and survival of freshwater fish fry reared using polluted river water in a tarpaulin pond with a recirculation system. The filter method used in this study was an experimental method using one factor Completely Randomized Design (CRD) with four treatment levels and three replications. The treatments applied were P0 = Zeolite, Charcoal, Japmate, Bio Foam, P1 = Bamboo, Charcoal, Japmate, Bio Foam, P2 = Bioball, Charcoal, Japmate, Bio Foam and P3 = Bioring, Charcoal, Japmate, Bio Foam. The resulting data were analyzed for analysis of variance (ANOVA), then continued using the BNT test with 95% and 99% confidence intervals. From the results of the study, the measurement results obtained were for the specific growth rate test (SGR) of 1.15%, the survival test (SR) of 86.66% and the feed conversion ratio test (FCR) of 3.10%. While the supporting parameters are water quality, namely the results of water quality, namely, temperature 28.1 – 30.3 0C, pH 7.4 – 8.1, DO 5.24 6.53 mg/L, NH3 0.06 – 0.40 mg/L, NO2 0.056 – 0.90 mg/L and NO3- 0.28 – 0.190 mg/L. In addition to producing filter products that can support SGR, SR and FCR in freshwater fish, it is hoped that this research will also produce scientific paper outputs that will be published in International Conferences/International Journals and become part of the Study Program's Coursebook for the Accounting Department. Computerized Poliban Accounting and can be applied in the community through the Community Service program

Rearing performance of juvenile yellowtail snapper, Ocyurus chrysurus, in a sea water recirculation system at two different stocking densities

AbstractEvaluation of viability of new marine species in aquaculture systems is important to reduce negative social and environmental externalities, offering sustainable options for supply to fish markets. The objective was to describe the performance indicators of late juvenile yellowtail snapper (243.2 ± 57.1 mean weight of total fish) in an experimental recirculating aquaculture system (RAS) system supplied by seawater to determine its pre‐feasibility. Two densities were stocked, D1: 10 fish/tank (2.6 kg/m3, mean weight 258.3 ± 57 g) and D2: 20 fish/tank (4.7 kg/m3, mean weight 235.6 ± 55.9 g). Fish were fed to satiety with an extruded diet containing 46% crude protein and 12% crude lipid. After 238 days, survival rate was 93% for both densities, and mean weight and biomass were 534.5 ± 19.4 g and 5.7 kg/m3 for D1, and 606.9 ± 34.5 g and 10 kg/m3 for D2. Final feed conversion rate (3.13 for D1 and 3.03 for D2) did not differ significantly between densities. The exponents (b) of the length–weight relationship calculated for D1 (3.15) versus D2 (3.10) and condition factor (2.12 ± 0.07 for D1, and 2.03 ± 0.04 for D2) demonstrated a higher condition factor than those of their wild counterparts. This study is one of the few reports on this species’ performance in late juvenile stage in RAS.

Desempenho zootécnico, grau de esteatose e potencial genotóxico de lambaris Astyanax lacustris alimentados com diferentes níveis de L-carnitina

ABSTRACT L-carnitine perform a major role in transporting long-chain fatty acids into the mitochondria, where they are oxidized. It has been used in animal diets to decrease fat and increase muscle protein. The aim of this study was to evaluate the zootechnical performance, degree of steatosis in the liver, and genotoxic potential in Astyanax lacustris fed with different levels of L-carnitine (LC). Yellowtail tetra juveniles (n = 140) were distributed in 20 tanks of 70 L, with seven fish in each, in a water recirculation system with controlled temperature (27±0.1⁰C). The treatments with different levels of L-carnitine supplementation were: 0 (control), 250, 500, 750, and 1000 mg of LC per kg of food. The diets were provided twice a day for 60 days. The results showed that the different levels of LC did not affect (P>0.05) weight gain, survival, viscerosomatic index, and the liver hepatocytes showed a normal appearance. However, the use of LC supplementation showed genotoxic potential with a significant difference (P<0.05) for cell alterations when compared to the control at concentrations above 500mg kg-1.

