Artemia Nauplii Research Articles

Comparative Toxicity Analysis of 3M ESPE Clinpro Tooth Crème and VOCO Profluorid Varnish in Artemia Nauplii and Zebrafish Larvae

Comparative Toxicity Analysis of 3M ESPE Clinpro Tooth Crème and VOCO Profluorid Varnish in Artemia Nauplii and Zebrafish Larvae

Effect of water temperature on the beginning of active feeding of tugun and nelma larvae

Temperature conditions of transition to active feeding of tugun Coregonus tugun (Pallas, 1814) and nelma Stenodus leucichthys nelma (Pallas, 1773) larvae to substantiate elements of artificial reproduction biotechniques were studied experimentally. We added live food (Artemia nauplii) and placed larvae a day after the transition to the first stage of the larval period in aquaria with different constant temperatures. The proportion of larvae that started feeding consistently increased in the temperature range 0.2–10 °C reaching 100% at daily exposure of experiments. The 50% level of transition to active feeding was observed at 6 °C. The ability of larvae with preliminary feeding experience to consume food at a temperature 1–5 °C lower than that of larvae that had not fed before was found. The individual duration of larvae transition to active feeding varied significantly from 1 to 8–9 days in a series of experiments at a stable low temperature (0.2 °C). Delayed initiation of exogenous feeding due to the limiting effect of low temperatures is physiologically equivalent to larval starvation. This may negatively affect the subsequent development of larvae. Species specificity was not significantly revealed in all series of experiments. We recommend keeping the water temperature at least 10°C from the time of embryo transition to larval development when rearing juveniles under intensive technologies to reduce the diversity of planting material in terms of size parameters. In this case, the duration of the time interval necessary for the beginning of active feeding of all larvae will be maximally reduced.

Feeding protocol for the Amazonian ornamental cichlid Apistogramma cacatuoides and a histological approach to the nutritional condition of larvae.

The aim of this study was to develop a feeding protocol for the larviculture of Apistogramma cacatuoides, using the histological approach to larval nutrition conditions. For this, three experiments were carried out. Experiment 1 was carried out in a randomized design to determine the optimal amount of Artemia nauplii (AN) per larva, and three treatments were evaluated: P1-feeding with 25 A. nauplii per larva (AN/L) during the first 5 days, followed by 50 AN/L from the 6th to the 10th day and 100 AN/L from the 11th to the 20th day; P2 and P3-37 and 50 AN/L during the first 5 days, 75 and 100 AN/L from the 6th to the 10th day and 150 and 200 AN/L from the 11th to the 20th day. Experiment 2 was carried out in a randomized design to determine the daily frequency of feeding and evaluated four feeding frequencies: F1-feeding only once a day (09:00); (F2)-feeding twice a day (09:00 and 17:00); F3-feeding three times a day (09:00, 11:30 and 17:00); and F4-feeding four times a day (09:00, 11: 30, 14:00 and 17:00). Experiment 3 lasted 40 days and was conducted in a randomized design to evaluate three periods for the beginning of the feeding transition: WE10:AN for 10 days, followed by 3 days of co-feeding and commercial feed until the end of the experimental period; WE15:AN for 15 days, followed by 3 days of co-feeding and commercial feed; WE20:AN for 20 days, followed by 3 days of co-feeding and commercial feed. The results of this study showed that, for the best development of the larvae, they should receive the feeding protocol 50-100-200 AN/L (P3) until the 20th day of exogenous feeding. From the 21st day, the transition to inert food should begin with 3 days of co-feeding, and feeding during larviculture should be carried out at a frequency of twice a day; this protocol provided a good nutritional status for the larvae, as shown by the histological approach.

