Feed Regime Slightly Modifies the Bacterial but Not the Fungal Communities in the Intestinal Mucosal Microbiota of Cobia Fish (Rachycentron canadum).

The bacterial community of the intestinal microbiota influences many host functions, and similar effects have been recently reported for the fungal community (mycobiota). Cobia is a tropical fish that has been studied for its potential in marine aquaculture. However, the study of its bacterial community has been underreported and the mycobiota has not been investigated. We analyzed the gut bacterial and fungal profile present in the intestinal mucosa of reared adult cobias fed two diets (frozen fish pieces (FFPs) and formulated feed (FF)) for 4 months by sequencing the 16S rRNA (V3-V4) and internal transcribed spacer-2 (ITS2) regions using Illumina NovaSeq 6000. No significant differences in the alpha diversity of the bacterial community were observed, which was dominated by the phyla Proteobacteria (~96%) and Firmicutes (~1%). Cobia fed FF showed higher abundance of 10 genera, mainly UCG-002 (Family Oscillospiraceae) and Faecalibacterium, compared to cobia fed FFPs, which showed higher abundance of 7 genera, mainly Methylobacterium-Methylorubrum and Cutibacterium. The inferred bacterial functions were related to metabolism, environmental information processing and cellular processes; and no differences were found between diets. In mycobiota, no differences were observed in the diversity and composition of cobia fed the two diets. The mycobiota was dominated by the phyla Ascomycota (~88%) and Basidiomycota (~11%). This is the first study to describe the gut bacterial and fungal communities in cobia reared under captive conditions and fed on different diets and to identify the genus Ascobulus as a new member of the core fish mycobiota.

Selection of Autochthonous Yeasts Isolated from the Intestinal Tracts of Cobia Fish (Rachycentron canadum) with Probiotic Potential.

Some yeast strains have been proposed as probiotics to improve the health of cultured fish. Cobia is a tropical benthopelagic fish species with potential for marine aquaculture; however, one of the main limitations to its large-scale production is the high mortality of fish larvae. In this study, we evaluated the probiotic potential of autochthonous yeasts from the intestines of cobia. Thirty-nine yeast isolates were recovered from the intestinal mucosa of 37 adult healthy cobia by culture methods. Yeasts were identified by sequencing of the ITS and D1/D2 regions of the 28S rRNA gene and typed by RAPD-PCR using the M13 primer. Yeast strains with unique RAPD patterns were characterized in terms of their cell biomass production ability; anti-Vibrio, enzymatic, and hemolytic activity; biofilm production; hydrophobicity; autoaggregation; polyamine production; safety; and protection of cobia larvae against saline stress. Candida haemuloni C27 and Debaryomyces hansenii C10 and C28 were selected as potential probiotics. They did not affect the survival of larvae and showed biomass production >1 g L-1, hydrophobicity >41.47%, hemolytic activity γ, and activity in more than 8 hydrolytic enzymes. The results suggest that the selected yeast strains could be considered as potential probiotic candidates and should be evaluated in cobia larvae.

Microbiome composition and autochthonous probiotics from contrasting probiosis/dysbiosis states in cobia (Rachycentron canadum) fish epitheliocystis.

Microbiome components and bacterial isolates related to healthy and epitheliocystis states in aquaculture cycles of cobia fish were studied. We detected well-defined 16S rRNA amplicon gene sequence variants showing differential abundance in healthy or diseased cycles. Isolation trials were performed, and experimental tests were used to determine probiotic potential of the bacterial strains obtained from water, tissues or live food used in this aquaculture model. The taxonomic affiliation of these strains was cross-compared against microbiome components, finding that some of them had close or identical affiliation to the abundant types found in healthy cycles. Strains belonging to the groups already identified as predominant by culture-independent means were screened as potential probiotics based on desirable activities such as antagonism and antibiosis against marine pathogenic bacteria, quorum quenching, bile acid resistance, antibiotic sensitivity and enzymatic activities for improved nutrient digestion. We have also found that in the tracking of microbiome composition across different developmental stages of cobia, healthy cycles exhibited a consistent high relative abundance of a Mesobacillus sp., while in the diseased cycle the emergence of a Vibrio sp. was observed. Our study suggests that epithelocystis in cobia is associated with a displacement of a symbiotic microbiome community linked to the increase frequency of Vibrio species.

