Enriched Artemia Research Articles

Impact of Feeding Artemia franciscana Enriched with Various Oil Resources on Growth, Blood Biochemical and Behavioral Indices, and Survival of Oreochromis Niloticus

Abstract The main objective of the present trial was to examine the efficacy of feeding tilapia fry fish on Artemia franciscana diets supplemented with various oil emulsion resources in terms of performance, behavior indices, survival rate, blood biochemical parameters, and immunological response. Four hundred Nile tilapia fry (weighing 0.15±0.05 g and measuring 2.17±0.08 cm) were randomly allocated into four equal groups (each with five repetitions) and acclimatized for fifteen days. The first group served as the control and received unenriched Artemia franciscana (G0), while the remaining three groups were fed Artemia franciscana diets enriched with different oil resources (0.5 mL oil per liter for 6 hours): soybean oil (G1), sesame oil (G2), and rice bran oil (G3). Behavioral observations were recorded during the 45-day experimental period. At the end of the feeding trial, the chemical composition and fatty acid content of both Artemia and fingerlings were analyzed. Furthermore, the growth performance, survival, and immune response of the fingerlings were evaluated. The results indicated noticeable improvements in behavioral measurements (feeding, foraging and schooling), performance (final length, final weight, net weight gain, feed conversion ratio and specific growth rate), survival, and immune response among fry fish supplemented with enriched Artemia, particularly those enriched with soybean oil. Additionally, the chemical composition and fatty acid content of both Artemia and fish fry were significantly enhanced when oil emulsions are applied, with soybean oil demonstrating the most prominent improvements. Whereas, supplementing fry fish Artemia diets with oil resulted in lower liver enzyme activity and higher protein component levels in plasma in comparison to the control group. In brief, feeding Nile tilapia fry fish Artemia diets enriched with a soybean oil emulsion (0.5 mL/L) is recommended for promoting high performance, immunological activity, and survival throughout the early stage till fingerlings phase.

Effects of selenium nanoparticles on larval development, ontogeny of antioxidant enzymes and fatty acid profile in Arabian yellowfin seabream (Acanthopagrus arabicus)

Selenium (Se) is an essential trace element that has vital effects on growth, antioxidant capacity and early development in marine fish larvae. However, traditional livefoods such as rotifer and artemia lack of Se. In this regard, a 50-day feeding experiment was conducted in order to examine the effects of Rotifer and Artemia enrichment with selenium nanoparticles (SeNPs) on growth, antioxidant capacity and fatty acid profile of Arabian yellowfin seabream (Acanthopagrus arabicus) larvae. Four levels of SeNPs were used to prepare the experimental emulsions,including control (0), 0.5, 1.0 and 5 mg SeNPs L−1. Larvae were stocked at density of 50 larvae L−1 into twelve 250-L cylindrical tanks. Tanks supplied with seawater (23 ± 1 ºC; 40.0 ± 1.0 g L−1). Green water was used from day first until 20 days after hatch (DAH). Rotifers (15 ml−1) were offered to larvae from day 2–21 DAH and Artemia metanauplii (1–3 Artemia ml−1) were offered to larvae from day 18–45 DAH. Fish were sampled at 0, 7, 10, 15, 22, 30, 40, 45, 50 DAH. The Se concentration in the livefoods and larval whole body linearly increased with the increment of SeNPs level in the experimental emulsions. Larvae wet weight showed quadratic response and increased with SeNPs up to 1 mg mg SeNPs/L, then decreased in SeNPs (5.0) group. The activity of antioxidant enzymes including catalase, superoxide dismutase glutathione peroxidase, and total antioxidant capacity increased but malondialdehyde level decreased in larvae fed the SeNPs-enriched livefoods and showed both linear and quadratic responses. Lysozyme activity in the whole body of larvae fed SeNPs-enriched livefoods had both linear and quadratic responses and in the most of the sampling times was higher than the control group. Docosahexaenoic acid (DHA) level in the livefoods and larval whole body increased with SeNPs. In conclusion, livefoods enrichment with SeNPs at 1 mg L−1 is recommended to elevate the antioxidant capacity and non-specific immune response in A. arabicus larvae.