The effects of diet, salinity and temperature on HUFA accumulation in Artemia

Artemia nauplii is an important live food item for marine fish and crustaceans. However, the HUFA content of Artemia from different origins varies greatly and is generally low. Compared with other species or strains, Artemia cysts in Tibet salt lakes have very high HUFA content, which may be related to their unique living conditions. This study determined the effects of dietary HUFA (P. tricornutum and C. zofingiensis), salinity (4%, 8%, and 12%), and temperature (14 °C, 19 °C, and 24 °C) on the HUFA accumulation of Lagkor Co Artemia tibetiana after 14-day culture, in comparison with Great Salt Lake Artemia franciscana. The results showed that the HUFA profile of Artemia was closely related to the dietary HUFA level, and the low temperature and low salinity could significantly increase the ARA, EPA, and DHA content. PCA results showed that the fatty acid distribution patterns of the two Artemia species were mostly affected by dietary fatty acids, which were greater than those of temperature, salinity, and Artemia species. RNA-seq analysis and qRT-PCR verification revealed that low temperature and low salinity could promote the gene expression of fatty acid binding protein gene, long chain fatty acid elongase, and desaturase, suggesting these genes may be involved in the process of HUFA accumulation in A. franciscana. In conclusion, diet is a key factor affecting HUFA accumulation in Artemia, while low temperature and low salinity led to higher HUFA retention. The findings of this study provide a reference for revealing the mechanism of HUFA synthesis and metabolism of Artemia, and to develop the Artemia products with high HUFA content through manipulation of culture conditions.

Neuropeptide Y receptor Y8b (npy8br) regulates feeding and digestion in Japanese medaka (Oryzias latipes) larvae: evidence from gene knockout.

Neuropeptide Y receptor Y8 (NPY8R) is a fish-specific receptor with two subtypes, NPY8AR and NPY8BR. Changes in expression levels during physiological processes or in vivo regulation after ventricular injection suggest that NPY8BR plays an important role in feeding regulation; this has been found in only a few fish, at present. In order to better understand the physiological function of npy8br, especially in digestion, we used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology to generate npy8br-/- Japanese medaka (Oryzias latipes). We found that the deletion of npy8br in medaka larvae affected their feeding and digestion ability, ultimately affecting their growth. Specifically, npy8br deficiency in medaka larvae resulted in decreased feed intake and decreased expression levels of orexigenic genes (npy and agrp). npy8br-/- medaka larvae fed for 10 d (10th day of feeding) still had incompletely digested brine shrimp (Artemia nauplii) in the digestive tract 8 h after feeding, the messenger RNA (mRNA) expression levels of digestion-related genes (amy, lpl, ctra, and ctrb) were significantly decreased, and the activity of amylase, trypsin, and lipase also significantly decreased. The deletion of npy8br in medaka larvae inhibited the growth and significantly decreased the expression of growth-related genes (gh and igf1). Hematoxylin and eosin (H&E) sections of intestinal tissue showed that npy8br-/- medaka larvae had damaged intestine, thinned intestinal wall, and shortened intestinal villi. So far, this is the first npy8br gene knockout model established in fish and the first demonstration that npy8br plays an important role in digestion.

Characterization and investigation of biofabricated ZnO nanoparticles using Caulerpa sertularioides for antioxidant and antibacterial purposes

Nanoparticles synthesized from marine macroalgae have garnered significant attention in biomedical research due to their potential applications. In this study, zinc oxide nanoparticles (ZnO NPs) were synthesized using an extract from Caulerpa sertularioides (Cs) as a reducing agent. The synthesized C. sertularioides-mediated zinc oxide nanoparticles (Cs-ZnO NPs) were characterized by UV–visible spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), High-resolution transmission electron microscopy (HR-TEM), and Dynamic light scattering (DLS) techniques. In the UV–visible spectroscopy analysis, the maximum absorption peak was observed at 364 nm. XRD analysis confirmed that the Cs-ZnO NPs had a crystalline structure. FE-SEM and HR-TEM demonstrated that the Cs-ZnO NPs were mostly spherical in shape and the size ranged between 20 and 87 nm. The zeta size and potential of Cs-ZnO NPs at 97.89 nm and 14.1 mV were confirmed by DLS analysis. The antioxidant activities were tested by various in vitro assays, and the results demonstrated that Cs-ZnO NPs exhibit dose-dependent antioxidant activities. Further, Cs-ZnO NPs were highly effective against Vibrio harveyi both as an antibacterial and anti-biofilm agent. The toxicity assessment of Cs-ZnO NPs on Artemia nauplii indicated moderate toxicity. Overall, this study concludes that Cs-ZnO NPs have potential application in the aquaculture industry to prevent pathogenic illnesses and enhance disease resistance without causing adverse effects.