Transcriptomic Profiling and Microsatellite Identification in Cobia (Rachycentron canadum), Using High-Throughput RNA Sequencing.

Cobia (Rachycentron canadum) is a marine teleost species with great productive potential worldwide. However, the genomic information currently available for this species in public databases is limited. Such lack of information hinders gene expression assessments that might bring forward novel insights into the physiology, ecology, evolution, and genetics of this potential aquaculture species. In this study, we report the first de novo transcriptome assembly of R. canadum liver, improving the availability of novel gene sequences for this species. Illumina sequencing of liver transcripts generated 1,761,965,794 raw reads, which were filtered into 1,652,319,304 high-quality reads. De novo assembly resulted in 101,789 unigenes and 163,096 isoforms, with an average length of 950.61 and 1,617.34 nt, respectively. Moreover, we found that 126,013 of these transcripts bear potentially coding sequences, and 125,993 of these elements (77.3%) correspond to functionally annotated genes found in six different databases. We also identified 701 putative ncRNA and 35,414 putative lncRNA. Interestingly, homologues for 410 of these putative lncRNAs have already been observed in previous analyses with Danio rerio, Lates calcarifer, Seriola lalandi dorsalis, Seriola dumerili, or Echeneis naucrates. Finally, we identified 7894 microsatellites related to cobia's putative lncRNAs. Thus, the information derived from the transcriptome assembly described herein will likely assist future nutrigenomics and breeding programs involving this important fish farming species.

Viabilidade economica da produção de formas jovens de bijupirá (Rachycentron canadum) / Economic feasibility of cobia juvenile production (Rachycentron canadum)

O bijupirá (Rachycentroncanadum) é um dos mais importantes peixes marinhos cultivados no Brasil. Neste estudo analisou-se a viabilidade econômica da produção de formas jovens desta espécie. Para dimensionar os custos de produção foram considerados o custo operacional efetivo (COE), custo operacional total (COT) e o custo total de produção (CTP). Os índices para a avaliação da rentabilidade foram a Taxa Interna de Retorno(TIR), o Retorno do Capital (RC) e o Valor Presente Líquído (VPL). A análise de investimento foi realizada por meio da elaboração de fluxo de caixa e determinação de indicadores de viabilidade econômica. O fluxo de caixa foi determinado a partir da confecção das planilhas de investimento, despesas e receitas para um horizonte de projeto de dez anos. As análises demonstraram que a diminuição do preço de venda e da taxa de sobrevivência afeta fortemente a viabilidade econômica. O aluguel da área e a mão-de-obra representaram a maior parcela do custo operacional total (COT). A Taxa Interna de Retorno (TIR) variou de negativa a 232% afetada pelas taxas de sobrevivência (de 5 a 20%) e pelos três preços de venda (R$ 1,50; 2,00 e 2,50/unidade) avaliados. Conclui-se que a produção de formas jovens de bijupirá é economicamente viável quando a sobrevivência é superior a 10% e o preço de venda superior a R$ 2,00/unidade, apresentando indicadores de rentabilidade atrativos, comparada a outros empreendimentos aquícolas.(AU)

Cobia (Rachycentroncanadum) is one of the most important marine fish cultured in Brazil. This study analyzes the economic viability of the cobia juvenile production. For evaluate the cost of production, were considered the effective operational cost (EOC), total cost operational (TCO) and the total cost of production (TCP). The indexes for the evaluation of the profitability were the Internal Return Rate (IRR),PayBackPeriod (PP) and Net Present Value (NPV). Investment analyses were realized through cash flow and determination of economic viability indicators. The cash flow was determined through planeloads of investment elaborations, annual inputs and outputs for a period of tenyears. The analysis showed that the decrease of the price of sale and survivor rate has a hard impact in economic viability. The land rental and labor represents the largest portion of the total cost of production (TCP). The Internal Return Rate (IRR) it varied from negative to 232% affected for the survival rates (from 5 to 20%) and for the three market prices (R$ 1.50; 2.00 and R$ 2.50/unit). It can be concluded that the cobia juvenile production is presented economically viable, when survival rate is higher at 10% and market price is higher at R$ 2.00/unit, with attractive profitabilityindicators compared to other aquaculture ventures.(AU)