Extrato de própolis como aditivo alimentar para juvenis de tilápia-do-nilo

ABSTRACT This study was conducted to investigate the effects of dietary propolis alcohol extract supplementation on growth performance, digestibility, intestinal morphometry, and physiologic parameters Nile tilápia (Oreochromis niloticus L.) juveniles. For performance experiment and intestinal morphometry, 120 fish averaging 1.41±0.3g were randomly distributed into 24 tanks (70L each) in a closed recirculation water system with constant aeration and biofilter. The animals were distributed into four treatments using a completely randomized design with six replicates per treatment. The treatments consisted of four pellet feeds with different alcohol propolis concentrations extract (AEP) (0.0, 0.5, 1.0 and 1.5gkg-1). The performance experiment period was conducted for 45 days. For the digestibility experiment, an inert marker in the feed and the adapted Guelph feces collecting system were used. The results showed no differences in the performance parameters, crude protein apparent digestibility and dry matter of the feeds, intestinal morphometry, and physiologic parameters. However, there was an increasing linear effect on the energy digestibility with increasing PAE concentrations in the fish feed. The usage of the propolis extract supplementation levels of 1% is recommended for optimum effect on villus morphometry in Nile tilapia.

Assessment of Water Recycling Effectiveness for a Super-Intensive White Leg Shrimp Farm in Ca Mau Province

Recycling shrimp farming water is a way to address the trend toward a circular economy in Vietnam's coastal regions while also reducing the quantity of effluent that is released into the environment. In order to explore the potential for waste recycling, this study investigates the pond system of a highly intense Littopenaeus vannamei culture area in Ca Mau province. The water balance approach was used to assess how effectively shrimp farms use water. In order to determine how much water helps to the financial success of shrimp farming, the value of water was also evaluated. According to the results of the water balance calculation, the current system could result in water losses of up to 1000 m3, accounting for over 20% the total water use. Only 33 m3 of water loss was estimated for the proposed water recirculation system, which was 3% of the current system. By recirculating the treated water back into the shrimp ponds, the farm also saved 20% of the water utilized for those ponds. The economic value of water was 6000 VND/m3 for the current farming system. The water value in the system would be decreased by 20% for the suggested treatment system. The high cost of investing in water recirculating technologies is related to the high water exchange rate. When deciding how much water to allocate, it should be taken into account.

The challenges of aquaculture in protecting the aquatic ecosystems in the context of climate changes

The paper discusses the current prognoses of aquaculture development worldwide putting an emphasis on its effect on the environment and the issue of the protection of water reservoirs in different countries. Water consumption in diversified aquaculture systems is presented herein as well as the characteristics of the mechanical and biological water treatment methods in fish farms, with particular attention paid to the recirculating water systems. New aquaculture technologies using post-production waters are presented. The paper provides a discussion on the contribution of aquaculture to the global greenhouse gas emissions and the means of limiting this emission. The effect of climate change on aquatic ecosystems is presented in the context of the changes of the aquaculture production profile. The paper includes a brief presentation of the methods of mitigating the changes with respect to contamination of aquatic ecosystems as well as climate change. Reducing the water footprint can be achieved through selective breeding, species diversification and implementation of more technologically advanced aquaculture systems such as: integrated multi-trophic aquaculture, aquaponics and recirculation systems in aquaculture. The need for certification of fish farms with water recirculation systems is justified in the paper. The issues addressed herein are summarised and the main areas for extending the research promoting preservation of aquatic ecosystems in aquaculture are presented.

Redox status of juvenile Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), fed diets supplemented with poultry liver protein hydrolysate as feed aditive

Plant ingredients, when used as substitutes for animal protein ingredients, can negatively influence fish growth. Thus, feed additives have been used to enhance feed consumption, nutrient utilization efficiency and stress tolerance under intensive management conditions. One such potential feed additive in aquafeeds is poultry liver protein hydrolysate (PLPH), which is rich in essential amino acids and has in vitro antioxidant and antibacterial properties. In this study, we aimed to evaluate the effect of poultry liver protein hydrolysate as feed additive on the productive performance of Nile tilapia reared in a water recirculation system and investigate stress responses and redox status after an air exposure challenge. Nile tilapia juveniles were randomly distributed in 24 aquariums and fed plant-based diets supplemented with increasing levels of PLPH (0, 10, 20, and 40 g/kg) over a 45-day period. At the end of the experiment, we did not observe a significant effect of PLPH on productive performance variables or body indices (P > 0.05). Air exposure triggered stress responses in fish, as evidenced by an increase in blood glucose (P < 0.05). However, PLPH supplementation did not mitigate this effect (P > 0.05). Regarding redox status, a quadratic effect of PLPH supplementation was observed on malondialdehyde (P = 0.003) levels, as well as the activities of superoxide dismutase (P = 0.015), catalase (P = 0.015), and glutathione S-transferase (P = 0.001). Optimum PLPH supplementation levels were estimated at 25.14, 25.91, 22.57, and 18.83 g/kg, respectively, for these redox parameters. Increasing PLPH levels decreased carbonylated protein contents (P = 0.001) but increased hydrogen peroxide levels in the gills (P = 0.006). Although PLPH supplementation improved antioxidant enzyme activity, and attenuated protein damage, it concurrently increased reactive oxygen species production and lipid peroxidation. Further studies are necessary to elucidate the underlying mechanisms of action by which protein hydrolysates influence the redox status of fish reared under intensive management.