A blend of microalgae and cyanobacteria produced from industrial waste outputs for the enrichments of Artemia salina: Effects on growth performance, antioxidant status and anomalies rate of European seabass (Dicentrarchus labrax) larvae

The recent fast development of the microalgae-related biotechnologies has enabled the availability of sustainable and nutrients-rich raw materials to be used as substitution of conventional sources in aquafeed formulation. However the cost of energy of the photobioreactors used to produce these microorganisms still constrained their wider inclusion into aquafeed compounds. By exploiting industrial waste outputs, Nannochloropsis sp. and Spirulina sp. were produced and utilised to formulate two experimental enrichments (LM1 and LM2). During a 60 days trial, their efficacy have been tested as Artemia metanauplii enrichments in the diet of European seabass (Dicentrarchus labrax) larvae, in comparison to a commercial control. Larvae were fed with isonitrogenous and isolipidic dietary treatments. Each dietary treatment presented a specific profile for the long chain polyunsaturated fatty acids ARA, DHA and EPA. Ratio of DHA/EPA in enriched Artemia of 4:1 as in the case of LM1 and LM2 in the presence of 1.4% of ARA (as a % on total fatty acid) guaranteed equal results to the control which displayed a ratio of DHA/EPA of 2:1 with 2.2% of ARA. No significant effects of the dietary treatments were detected in final survival, growth performance and incidence of skeletal anomalies. Regarding oxidative status, larvae fed with LM2 enrichment presented lower catalase activity than control larvae with no signs of oxidative damage, suggesting a potential antioxidant effect of LM2. The present study contributes to expanding the existing literature on successful utilisation of microalgae and cyanobacteria, used to produce valuable nutrients, in a perspective of circular nutrients economy.

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.

Performance Parameters of Paralarvae and Postparalarvae Rearing of Patagonian Red Octopus, Enteroctopus megalocyathus, under Experimental Conditions

Patagonian red octopus, Enteroctopus megalocyathus, an interesting species for Chilean aquaculture diversification, requires the improving of their experimental technology to obtain early juveniles. The first objective of the study was to enhance aspects of feeding and temperature management in broodstock, egg incubation, paralarvae rearing, and early juveniles’ growth. The results indicated that female weight decreases up to 46.0 ± 8.6% during the egg incubation. Test of 8, 14, and 18°C during egg incubation shows that at 18°C embryos do not survive. Paralarvae reared under four diet treatments: (1) unfed, (2) enriched Artemia (Nannochloropsis sp.), (3) copepod (Acartia spp.), and (4) juvenile crabs (Petrolisthes spp.) showed survival quadruplication when they fed copepods and crabs instead of Artemia. Juveniles reared at 11, 13, and 15°C improved feed conversion and protein efficiency ratios at 15°C. The second objective was to analyze batches of paralarvae and early juveniles of two different periods to obtain their performance indicators and to compare them between productive periods. The results of growth rates, the relative weight condition coefficient, and morphometric relationships are discussed in the context of paralarvae culture from 1 to 90 days after hatching (DAH) and early juveniles from 1 to 135 days postsettlement (DPS).

Effects of enriched Artemia urmiana with polyunsaturated fatty acids and vitamin C on reproductive performance and larval temperature stress resistance of Severum Heros severus

ABSTRACT The influence of enriched adult Artemia urmiana with essential fatty acids (EFA) and vitamin C on aquarium-raised Severum Heros severus reproductive performance, larval resistance to high temperature stress (34°C), and intervals between each spawning were determined. Broodstock were fed with formulated pellet diet (P), P + adult Artemia, Artemia + EFA (30%), Artemia + EFA- +0.5 g vitamin C and Artemia + EFA +1 g vitamin C for 10 weeks. Results indicated that enriched Artemia with EFA + 1 g vitamin C had significantly higher larval resistance to high temperature, and shorter intervals for the eight spawning cycles than the other experimental diets. Artemia + EFA +0.5 g vitamin C resulted in higher fertilization and hatching rates than the other treatments. Our results indicated that feeding live feed reduced the whole time for the eight spawning cycles, increased reproductive performance, decreased the interspawning time, and increased the larvae quality in terms of resistance to stress and higher survival rate.