Not all that glitters is gold: Glitter causes acute toxicity to nauplii of Artemia sp.

Glitter has been reported as a relevant pollutant, as it is widely used in cosmetic and textile products and craftwork, and often associated with domestic sewage. The particular glitter is composed of thin layers of plastic and metal. This study assessed the acute toxicity of glitter dispersions in the brine shrimp Artemia sp. Nauplii of Artemia sp. that were exposed to glitter dispersions (0.01, 0.1, 1, 10, and 100 mg/L), obtained by diluting a stock solution in seawater; the control consisted of filtered seawater only. Three replicates were used per treatment and consisted of glass tubes filled with 10 mL of the test solution, and ten nauplii aging over 48 h. After 48 h, the survivors were counted and examined under a microscope. The mean size of glitter particles was 3.94 (±0.98) µm; approximately 44 % of particles were in the range of very fine sand, and 27 % coarse silt. Significant lethal effects (p < 0.05) occurred from 0.1 mg/L (Lowest Observed Effect Concentration - LOEC); the lethal concentration to 50 % organisms (LC50-48h) was 0.350 (0.348 - 0.351) mg/L. The exposed organisms also exhibited patches in their digestive tracts, and particles were stranded in their appendices. The results indicate the toxic potential of glitter to brine shrimp. This investigation indicates the need for further studies on the toxicity of glitter to marine invertebrates. Highlights Glitter includes particles of sizes similar to those of marine microalgae Exposure to glitter suspensions caused toxicity in brine shrimps from 0.1 mg/L The nauplii of Artemia were more sensitive to glitter than echinoderm embryos Metallic parts of the glitter were observed in the digestive tract of the brine shrimp nauplii

Effects of temperature and live prey concentration on Colossoma macropomum larviculture

Objective. The study evaluated the performance and survival of Colossoma macropomum larvae at different temperatures and concentrations of prey. Materials and methods. Two temperatures (28 and 32ºC) (T) and two initial daily concentrations (500 and 1,000 Artemia nauplii per larva) (CP) of prey were used. These concentrations were increased every 5 days during the first 15 days of cultivation. From the 16th to the 30th day, the larvae received exclusively a commercial diet. Results. In the first 7 days, weight (P), total length (TL) and daily specific growth rate (SGR) were higher for T32 treatments (p<0.05). After 15 days, P, TL and SGR were higher for CP1000 (p<0.05). After 22 days, P and TL suffered the effect of the initial concentration of prey and water temperature with higher values for CP1000 and T32 (p<0.05). At the end of 30 days of cultivation, P was affected only by water temperature with higher values for T32 (p<0.05). The TL showed an effect of temperature and initial concentration of prey with higher values for CP1000 and T32 (p<0.05). During feeding with a commercial diet (days 16-30 of cultivation), survival was higher for T32 (94.38±6.12%) (p<0.05), with no difference for initial prey concentration. Conclusions. It is concluded that the larviculture of C. macropomum must be carried out with a temperature of 32° C and that the food management must be differentiated during the first 15 days, positively influenced in the period of feeding with ration.