EFFECT OF LARVAL DENSITY AND DIET ON THE GROWTH AND SURVIVAL OF Perna perna MUSSELS IN RECIRCULATION SYSTEM (RAS).

This study evaluated the effect of initial larval stocking density and microalgae concentration in the diet on the growth and the number of competent larvae (number of live larvae at the end of the experiment retained on a sieve with mesh size of 210 µm) of Perna perna in a water recirculation system (RAS). The experiment was conducted using a completely randomized design and factorial scheme, with one factor being the food concentration at three levels (low: between 1.26 to 2.19, medium: between 2.36 to 3.94 and high: 5.03 to 7.29 x 104 cells mL⁻¹) and the second factor being the larval culture density, also at three levels (20, 80 and 200 larvae mL⁻¹), with 3 replications in each treatment. Larvae fed with the diet with low and high concentrations did not reach competence (210 µm) in 16 days. However, for larvae fed with the medium concentration (2.36 to 3.94 x 104 cells mL⁻¹), the average percentage of competent larvae, on day 16, was 21.8% ± 7.45, 27.4% ± 9.91 and 0.80% ± 0.26 at the densities 20, 80 and 200 larvae mL-1, respectively.

Development of an automated mosquito pupae counter.

The production of mosquitoes for control programs or basic research is facilitated by the standardization of rearing conditions allowing the daily manipulation of thousands of individuals. It is crucial to develop mechanical or electronic systems for controlling the density of mosquitoes at each development stage with the aim of reducing costs, time, and human errors. We present herein an automatic mosquito counter using a recirculating water system allowing rapid and reliable counting of pupae without detectable increased mortality. Using Aedes albopictus pupae, we determined the density of pupae and the time of counting for which the device is most accurate, and evaluated the time saved using this device. Lastly, we discuss how this mosquito pupae counter can be useful in small-scale or mass-rearing contexts enabling a number of applications for research purposes as well as operational mosquito control programs.

The future of intensive tilapia production and the circular bioeconomy without effluents: Biofloc technology, recirculation aquaculture systems, bio‐RAS, partitioned aquaculture systems and integrated multitrophic aquaculture

AbstractModern tilapia farming with low use of water aims, as in circular bioeconomy, to reduce inputs and fully reuse waste and effluents, closing flows or links of economic and ecological resources and decentralizing production systems (local production and local consumption). Concerns over diseases, market demand for a clean, sustainable and ecologically correct aquaculture, with greater and more efficient controls, increased predictability and repeatability of activities, are leading to a series of structural changes in the reuse of water and effluents through various closed recirculation systems with the reuse of waste as nutrients. In recent decades, one of the most important innovations and trends of tilapia culture is towards circular bioeconomy, characterized in this review by several recirculation systems, such as biofloc technology (BFT), recirculation aquaculture systems (RASs), bio‐RAS, partitioned aquaculture systems (PASs with split ponds, SPs; and in pond recirculation system, IPRS) and integrated multitrophic aquaculture (IMTA). The future of tilapia culture meshes with urban agriculture and waste fermentation, where low‐demand water recirculation systems will be the protagonists in the disruption of industries in five main sectors (materials, energy, information, transport and food/health), that still today focus on extraction, into a more sustainable local model.