Source diversity of Artemia enrichment boosts goldfish (Carassius auratus) performance, β-carotene content, pigmentation, immune-physiological and transcriptomic responses

This study aimed to assess the impact of spirulina and/or canthaxanthin-enriched Artemia on the goldfish (Carassius auratus) growth, pigmentation, blood analysis, immunity, intestine and liver histomorphology, and expression of somatolactin (SL) and growth hormone (GH) genes. Artemia was enriched with spirulina and/or canthaxanthin for 24 h. Goldfish (N = 225, 1.10 ± 0.02 g) were tested in five experimental treatments, three replicates each: (T1) fish fed a commercial diet; (T2) fish fed a commercial diet and un-enriched Artemia (UEA); (T3) fish fed a commercial diet and spirulina-enriched Artemia (SEA); (T4) fish fed a commercial diet and canthaxanthin-enriched Artemia (CEA); and (T5) fish fed a commercial diet and spirulina and canthaxanthin-enriched Artemia (SCA) for 90 days. The results showed that the use of spirulina and/or canthaxanthin increased performance, β-carotene content and polyunsaturated fatty acids of Artemia. For goldfish, T5 showed the highest growth performance, β-carotene concentration and the lowest chromatic deformity. T5 also showed improved hematology profile, serum biochemical, and immunological parameters. Histomorphology of the intestine revealed an increase in villi length and goblet cells number in the anterior and middle intestine, with normal liver structure in T5. SL and GH gene expression in the liver and brain differed significantly among treatments with a significant increase in enriched Artemia treatments compared to T1 and T2. In conclusion, the use of spirulina and/or canthaxanthin improved performance of Artemia. Feeding goldfish spirulina and/or canthaxanthin-enriched Artemia improved performance, β-carotene content, pigmentation, health status and immune-physiological response.

Co-Culturing Microalgae with Roseobacter Clade Bacteria as a Strategy for Vibrionaceae Control in Microalgae-Enriched Artemia.

Bacterial communities associated with fish larvae are highly influenced by the microbiota of live prey used as feed (rotifers or Artemia), generally dominated by bacterial strains with a low degree of specialization and high growth rates, (e.g., Vibrionaceae), which can be detrimental to larvae. Co-cultivation of microalgae used in the enrichment of Artemia (e.g., Phaeodactylum tricornutum, or Chlorella minutissima) with Vibrio-antagonistic probiotics belonging to the Roseobacter clade bacteria (e.g., Phaeobacter spp. or Ruegeria spp.) was studied. The introduction of the probiotics did not affect microalgae growth or significantly modify the composition of bacterial communities associated with both microalgae, as revealed by DGGE analysis. The inoculation of P. tricornutum with Ruegeria ALR6 allowed the maintenance of the probiotic in the scale-up of the microalgae cultures, both in axenic and non-axenic conditions. Using Ruegeria-inoculated P. tricornutum cultures in the enrichment of Artemia reduced the total Vibrionaceae count in Artemia by 2 Log units, therefore preventing the introduction of opportunistic or pathogenic bacteria to fish larvae fed with them.