The Use of Acartia tonsa Nauplii during the First Days of Feeding on the Ontogeny of the Digestive System of Greater Amberjack (Seriola dumerili Risso, 1810)

The effect of feeding greater amberjack with copepod nauplii (Acartia tonsa) on the ontogeny of the digestive system was observed until 40 days after hatching (DAH). Copepods are part of the diet of fish larvae in nature, and they are rich in highly unsaturated fatty acids and free amino acids that enhance the digestive capacity of the fish. In a marine hatchery, four cylindroconical tanks of 2,700 L were stocked with about 150 × 103 greater amberjack larvae (Seriola dumerili) in each. The larvae were initially fed from 3 to 17 DAH in two tanks with copepod nauplii and rotifers (Brachionus sp.; Copepods group), while in the other two tanks, they were fed only with rotifers (Control group) during the same period. All the tanks were fed with rotifers (3–27 DAH), Artemia nauplii (12–22 DAH), enriched Artemia metanauplii (20–30 DAH), and formulated diet (25–40 DAH). Fish samples were taken regularly (every 2 or 4 days) for histological analysis and every day for the measurement of total length (TL). The TL was 3.7, 4.5 ± 0.1, 6.1, 11, 17.3 ± 0.1 and 20.3 ± 2.3 mm at 4, 10, 16, 22, 30, and 40 DAH, respectively. Copepod-fed fish showed higher TL in the last 2 days of the trial (p <0.05), while mortality rates were lower in the beginning of the trial 10–17 DAH, (p <0.05). In addition, copepods-fed fish had less skeletal deformities (p <0.05). Pyloric caeca appeared earlier in the Copepods group compared with the Control, while the length and surface of the villi, the abundance of goblet cells/100 μm of intestine length, and the area covered with lipid vacuoles in the liver were significantly higher in the Copepods group (p <0.05). We can conclude that the use of copepods in the diet of the greater amberjack larvae can improve the ontogeny of the digestive system.

Early ontogeny of the African bony-tongue (Heterotis niloticus) and the effect of Artemia and rotifer live feeds on larval digestive enzyme activity and performance

High larval and fry mortality has been a major challenge to the commercial culture of the African bony-tongue (Heterotis niloticus). Research indicates inadequate feeding to be a possible cause of the high mortality rates of larvae/fry grown in captivity. An experiment was conducted to first describe the developmental stages of H. niloticus eggs and larvae until schooling, 6 days after hatching (DAH), at 26°C. The morphological development, survival, growth (weight gain and length), and swimming behavior of the larvae were monitored. A follow-up feeding trial was conducted with H. niloticus fry from 6 to 27 DAH involving four treatments: feeding with Artemia nauplii; a combined feed of 50% Artemia nauplii and 50% rotifers (w/w); feeding with rotifers; and no feeding. The activities of three digestive enzymes (trypsin, lipase, and amylase) were assessed in fry exposed to the live feed treatments. At hatching, the larvae had a large, vascularized yolk sac filled with yolk platelets, which occupied approximately one-third of the total body length of the abdominal cavity. Yolk platelet reabsorption started at 1 DAH and was complete at 6 DAH. Metamorphosis was completed at 6 DAH, and schooling behavior was observed. For the feeding trial, the fry that received Artemia nauplii underwent the fastest development until 27 DAH. Similarly, the survival rate was considerably higher in fry fed with Artemia nauplii than in those that received a combination of Artemia nauplii and rotifers or only rotifers. Overall, the survival rates for fry fed with Artemia nauplii and larvae co-fed were 72.7% ± 0.9% and 41.2% ± 3.3%, respectively. Fry did not survive until 27 DAH in the rotifer-fed and unfed treatment groups. Digestive enzyme activity differed significantly (p< 0.05) between treatments and sampling dates. All digestive enzymes were detectable at the onset of mouth opening (5 DAH) and fluctuated through the 7 and 9 DAH. Lower enzyme activity was observed when the fry were subjected to starvation or the rotifer treatment. Results indicate that Artemia nauplii is the best live feed organism for H. niloticus larviculture.

Larval digestive system ontogeny and early weaning in neon tetra Paracheirodon innesi.