BUDIDAYA IKAN LELE DAN TANAMAN KANGKUNG MELALUI SISTEM BUDIDAYA AQUAPONIK DI DESA SIDORAHARJO KECAMATAN KEDAMEAN KABUPATEN GRESIK

Aquaponic cultivation is a technique that is very easy to implement in Sidoraharjo Village because it has narrow land. Aquaponics is an aquaculture activity that is integrated with hydroponic activities. developing two different commodities, fish and vegetables in a &#x0D; Maintenance system on narrow&#x0D; landAquaponic technology is a combination of aquaculture technology and hydroponic technology in one system to optimize the function of water and space as a rearing medium. The plants will receive organic Aquaponic technology is a combination of aquaculture technology and hydroponic technology in one system to optimize the function of water and space as a rearing medium. The plants will receive organic fertilizer automatically from the remaining feed and fish waste. The advantage of using aquaponic cultivation is that plant nutrients can be obtained from feces and leftover fish food that settles at the bottom of the pond, so that quality water is produced that meets standards for fish farming. The stability of dissolved oxygen in water will be obtained from a water recirculation system in the form of a shower that results in collisions with pool water. In addition, the production of plants cultivated with the aquaponic system will be better than conventional because of the availability of sufficient water and additional nutrients from fish feces and food scraps.

Upflow Anaerobic Floating Filter (UAFF) Improved the Performance of the Anaerobic Treatment of Brackish Aquaculture Waste

Highlights Fish hatchery RAS thickened wastewater was successfully treated by anaerobic digestion. Traditional complete mix digester (CSTR) configuration was compared to the UAFF, an upflow anaerobic floating filter. UAFF start-up resulted faster and more productive than in conventional reactors (188 compared to 100 NmL CH4/g VS). At steady conditions, yields of 190.5 and 180.9 NmL CH4/g VS were recorded, for UAFF and CSTR respectively. Abstract. Thickened wastewater from a fish hatchery recirculating water system (RAS) was successfully treated by anaerobic digestion, showing a high methane potential in brackish and marine conditions. To optimize the process and establish operational criteria for a full-scale transfer, pilot-scale tests were carried out in a BioReactor Simulator System (BRS, Bioprocesscontrol, Sweden). The BRS consists of 6 reactors with a volume of 1.8 L each: 3 reactors operated in conventional configuration (CSTR, continuous stirred tank reactor), while the other 3 were modified with an up-flow fixed bed layout, with floating plastic filling elements (UAFF, upflow anaerobic floating filter). The objective of the present paper was the comparison of the performance of the UAFF and the CSTR anaerobic systems both in the initial colonization batch process, and in the following continuous process. The batch test was performed in 72 days by treating aquaculture sludge inoculated with brackish digestate, for the CSTRs, and with the biofilm of the plastic media for the UAFFs. The following continuous loading phase was characterized by start-up and steady steps. The tests were performed in mesophilic conditions. The start-up in the UAFF reactors resulted significantly faster and more productive than in conventional reactors, with specific yields reaching 187.9 NmL CH4/g VS compared to 100.0 NmL CH4/g VS. During the following steady phase, with the retention time of 20 days, the specific yields increased in all digesters but the differences between the 2 types of reactors were not significant, even if favorable for the UAFF (190.5 and 180.9 NmL CH4/g VS, respectively for UAFF and CSTR). Keywords: Anaerobic digestion, Anaerobic filter, Aquaculture, Biogas, Biomethane, Brackish and marine wastewater, Fish farm effluents.

Evaluation of Disinfection Methods for Artificial Plants in Zebrafish (Danio rerio) Recirculating Water Systems.

The use of artificial plants as environmental enrichment for zebrafish (Danio rerio) in biomedical research facilities has been shown to provide benefits in animal welfare and care. Despite the benefits of artificial plants to zebrafish welfare, some research facilities are hesitant to incorporate them into their routine husbandry practices due to concerns about disease transmission and a lack of guidance on effective disinfection practices between tanks. Limited published information is available on how to adequately disinfect artificial plants, which creates concerns regarding their reuse between tanks in recirculating water systems. Proper sanitation and disinfection of these items is crucial to preventing the spread of disease in the system. We evaluated 2 disinfection methods- a commercial-grade laboratory glassware dishwasher and an ethylene oxide (ETO) sterilizer-by using ATP detection and bacterial culture of the artificial plants before and after the disinfection process. Plants were placed in the dirty sump of 2 separate recirculating systems (2,500 to 3,000 fish per system) for 2 wk before the start of the study. High ATP levels and various bacterial organisms were detected prior to disinfection. The commercial-grade labo- ratory glassware dishwasher and ETO sterilizer both significantly reduced ATP levels and resulted in complete eradication of live bacteria that were present before treatment. This study demonstrates 2 effective methods for disinfecting artificial plants in zebrafish facilities.