Economic feasibility of cobia juvenile production (Rachycentron canadum) / Viabilidade econômica da produção de formas jovens de bijupirá (Rachycentron canadum)

Cobia (Rachycentron canadum) is one of the most important marine fish cultured in Brazil. This study analyzes the economic viability of the cobia juvenile production. For evaluate the cost of production, were considered the effective operational cost (EOC), total cost operational (TCO) and the total cost of production (TCP). The indexes for the evaluation of the profitability were the Internal Return Rate (IRR), Pay Back Period (PP) and Net Present Value (NPV). Investment analyses were realized through cash flow and determination of economic viability indicators. The cash flow was determined through planeloads of investment elaborations, annual inputs and outputs for a period of ten years. The analysis showed that the decrease of the price of sale and survivor rate has a hard impact in economic viability. The land rental and labor represents the largest portion of the total cost of production (TCP). The Internal Return Rate (IRR) it varied from negative to 232% affected for the survival rates (from 5 to 20%) and for the three market prices (R$ 1.50; 2.00 and R$ 2.50/unit). It can be concluded that the cobia juvenile production is presented economically viable, when survival rate is higher at 10% and market price is higher at R$ 2.00/unit, with attractive profitability indicators compared to other aquaculture ventures.

O bijupirá (Rachycentron canadum) é um dos mais importantes peixes marinhos cultivados no Brasil. Neste estudo analisou-se a viabilidade econômica da produção de formas jovens desta espécie. Para dimensionar os custos de produção foram considerados o custo operacional efetivo (COE), custo operacional total (COT) e o custo total de produção (CTP). Os índices para a avaliação da rentabilidade foram a Taxa Interna de Retorno (TIR), o Retorno do Capital (RC) e o Valor Presente Líquído (VPL). A análise de investimento foi realizada por meio da elaboração de fluxo de caixa e determinação de indicadores de viabilidade econômica. O fluxo de caixa foi determinado a partir da confecção das planilhas de investimento, despesas e receitas para um horizonte de projeto de dez anos. As análises demonstraram que a diminuição do preço de venda e da taxa de sobrevivência afeta fortemente a viabilidade econômica. O aluguel da área e a mão-de-obra representaram a maior parcela do custo operacional total (COT). A Taxa Interna de Retorno (TIR) variou de negativa a 232% afetada pelas taxas de sobrevivência (de 5 a 20%) e pelos três preços de venda (R$ 1,50; 2,00 e 2,50/unidade) avaliados. Conclui-se que a produção de formas jovens de bijupirá é economicamente viável quando a sobrevivência é superior a 10% e o preço de venda superior a R$ 2,00/unidade, apresentando indicadores de rentabilidade atrativo

Parâmetros hematológicos e alterações histopatológicas em bijupirá (Rachycentron canadum Linnaeus, 1766) com amyloodiniose / Parameters hematological and histopathologic alterations in cobia (Rachycentron canadum Linnaeus, 1766) com amyloodiniose

O objetivo do trabalho foi descrever os parâmetros hematológicos e as alterações histopatológicas em bijupirás infectados por Amyloodinium ocellatum. Um grupo de 27 peixes foi anestesiado para coleta de amostras de sangue e eutanasiados para coleta de muco e fragmentos de tecido cutâneo e branquial. Foram avaliadas a prevalência e a intensidade parasitária da infecção, assim como os valores de parâmetros hematológicos e alterações histopatológicas. A prevalência parasitária nas brânquias foi de 100% e no muco foi de 80,8% e as intensidades parasitárias médias foram de 683,5 nas brânquias, e 67,1 no muco cutâneo. Os valores médios dos parâmetros hematológicos foram: eritrócitos 4,3x10(6)µL; VG 26%; VGM 64,2fL; proteína plasmática 5,8mg/dL; trombócitos 5,2 x10³/µL e leucócitos 3,6 x10³/µL. Além disso, foram verificadas hiperplasia do epitélio respiratório acompanhada de fusão lamelar, descolamento do epitélio, dilatação do seio venoso, formação de aneurisma, ruptura do epitélio lamelar, hemorragia, necrose, reação inflamatória linfocítica. O parasito foi observado nas lamelas branquiais, o VMA variou do grau discreto ao severo e o IAH foi de 76,8. A pesquisa assume importância por se tratar dos primeiros estudos em Rachycentron canadum, um peixe que se destaca com potencial ao cultivo.(AU)