The intensive culture of characid teleosts for ornamental trade is highly dependent on live feed organisms, particularly Artemia nauplii, to provide nutrition through the larval stage. Live feeds have inherent disadvantages relative to prepared microparticulate diets (MDs), specifically availability, labor and cost. In this research, the dependence of larval Paracheirodon innesi on live Artemia was confirmed via a nutritional trial. Next, digestive system ontogeny was characterized from the onset of exogenous feeding through metamorphosis. P. innesi exhibited an agastric larval stage, as well as low digestive enzyme activity at the onset of exogenous feeding followed by abrupt increases in trypsin, lipase and pepsin activity. Differentiation of the stomach, including gastric gland formation and production of neutral mucopolysaccharides, as well as the onset of pepsin activity, did not occur until 20days post hatch (dph; 5.24 ± 0.20mm). This shift from agastric to gastric digestive modes is indicative of a proliferation of digestive capacity and subsequent prey diversity in other fish species exhibiting similar altricial larval stages.Based on this information, different schedules for weaning from Artemia to a MD were evaluated. For P. innesi fed until 32 dph, weaning beginning at 12 dph and 17 dph resulted in similar survival to live Artemia (mean: 22.0 ± 1.7%), and the MD resulted in the lowest survival (0.8 ± 0.3%). These results indicate that weaning is possible prior to gastric differentiation, potentially resulting in the reduction of Artemia use in the larval culture P. innesi.

Laboratory evaluation of the effects of Portunus pelagicus extracts against Culex pipiens larvae and aquatic non-target organisms

Culex pipiens (Diptera: Culicidae) is a pathogen-bearing mosquito found worldwide. Marine organisms are a promising source to search for mosquito-killing substances. The potential of the different solvent extracts of Portunus pelagicus was examined using Cx. pipiens 3rd instar. The bio-safety evaluation was carried out using Danio rerio (zebrafish) and Artemia nauplii (brine shrimp). The larvicidal activity of Portunus pelagicus (blue crab) was found in chloroform extracts against Cx. pipiens 3rd instars, with LC50 value of 109.11 and LC90 value of 88.44 ppm after 48 h of treatment. A Biosafety assessment of P. pelagicus methanol extract on D. rerio and A. nauplii revealed that the extract had toxic effects on A. nauplii but was safe for D. rerio. However, the non-toxicity of the extract towards D. rerio may be misleading; further investigation on other aquatic organisms is required. Thus, the extract should be used with caution.

The effect of copepod Acartia tonsa during the first days of larval rearing in skeleton ontogeny and skeletal deformities in greater amberjack (Seriola dumeliri Risso, 1810)

The effect of feeding greater amberjack (Seriola dumerili) with copepod nauplii (Acartia tonsa) on osteological development was observed until 35 days after hatching (DAH). The skeletal deformities were observed at the end of the trial. Copepods are the natural food of marine fish larvae, and they are rich in highly unsaturated fatty acids and free amino acids. In a commercial marine fish hatchery in Greece (Galaxidi Marine Farm S.A.), four 2700 l cylindroconical tanks were stocked with amberjack yolk-sac larvae at a density of about 55 larvae/l. The larvae were initially fed from 3 to17 DAH in two tanks with copepod nauplii and rotifers (Brachionus sp.) (Copepods group), while in the other two tanks, only with rotifers (Control group). After 12 DAH, all the tanks were also fed with rotifers (3–27 DAH), Artemia nauplii (12–22 DAH), enriched Artemia metanauplii (20–30 DAH), and formulated diet (25–30 DAH). Fish samples were taken every three days, fixed in phosphate-buffered 5% formalin (pH = 7.2). Bone and cartilage were stained with alizarin red and alcian blue, respectively. Specific meristic characters were chosen to compare the first appearance and the completion of the formation of a structure as well as the completion of the calcification between the two rearing protocols (Copepods - Control), correlated with total length data. These meristic characters included replacement and membranous bones from the vertebral column and all the fins. The ontogeny of the meristic characters was observed earlier in fish larvae from the Copepods group compared with the Control, and for most of the meristic characters, these differences were significant (p < 0.05). TL50 data analysis was performed, and the results were similar. At the end of the trial, 35 DAH sixty fish from each tank were sampled for the analysis of skeletal deformities. A higher number and more significant deformities were observed in the Control group compared with the Copepods group (p < 0.05). In conclusion, the use of copepod nauplii during the first feeding period of greater amberjack had a positive effect on the osteological development and skeletal deformities of the larvae.