Incubating red NIFI strain of tilapia eggs in a closed-water recirculation system with varied salinity levels

This research aims to determine the impact of varying salinities on the hatching of red NIFI tilapia eggs in a closed-water recirculation system incubator. The eggs were hatched at salinities of zero ppt, one ppt, five ppt, and ten ppt, with three replications per treatment. The stocking density for each replication was set at 1,750 eggs per liter. After a six-day incubation period, the resulting larvae were reared under the same salinity conditions for four weeks, with a stocking density of 1,000 individuals per cubic meter. The hatching rate of eggs recorded for the zero ppt salinity treatment was 74%. There was no significant difference between the zero ppt, one ppt (73%), and five ppt (69%) salinity treatments, while the ten ppt (24%) yielded significantly different hatching rates of eggs results (p&lt;0.05). The highest survival rate of reared larvae was achieved in zero ppt salinity treatment, reaching 75%. Salinities of one ppt, five ppt, and ten ppt yielded larvae survival rates of 70%, 55%, and 49%, with statistical significance (p&lt;0.05). Egg hatching in an incubator with a closed water recirculation system at low salinity levels can be considered an initial adaptation step in brackish water tilapia seed production.

Solar Panel Automated Cleaning Using Water Re-Capture and Re-Circulation System

Abstract: Sun photovoltaic (SPV) module energy output is closely correlated with solar accessible irradiance, spectral content, and other factors including environmental and climatic factors. It is normal for dust from the outside environment to collect on solar photovoltaic (PV) system panels. Physical factors like rain, dirt, dust, snow, etc. can lower a solar panel's overall efficiency. So maintaining a clean solar panel is crucial. The performance of solar panels can be negatively impacted by collected dust, according to research, however, the results were not measured. This study's goal was to investigate how dust build-up affects the efficiency of solar PV panels. To test the electrical output and efficiency of solar panels, experiments were carried out utilizing dust particles on solar panels with a constant-power light source. The efficiency and resultant electrical power generated revealed it. According to the study, the effectiveness of a photovoltaic solar panel might be reduced by up to 30% by dust build-up on its surface. Therefore, it is crucial to clean the solar panel of any dust. We may clean the solar panels and improve their effectiveness by using the wiper on the water pump's base.

Valorization of chicken intestine: A process of protein hydrolysate for fish feed attractant using pilot plant scale system

Chicken intestine as a poultry industry byproduct is rich in protein, contains various endogenous enzymes and can be prepared as a hydrolysate via autolysis. This research examined the physicochemical properties of chicken hydrolysate as a feed attractant. Growth of fish fed on the chicken hydrolysate-coated diet was compared with fish fed on a commercial hydrolysate (C). Three chicken hydrolysates were prepared at 60 °C for 4 h on a pilot plant scale including autolysis at pH 3 (S1), supplemental enzyme addition at pH 6.11 (S2) and a combination of supplemental enzyme addition following autolysis at pH 3 (S3). Highest yield was found in S2 (76%) followed by S3 (74%) and S1 (72%). The chicken hydrolysate had lower protein content (13–16%), higher fat (21–23%) and lower viscosity at 7429–10607 cP compared with C. Degrees of hydrolysis (DH) of S1, S2, S3 and C were 56%, 73%, 65% and 61%, respectively. Highest number of peptides less than 3 kDa associated with feed palatability was found in S2 (76%), followed by S3 (49%), C (29%) and S1 (28%). The three chicken hydrolysates were rich in essential amino acids similar to the C sample but with smaller amounts of amino acids in S1 and S3 due to the acidic pH preparation. An 8-week feeding trial of two selected fish species (hybrid catfish and Nile tilapia) was conducted in a water-recirculation system to investigate the effect of different hydrolysate-coated diets on fish growth performance. Highest body weight of hybrid catfish at 65.20 g gave weight gain of 150.15% and specific growth rate 1.73% d−1. Optimal feed conversion ratio (FCR) at 1.49 was observed in the S2 diet (p < 0.05). Improved growth performance was observed in Nile tilapia for diets coated with all chicken hydrolysates but no significant difference was found (p ≥ 0.05). Highest values of the hematological parameters, including hemoglobin, hematocrit and mean corpuscular hemoglobin concentration, were found in the two fish groups fed with S1, S2 and S3 diets (p < 0.05). At the end of the experiment, hybrid catfish and Nile tilapia fed with the S2 and S3 diets had the highest fish body protein content at 17% and 16%, respectively (p < 0.05). Our results showed that the three chicken hydrolysates, particularly S2, could potentially be used as feed attractants for freshwater fish.