Live-food enriched with Chlorella vulgaris as a potential supplemental diet to enhance performance and immune response of Tor tambroides larvae (Bleeker 1854)

Tor tambroides is one of the Tor species identified in Southeast Asia with a promising aquaculture potential in Malaysia, fetching market price of up to USD 53 per kilogram. It is a slow grower that takes more than two years to reach marketable body weight (∼800 g) in captivity. This study was designed to establish the C. vulgaris enriched Artemia sp. and Moina sp. in enhancing the growth performance of T. tambroides larvae. The larvae were divided into five treatments, control (C) (commercial feed); unenriched Moina (UM); enriched Moina (EM); unenriched Artemia (UA); enriched Artemia (EA). The concentration of C. vulgaris used during enrichment was 1 × 107 algal cells/mL. On 14 to 29 days after hatching (DAH), the larvae were co-fed with the commercial feeds and each treatment four times daily. The highest body weight gained were observed in the larval group fed with EA (18.56 ± 1.02 mg), followed by UA (15.89 ± 2.08 mg) and were statistically different as compared to the UM (6.89 ± 0.51) and EM (6.11 ± 1.09) and C (3.56 ± 1.20) (p < 0.05). The final total length was also the highest in larvae fed with EA (17.8 ± 0.04 mm), followed by UA (17.2 ± 0.0 mm), EM (16.4 ± 0.02 mm), UM (16.0 ± 0.02 mm) and the lowest in C (15.4 ± 0.02 mm). The larvae fed with EA also displayed a significant increase in specific growth rate (4.66%), followed by UA (4.13%) and were statistically different to UM (2.10%), EM (1.88%) and C (1.14%) (p < 0.05). The relative growth rate of the larvae was the highest in EA (92.27%) and lowest in C (17.68%) (p < 0.05). The survival rate of the larvae was the highest in UM and EM with 89.4%, followed by EA (89.13%), UA (88.51%) and C (84.7%). The EA had high and positive upregulation of growth hormone genes (0.16 ± 0.13), myostatin gene (0.11 ± 0.10), MHCC1a gene (0.48 ± 0.12) and CC3 gene (0.28 ± 0.14) and were statistically different as compared to the control group. The enriched Artemia had enhancing effect on the growth performance and expression of the immune and growth genes of the larvae, potentially due to its nutritional contents and better ingestion by the larvae. The study suggests C. vulgaris enriched Artemia can be used in the hatcheries to improve the growth and survival of T. tambroides larvae, shorten its rearing period and increases its yield.

Artemia with Synbiotics Enrichment Improves Resistance Against Vibrio parahaemolyticus AHPND of Litopenaeus vannamei Larvae

Shrimp, a high-protein food commodity, is one of the world's fastest-growing food-producing sectors. The present research aimed to find out the survival and growth of Litopenaues vannamei Post Larva (PL) and the resistance against VpAHND and stress salinity. 1500 PL were reared to two sets of experiments at the density of 50 PL. L-1. The first set is purposed to determine the PL growth, resistance to Vibrio paramaemolyticus AHPND challenge and stress salinity. The second set is purposed to determine the survival rate. A Completely randomized design (CRD) with five treatments and three replications was conducted. The treatments are Artemia enrichment with different Alginate doses and probiotics (400, 600, 800 ppm Alg+pro), probiotics (Pro), and control without any synbiotics addition. PL was reared in 14 days. The survival rate, and weight gain were calculated. At the end of the experiment, 10 PL was challenged against VpAHPND at 1 x 107 CFU mL-1by immersion methods. Twenty PL was exposed to stress salinity and shocked from 25 ppt to 0 ppt. The best survival rate ((78±2%), and tolerance to osmotic stress was reached at PL fed on a combination of alginate and FNCC-002 Lactobacillus bulgaricus probiotics (p&lt;0.05). PL fed on Artemia enriched probiotics reached the highest resistance to severe VpAHNPD. The weight gain among treatments is similar. It can be concluded that synbiotics of alginate as prebiotics and FNCC-004 probiotics work synergically and this might be interrelated with immune response.