Influence of Various Live Feeds on Survival And Intermoult Duration of the Larvae of the Edible Crab, &lt;i&gt;Thalamita Crenata&lt;/i&gt; (Latreille)

Complete development with 92% survival was observed when the larvae were fed with the mixed diet (DE) of Coscinodiscus sp. and Artemia nauplii in 23.18 days, which was followed by Artemia nauplii (E) alone (89.6%) in 24,95 days, Coscinodiscus sp. (D) alone (2.1%) in 29.11 days, the mixture (ABCDE) of Thalassiothrix longissima, Nitzschia sp., Skeletonema sp. Coscinodiscus sp., and Artemia nauplii (90%) in 25.22 days and the mixture (CD) of Skeletonema sp. and Coscinodiscus sp. (25.6%) in 29.66 days. Incomplete development was observed i.e. upto third zoeal stage, when larvae fed with Thalassiothrix longissima (A) and Nitzschia sp. (B) (12% and 18%) in 12.6 and 14.05 days, respectively. It was followed by Skeletonema sp. (C) and mixture of Thalassiothrix longissima and Nitzschin sp. (AB), Skeletonema sp. and mixture of Thalassiothrix longissima, Nitzschia sp. and Coscinodiscus sp. (ABCD) (16.6%, 13.3% and 18%) in 16.09, 18.77 and 13.64 days, respectively, in which the development is only upto fourth zoeal stage.

Changes in digestive enzyme activities during the early ontogeny of milkfish, Chanos chanos larvae.

Knowledge of the developmental ontogeny of the digestive system and nutritional requirements of marine fish larvae is a primary requisite for their successful rearing under an optimal feeding regime. In this context, we assessed the activity profile of key digestive enzymes viz., trypsin, chymotrypsin, leucine aminopeptidase, lipase, amylase, and alkaline phosphatase during the early ontogeny of milkfish, Chanos chanos (0 day, 3 days, 6 days, 9 days, 12 days, 15 days, 18 days, 21 days, 25 days, and 30 days post-hatch). Larvae for this study were obtained from the successful breeding of milkfish at ICAR-Central Institute of Brackishwater Aquaculture, India. Growth curves (length and weight) of the larvae indicated a positive morphological development under a standardized feeding regime that comprised Chlorella salina, Brachionus plicatilis, Artemia salina nauplii, and commercial weaning feed for different larval stages. With respect to protein digestion, the specific activity of pancreatic enzymes trypsin and chymotrypsin and intestinal brush border leucine aminopeptidase showed two peaks at 3 dph and 15 dph, following the introduction of rotifer and Artemia nauplii. Similar bimodal peaks were observed for alkaline phosphatase and amylase activities, with the first peak at 3 dph and the second peak at 18 dph and 21 dph, respectively. Whereas in the case of lipase, high activity levels were observed at 0 dph, 3 dph, and 18 dph, with subsequent decreases and fluctuations. Overall, as most of the enzymes were found to have peak activities at 15 to 21 dph, this period can be potentially considered as the developmental window for weaning larvae from live to formulated feeds in milkfish hatcheries.