Performance and carcass yield of silver catfish raised in monosex and mixed-sex systems

Abstract - An experiment lasting 180 days was carried out to evaluate the influence of sex on the performance and production of silver catfish (Rhamdia quelen) when reared in closed recirculation systems using only males, only females, or with both genders. A total of 300 fish (41.49 ± 6.82 g and 16.53 ± 0.95 cm) were used, comprising 150 females and 150 males distributed in an experimental structure consisting of three closed water recirculation systems coupled to a 20,000 L culture tank and a 20,000 L biofiltration tank connected by a 3,500 L h-1 water pump. The first system contained 100 females, the second, 100 males, and the third, 50 females and 50 males. High fish weight variations were observed regardless of sex. Female weight gains and specific growth rates were 41.51 % and 28.94 % higher compared to males, respectively, exhibiting greater growth than males raised monosexually or in mixed rearing systems, with no effect on chemical composition or trunk yield. The findings thus indicate that both male and female silver catfish exhibit wide weight variations and females that gain more biomass than males reared monosexually or in mixed-sex systems.

Acoustic feeding responses using marine chemoattractants in plant-based diets for naive and non-naive Litopenaeus vannamei

The inclusion of chemoattractants has been investigated to improve the attractability and palatability of plant-based shrimp diets. A more recent approach utilizes passive acoustic monitoring (PAM) to record the sounds (clicks) emitted by shrimp during feeding activity allowing the identification of behavioral responses related to the diets. In the present study we automatically identified click signals in PAM recordings at sampling frequency of 192 kHz. This methodology was applied to evaluate the efficiency of three chemoattractants (krill meal, squid meal and fish hydrolysate) added to a basal all-plant diet on the acoustic feeding behavior and food consumption of naive (without acclimation) and non-naive (acclimated to the diets) Litopenaeus vannamei. Five diets were used: basal all-plant diet (AP, negative control) and its modifications to contain 20 g/Kg of krill meal (AP+KM), 20 g/Kg of squid meal (AP+SM) and 40 g/Kg of fish hydrolysate (AP+FH); a diet with 120 g/Kg fishmeal (FM) was used as a positive control. Ten shrimp (6.8 ± 0.6 g; mean ± SD) were stocked per aquarium (70 L) in a clear water recirculation system (30 aquaria, five diets with six replicates). The food consumption and acoustic activity were evaluated simultaneously in each aquarium over a 30-min period during two consecutive days for each trial, naive and non-naive shrimp. Strong positive relationships (r = 0.78–0.81; P < 0.001) were found between food consumption and total number of clicks emitted by naive and non-naive shrimp. Overall, the inclusion of the chemoattractants to the plant-based diet had a positive effect improving acoustic feeding behavior and food consumption for naive and non-naive L. vannamei. In particular, the response of non-naive shrimp to chemoattractants was markedly increased, and the highest clicking activity was attained by using krill meal (AP+KM), followed by fish hydrolysate (AP+FH). The new analytical method proved to be a useful alternative approach for studying shrimp feeding behavior, also indicating the potential of PAM to forecast feed intake and improve efficiency of feed management.

Mango extract in tambaqui (Colossoma macropomum) diet: an in vitro and in vivo study

ABSTRACT Two experiments were carried out in order to evaluate the functional effect of mango extract in vitro and in vivo. The in vitro assay evaluated the growth of Lactobacillus spp; different treatments with mango extract (1% and 3%), cellulose (1% and 3%) and a control group were used. In the in vivo test, 100 juvenile tambaquis were used, with an initial average weight of 57.03 ± 1.05 g, distributed in twenty 1000 L experimental units, in a water recirculation system with a biofilter. Five diets were tested, with different concentrations of mango extract (0, 20, 40, 60 and 80 g kg−1 of diet). The in vitro assay showed that the addition of 3% mango extract presented functional-prebiotic potential against the Lactobacillus spp. strain. The recommended concentration of 40 g. kg−1 of mango extract in the diet for tambaqui improves performance. Some hematological variables showed significant variations but did not harm tambaqui. Mango extract improved muscle glycogen stores. Plasma albumin and nonspecific alkaline protease activity were responsive in fish fed mango extract. Mango extract increases the lactate concentration in the tambaqui intestine.