Artemia enrichment as modulator of gene expression patterns of Enteroctopus megalocyathus paralarvae at pre-settlement stage

Enteroctopus megalocyathus, the Patagonian red octopus, is the only octopus species for which a complete production cycle in captivity has been accomplished in Chile. The rearing of E. megalocyathus paralarvae from hatching to the settlement of juveniles lasts 90 days and it represents the bottleneck in the culture of this species. The paralarval stages from 1 to 60 days after hatching (DAH) are fed on enriched Artemia while, when pre-settlement behavior appears, from 60 DAH onwards, the feeding protocol is a mixed diet of enriched Artemia and juvenile marine crabs. Marine crustaceans represent a suitable diet to improve E. megalocyathus paralarvae survival, complementing the enriched Artemia to feed the pre-settling paralarvae. To determine the effect of Artemia enrichment on the response of E. megalocyathus at the pre-settling paralarval stage, paralarvae were fed two mixed diets containing juvenile marine crabs (Petrolisthes spp.) and differing only in Artemia enrichment: enriched (complete diet, CD), or unenriched (limited diet, LD). After 30 days of feeding trial, samples consisting of whole paralarvae were collected for transcriptomic analysis using high-quality total RNA to generate six mRNA libraries (two treatments x three biological replicates). A total of 270 genes were differentially expressed between paralarvae fed LD and those fed CD. When classifying the cellular processes in which the genes of LD and CD paralarvae differed significantly, it was observed that the downregulated/upregulated gene ratio was 2/1 in genes related to membrane organization and neuron differentiation. The genes of paralarvae fed a LD for which upregulation was equal to or >20 times compared with those fed a CD were related with increased rearrangement of tissues, molecular transport, energy production, improvement of sensory organs, cellular processes, transcription, and protein catabolic processes. The downregulated genes in paralarvae fed a LD were involved with reduced DNA repair and mRNA replication and elongation, molecular transport, cellular protein modification, cellular component organization, inflammatory cytokines, and biosynthetic processes. It was concluded that removing enrichment from Artemia, even under co-feeding with marine crustaceans, results in notable changes in the transcription that, while not generating a significant detriment to growth in 30 days of experimentation, could affect subsequent growth phases.

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.

Optimizing Artemia Enrichment: A Low DHA/High EPA Protocol for Enhanced n-3 LC-HUFA Levels to Support Greater Amberjack (Seriola dumerili) Larval Rearing.

Most commercial products available for Artemia sp. enrichment include high levels of docosahexaenoic acid (DHA) to boost its nutritional value, though with limited success. In this regard, the present study evaluated the alternative utilization of eicosapentaenoic acid (20 : 5n-3; EPA) oils to improve the n-3 long-chain highly unsaturated fatty acid content (n-3 LC-HUFA) in enriched Artemia sp. to feed greater amberjack (Seriola dumerili) larvae. Five experimental emulsions containing increasing levels of EPA from 0.8% to 60% of total fatty acids (TFA) and n-3 LC-HUFA (1.3%-70.6% TFA) were formulated. Each diet was fed to greater amberjack larvae (17-35 days posthatch (dph)) in three replicate 200-L tanks. The dietary EPA supplementation significantly improved larval growth during the feeding trial and survival at 35 dph (P < 0.05). In addition, larval fatty acid profiles showed a positive correlation with dietary EPA. Finally, despite the sum of total skeletal anomalies and column anomalies were not significantly affected by dietary EPA, increasing dietary EPA, and n-3 LC-HUFA tended to reduce the incidence of these types of anomalies in greater amberjack larvae at 35 dph. Based on these results, S. dumerili larvae could be successfully grown with low DHA but high EPA-rich oil enrichment products when n-3 LC-HUFA content in Artemia sp. is maintained in sufficient amounts.

Effects of carotenoid supplementation on colour, growth and physiological function of the endemic dwarf chameleon fish (Badis badis).