EFFECT OF DIFFERENT LIGHT INTENSITIES ON GROWTH AND DEVELOPMENT OF ARTEMIA (ARTEMIA SALINA) IN AN ARTIFICIAL ECOSYSTEM

Artemia nauplii are the best initital food for most fish larvae. Feeder fish, Artemia nauplii, contain the ingredients necessary for the survival of aquatic organisms during critical periods of early postembryonic ontogenesis. Thus, it is important to improve the biotechnology of Artemia cultivation in artificial ecosystems.&#x0D; Materials and Methods. In the course of the study, various illumination modes were used, namely, 1.5; 2.5 and 4 klx to determine the most effective one.&#x0D; Results. Various illumination modes affect Artemia development in different ways. The most effective illumination mode at the stage of embryonic development and the initial stages of postembryonic ontogenesis was 4 klx.

Effects of Different Feeding Regimes on Growth Performance, Survival Rate, Carcass Composition, Fatty Acids Profile, and Digestive Enzyme Activities of Great Sturgeon (Huso huso Linnaeus, 1758) Larvae

Six different feeding regimes (FR) were tested from 7 to 38 days post hatching (dph). Five thousand four hundred larvae (7 dph, 0.048 g) were randomly stocked in 18 fiberglass tanks contained 100 L fresh water (300 larvae per each tank). In larvae fed with FR-B, includes Artemia nauplii (AN) + Artemia biomass (AB) + microdiet (MD), the body weight (BW) at the end of trail (38 dph) similar the FR-D (AN + CHL + AB + MD), and E (AN + CHL + AB), was at high level. Survival rate was higher in larvae fed FR-A includes AN + chironomid larvae (CHL) + MD, but had a lower BW ( p &lt; 0.05 ). Moderate BW and survival rate were detected in larvae fed FR-C (AN + DP + MD). Larvae fed only MD (FR-F), had the lowest survival and the highest BW ( p &lt; 0.05 ). Different FR had a significant effect on crude protein (CP), crude fat (CF), ash, and dry weight ( p &lt; 0.05 ). The larvae fed FR-C and D had the highest CP ( p &lt; 0.05 ). The highest CF and ash in larvae were detected in FR-F and C, respectively ( p &lt; 0.05 ). Larvae from FR-A and B had higher levels of n−3 long chain polyunsaturated fatty acids in comparison with others FR ( p &lt; 0.05 ). The use of AB and CHL can increased the weight and survival rate of larvae, respectively. At the end of trail, the activity of pepsin, trypsin, lipase and α-amylase enzyme levels were lower in FR-B and F than others FR. Totally, by using a combination of AN + CHL + AB + MD had better results than others and ordered to H. huso larvae feeding. Using MD alone, can cause lesser development of the digestive system and little attractiveness, therefore it can cause starvation, and the empty digestive tract of larvae.

Suitability of Different Live Feed for First Feeding of Freshwater Fish Larvae

First feeding of many fish larvae depends on live feed. A comparative investigation on the effectiveness of different types of live feed is not available to our knowledge. Hence, we conducted a study to examine the effect of different types and combinations of live feed on the performance (survival rate, total length, body width, body mass, malformation rate) of pikeperch, Sander lucioperca, larvae. From day 0 (onset of exogenous feeding) to day 10, the saltwater rotifer Brachionus plicatilis, the freshwater rotifer Brachionus calyciflorus, the ciliate Paramecium bursaria, copepods (nauplii and copepodites) from a lake population, and Artemia nauplii were tested. Feeding with B. plicatilis, B. calyciflorus, and P. bursaria resulted in high survival rates of 80% and a homogenous and significant growth (increase in total length of 50% and in body width of 20%). As follow-up feed, copepod nauplii and Artemia nauplii were tested from day 11 to day 20. Copepod nauplii were superior to Artemia nauplii, as larvae fed with copepods showed higher survival rates (67–70% versus 38–47%) and a more homogeneous growth. A switch from seawater live feed to freshwater live feed or vice versa resulted in decreased survival rates. Therefore, a feeding regime consisting of B. calyciflorus or P. bursaria followed by copepods is considered optimal as first feed of pikeperch. The malformation rate was not affected by the tested feeding regimes. To investigate the wider applicability and transferability of these findings, complementary investigations were performed on burbot, Lota lota, and the freshwater whitefish Coregonus atterensis. The feeding regimes used for S. lucioperca larvae were also suitable for Lota lota. Moreover, L. lota could be fed with lake copepods from the onset of exogenous feeding. For C. atterensis, initial feeding with B. plicatilis, B. calyciflorus, or P. bursaria had no positive effects. Feeding with copepods from the onset of exogenous feeding was optimal considering survival rate and growth. Therefore, optimal first feeding regimes are very species specific and should be established for each new species.