The global ornamental fish trade is expanding in response to increased demand for indigenous fish on the global market, while exogenous carotenoids can improve colouration. The 60-day trial investigated the effect of carotenoid supplementation, via Artemia, on colouration, growth and immunophysiology of Badis badis (dwarf chameleon fish). Carotenoid was enriched at 40 ppm (T1), 80 ppm (T2) and 120 ppm (T3) and compared with controls, C1 (unenriched) and C2 (oil-enriched). Fish larvae (average weight 0.12 g) were fed enriched-unenriched Artemia in triplicates (5 × 3) in aquarium tanks (15 L). C1 and T2 had better skin colour (lightness and whiteness) in the posterolateral and caudal fins respectively. The value of redness (a*) in the anterolateral region was higher in T2 and T3 (p < 0.05). The anterolateral red index was higher (p < 0.05) in T2 and T3, whereas in the posterolateral and caudal fins, T1 and T2 were higher (p < 0.05). Compared to C1 and C2, the hue angle in carotenoid groups was found to be low (p < 0.05). No significant change in the growth performance was noticed (p > 0.05). Immune scores such as lysozyme and alkaline protease were highest in T3 (p < 0.05), whereas protease activity was highest in T2 (80 ppm). Stress biomarkers, viz., superoxide dismutase, catalase and malondialdehyde were low in groups fed enriched Artemia (p < 0.05). The integrated biomarker response means and star plot area were lower in the enriched groups (T1-T3), while T2 was the lowest. Overall findings reveal that dietary carotenoid improves the colouration and immune status, but fail to promote growth. Furthermore, 80 ppm enrichment dose improves the overall performance. The findings can help fish keepers improve fish colour and health status through carotenoid supplementation.

Co-supply with marine crustacean to enriched Artemia as food for the Patagonian red octopus (Enteroctopus megalocyathus) paralarvae

One of the most sensitive problems in the Patagonian red octopus (Enteroctopus megalocyathus) aquaculture is the high mortality of the paralarvae stage. Paralarvae are active hunters, and the enriched Artemia is the most traditional food for this species until 60 days after hatching (DAH). Then, the pre-settlement behavior appears, and co-feeding with juvenile sea crabs is initiated for another 30 days up to 90 DAH when settlement occurs and the paralarvae stage ends. Therefore, the present study aimed to investigate the effect of marine juvenile crabs on the Patagonian red octopus paralarva's feeding history before the pre-settlement stage. Early paralarvae (1 to 15 DAH) were fed two diets: only enriched Artemia (A) or enriched Artemia plus juvenile crab (AC). At 15 DAH, one-half of each group was exchanged with the opposite treatment during the following 35 days of the experimental period. An experimental design resulted in four combinations of early and late diets, A-A, A-AC, AC-A, and AC-AC. The overall performance and the expression of genes related to fatty acid biosynthesis, antioxidant defense system, and stress response were evaluated in paralarvae at 15 and 50 DAH. Besides, fatty acids and amino acids were compared between the four combinations at 50 DAH. At 15 DAH, the main differences were the highest length and growth rate in paralarvae-fed AC. At 50 DAH, after 35 days fed the four combinations of early-late diets, no differences were detected in SGR. In contrast, those paralarvae of AC-A and AC-AC triplicate their survival upon A-A and A-AC. Paralarvae from the A-A combination resulted in the lowest protein content, highest ash, and the highest expression of FADS5. In comparison, paralarvae from the A-AC combination resulted in the highest 18:3n-3 and PUFA n-6 and the lowest amount of free serine. Precisely the contrary to paralarvae fed AC-AC. Therefore, the relevance of the first feeding until 15 DAH upon further paralarvae development is discussed, and how co-feeding with juvenile crabs improves the overall performance compared to using only enriched Artemia.

Effects of the Alga Aurantiochytrium mangrovei FIKU008-Enriched Artemia on Early Stages of the Green Tiger Shrimp, Penaeus semisulcatus

The first aim of the present study was to determine appropriate artemia enrichment levels by using Aurantiochytrium mangrovei FIKU008 served as DHA enrichment source and secondly to test the effects of enriched-Artemia on growth and survival during the early larval stages(M1-PL7) of Penaeus semisulcatus. In the 1st experiment, four different enrichment levels of AUR (0.0,0.6,0.8 and 1.0g/L) against a control commercial solution (S-presso) were tested for 12/24-hours enrichment while in the 2nd experiment, three levels (0.0, 0.6 and 0.8g/L) of AUR enriched-Artemia were fed to larval stages. At the end of both enrichments, DHA and EPA levels were found to be significantly enhanced by using AUR at 0.6 and 0.8g/L. In the 2nd experiment, fatty acid composition of the PL was significantly affected by AUR and the PL fed with enriched diets showed higher n-3 LC-PUFA accumulation in their tissues. The larvae grown from M1 to PL7 displayed higher survivals and growth in the enriched AUR-groups compared to the control(0.0AUR). In conclusion, this study has demonstrated that the use of AUR as enrichment significantly elevated EPA and DHA levels to 0.6-0.8g/L enrichment periods and the enriched-Artemia at such levels were proven to effectively improve growth and survival of the early larval stages of P. semisulcatus.

Short and Long-Term Effects of Early and Late Weaning on Atlantic Cod, Gadus morhua

Studies have shown negative short-term effects of early weaning (EW) in finfish larvae but information on long-term effects of EW on growth and subsequent economic loss is lacking. We evaluated the short- and long-term effects of EW and late weaning (LW) on Atlantic cod. Cod larvae were fed with enriched rotifers from 2 to 35 days post-hatch (dph) and weaning carried out from 21 to 35 dph (EW) or with enriched rotifers from 2 to 29 dph followed by enriched Artemia nauplii from 25 to 56 dph and weaning carried out from 45 to 56 dph (LW). At 190 dph, 50 fish from each tank were tagged with an electronic tag and were transferred to sea cages at 10 months old. At the end of 30 months post-hatch, the weight of the fish was recorded. Our results showed a significant short-term effect of the weaning method on the growth of Atlantic cod at 65 dph, but no significant difference at 90 and 190 dph. However, fish from LW showed a significantly higher body weight compared to fish from EW at 30 months post-hatch. A cost analysis indicated substantial benefit for commercial cod farming by using LW and we recommend using LW to gain sizable financial benefit.

The effect of dietary docosahexaenoic acid (DHA; 22:6n-3) on photoreceptor abundance, rhodopsin expression and growth in developing gilthead sea bream (Sparus aurata) larvae

This study determined the effect of prey DHA on larval gilthead sea bream (GSB; Sparus aurata) photoreceptor abundance, rhodopsin expression, and growth performance. It was carried out in a twenty-eight 400 l conical tank system that was stocked with 100 viable GSB eggs/l/tank. This allowed the testing of 4 levels of rotifer DHA; 0.99 (Low; L), 1.9 (Intermediate low; I-L), 3.2 (Intermediate high; I-H) and 12.1(High; H) mg DHA/g DW rotifer, which were fed (10 rotifers/ml) to 3-16 DPH larvae. These rotifer diets continued to be offered to 17-34 DPH fish, although these larvae predominantly fed on 4 DHA enriched Artemia nauplii treatments that were offered at a concentration from 0.1 nauplii/ml to 4 nauplii/ml, depending on larval age. This resulted in 4 DHA rotifer-Artemia ranges: 0.99-0.0 (L), 1.9-2.6 (I-L), 3.2-7.2 (I-H), and 12.1-11.77 (H) mg DHA/g DW. The 4 DHA treatments and ranges were tested in replicates of 7 conical tanks per treatment. Increasing rotifer DHA significantly (P&lt;0.0001) improved TL, in an exponential manner, throughout larval rearing. DW in 34 DPH larvae was markedly (P&lt;0.05) enhanced with dietary DHA inclusion in the rotifers and Artemia. There was a significant (P &lt; 0.005) prey DHA dose dependent range effect on the abundance of photoreceptor cells in the retina of 34 DPH larvae. The gene expression of rhodopsin in GSB larvae was significantly (P&lt;0.05) upregulated with dietary DHA dose range and larval age (P&lt;0.0001). This study established a link between dietary DHA level with photoreceptor abundance and rhodopsin expression, which led to improved vision, prey acquisition, and growth in developing GSB larvae.