Different Animal Metabolism Markers for Artemia Nauplii in Crude Protein Digestibility Assay for Lophiosilurus alexandri Larvae

This work aimed to develop a methodology for marking Artemia with different markers and evaluating their passage rate and digestibility in Lophiosilurus alexandri larvae of different ages. In the first phase, Artemia nauplii were marked 28 h after hatching with chromium oxide, titanium dioxide and NANOLIPE®. Contact times with the markers were 30, 60, 90 min at a concentration of 500 mg/L. Titanium dioxide had a higher concentration in Artemia than the other markers. The passage rate did not differ significantly between titanium and NANOLIPE®. In the second phase, the apparent digestibility of the protein in Artemia nauplii was evaluated for L. alexandri larvae at three ages. Average real protein digestibility at the three ages was 95.08%, demonstrating Artemia as a good quality food. All ages exhibited the same final time of fecal excretion of 30 min after feeding. Artemia nauplii presented satisfactory results for assimilation for all markers tested. In determining the digestibility of Artemia protein, we can conclude that chromium oxide and NANOLIPE® were good markers of animal metabolism and titanium dioxide was the worst marker of Artemia digestibility for the initial stages of L. alexandri.

Biogenic Synthesis of Silver Nanoparticles Using Pantoea stewartii and Priestia aryabhattai and Their Antimicrobial, Larvicidal, Histopathological, and Biotoxicity Potential.

In recent years, green nanotechnology has gained considerable importance for the synthesis of nanoparticles due to its economic viability and biosafety. In the current study, silver nanoparticles were synthesized using two bacterial isolates, H2 and H3, which were isolated from soil samples collected from the Western Ghats, Tamil Nadu, and identified at the species level as Pantoeastewartii (H2) and Priestiaaryabhattai (H3) by sequencing their 16s rRNA genes. Intracellularly synthesized silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and particle size analysis. AFM studies show that both of the bacterial synthesized Ag NPs were circular-shaped and disaggregated, with an average size distribution of 4 nm for Pantoeastewartii and 3.6 nm for Priestiaaryabhattai. Furthermore, their larvicidal activity, antimicrobial, histopathological, and biotoxicity effects were determined. The synthesized Ag NPs exhibited potent larvicidal activity against fourth instars of Ae.aegypti, An.stephensi, and Cx.quinquefasciatus exposed to a 50 µg/mL concentration for 24 h based on their LC50 and LC90 values. Histopathological studies of the affected mosquito larvae clearly show damage to the epithelial cells, food bolus, basement membrane, muscles, and midgut parts. The maximum antimicrobial activity of Priestiaaryabhattai-synthesized Ag NPs was observed for Streptomyces varsoviensis MTCC-1537, and that of Pantoea stewartii-synthesized Ag NPs was against Escherichia coli MTCC-43. The toxicity test on non-target organisms such as Artemia nauplii and zebrafish embryos indicates no visible abnormalities or mortality after their exposure for 48h. It is concluded that silver nanoparticles can easily be synthesized using Pantoea stewartii (H2) and Priestia aryabhattai (H3) as capping and reducing agents. Silver nanoparticles showed potent larvicidal activities and could potentially be used in integrated vector control programs because they are safe for other inhabitants of the same aquatic environment as mosquito larvae.