Effects of n-3 HUFA-enriched Artemia on growth, biochemical response, skeletal morphology and stress resistance of Asian sea bass (Lates calcarifer) larvae reared at high temperature

Improving the growth and health status of marine fish larvae to adapt to climate change, is crucial for commercial hatchery production in tropical regions. This study evaluated the effects of dietary essential fatty acids used for Artemia enrichment on growth, biochemical responses, skeletal morphology, and stress resistance of Asian sea bass larvae, reared at high temperatures of 30 °C and 34 °C. Starting 11 days after hatch, Asian sea bass larvae, were fed Artemia, enriched with a commercial emulsion of n-3 HUFA for 14 days, at four concentrations (0, 100, 300, and 500 ppm), at two rearing temperatures (30 °C and 34 °C). The results showed that enriching Artemia with n-3 HUFA significantly improved the final weight and specific growth rate of the larvae fed n-3 HUFA enrichment at 300 ppm, at 34 °C (P < 0.05). Moreover, n-3 HUFA enriched Artemia significantly increased the essential fatty acids of the larvae in parallel with the dose of enrichment. Fish fed unenriched HUFA Artemia resulted in significantly higher ratio of skeletal deformities and lower survival rate following an air exposure test than the larvae fed the n-3 HUFA enriched diets. Overall, the findings showed that n-3 HUFA-enriched Artemia diets had benefits on body weight, specific growth rate, and stress tolerance in Asian sea bass fed HUFA enriched diets, even at high temperatures.

Dietary effects of intensively reared zoeae of Portunus trituberculatus on survival and growth of paralarvae of the East Asian common octopus Octopus sinensis

Zoea larvae of decapod crustaceans are considered to be the best prey organisms for culturing paralarvae of merobenthic octopuses. Because paralarvae consume many zoeae until settling as juveniles, a reliable method is required to rear a large number of zoeae at a high stocking density while maintaining their nutrition at a level to meet the demands of octopus paralarvae. However, when rearing zoeae, “sinking-death syndrome” (where many zoeae are deposited on the bottom of the rearing tanks) results in high mortality. In Experiment 1, to reduce larval deposition and lower the mortality, an upwelling system was installed and tested for its effectiveness in rearing a high stocking density of Portunus trituberculatus zoeae at low mortality. The effect of different supply densities of Artemia on growth and morphology of zoeae was also investigated to evaluate the nutrient sufficiency of zoeae under intensive rearing conditions. In Experiment 2, Octopus sinensis paralarvae were reared for 15 d, supplied with either early-stage zoeae or late-stage (long-term reared) zoeae, to examine the dietary effect of intensively reared zoeae on paralarval survival and growth. In Experiment 1, the proportion of zoeae sinking to the bottom was significantly reduced by using the upwelling system, and the survival rate of zoeae was higher in tanks with an upwelling system at a high stocking density of zoeae (500 individuals L−1) compared to those without. Larger body size and faster morphogenesis of larvae were obtained at the final (fourth) zoeal stage when zoeae were supplied with Artemia at high density compared with those supplied at low density. Composition of docosahexaenoic acid (DHA) in intensively-reared final-stage zoeae (10 d old) was maintained at a similar level to that in first-stage zoeae (1 d old) by supplying a high density of Artemia enriched with DHA. In Experiment 2, a higher survival rate and heavier body weight of paralarvae were obtained in the group supplied mainly with late-stage zoeae compared to that with early-stage zoeae. Because the supply of zoeae was adjusted to the same dry weight for both groups, it is concluded that supplying large-sized zoeae increases the efficiency of prey capture and nutrient absorption by the paralarvae. These results suggest that a combination of the use of an upwelling system and a high-density supply of enriched Artemia is effective for intensive rearing of zoeae, achieving reduced facility costs and more efficient production of high-quality prey for rearing octopus paralarvae.