The aim of this study was to describe the hematological parameters and histopathologic alterations in cobia infected by Amyloodinium ocellatum. A group of 27 fish were anesthetized to collect blood samples and euthanatized to collect mucus and tissue fragments of skin and gills. The prevalence and parasitic intensity of the infection, besides hematologic parameters and histopathologic alterations, was measured. Parasite prevalence in the gills was 100% and in the mucus 80.8%, and the average intensity of infection in gills and skin was 683.5 e 67.1 respectively. The mean values of hematological parameters were: erythrocytes 4.3x10(6)μL; PCV 26%, MCV 64.2 fL, plasma protein 5.8mg/dL, thrombocytes 5.2x10³/μL and leukocytes 3.6x10³/μL . Furthermore was found hyperplasia of the respiratory epithelium accompanied by lamellar fusion, detachment of the epithelium, venous sinus dilatation, aneurysm formation and rupture of the lamellar epithelium, hemorrhage, necrosis and lymphocytic inflammatory reaction. The parasite was observed between the gills lamellae, the AMV ranged from mild to severe and AHI values were 76.8. The study assumes importance because it is the first study in Rachycentron canadum, a fish that stands out with potential for growing.(AU)

Parâmetros hematológicos e alterações histopatológicas em bijupirá (Rachycentron canadum Linnaeus, 1766) com amyloodiniose / Parameters hematological and histopathologic alterations in cobia (Rachycentron canadum Linnaeus, 1766) com amyloodiniose

O objetivo do trabalho foi descrever os parâmetros hematológicos e as alterações histopatológicas em bijupirás infectados por Amyloodinium ocellatum. Um grupo de 27 peixes foi anestesiado para coleta de amostras de sangue e eutanasiados para coleta de muco e fragmentos de tecido cutâneo e branquial. Foram avaliadas a prevalência e a intensidade parasitária da infecção, assim como os valores de parâmetros hematológicos e alterações histopatológicas. A prevalência parasitária nas brânquias foi de 100% e no muco foi de 80,8% e as intensidades parasitárias médias foram de 683,5 nas brânquias, e 67,1 no muco cutâneo. Os valores médios dos parâmetros hematológicos foram: eritrócitos 4,3x10(6)µL; VG 26%; VGM 64,2fL; proteína plasmática 5,8mg/dL; trombócitos 5,2 x10³/µL e leucócitos 3,6 x10³/µL. Além disso, foram verificadas hiperplasia do epitélio respiratório acompanhada de fusão lamelar, descolamento do epitélio, dilatação do seio venoso, formação de aneurisma, ruptura do epitélio lamelar, hemorragia, necrose, reação inflamatória linfocítica. O parasito foi observado nas lamelas branquiais, o VMA variou do grau discreto ao severo e o IAH foi de 76,8. A pesquisa assume importância por se tratar dos primeiros estudos em Rachycentron canadum, um peixe que se destaca com potencial ao cultivo.

The aim of this study was to describe the hematological parameters and histopathologic alterations in cobia infected by Amyloodinium ocellatum. A group of 27 fish were anesthetized to collect blood samples and euthanatized to collect mucus and tissue fragments of skin and gills. The prevalence and parasitic intensity of the infection, besides hematologic parameters and histopathologic alterations, was measured. Parasite prevalence in the gills was 100% and in the mucus 80.8%, and the average intensity of infection in gills and skin was 683.5 e 67.1 respectively. The mean values of hematological parameters were: erythrocytes 4.3x10(6)μL; PCV 26%, MCV 64.2 fL, plasma protein 5.8mg/dL, thrombocytes 5.2x10³/μL and leukocytes 3.6x10³/μL . Furthermore was found hyperplasia of the respiratory epithelium accompanied by lamellar fusion, detachment of the epithelium, venous sinus dilatation, aneurysm formation and rupture of the lamellar epithelium, hemorrhage, necrosis and lymphocytic inflammatory reaction. The parasite was observed between the gills lamellae, the AMV ranged from mild to severe and AHI values were 76.8. The study assumes importance because it is the first study in Rachycentron canadum, a fish that stands out with potential for growing.

Bactérias potencialmente patogênicas isoladas de beijupirá cultivado

As doenças de peixes são um fator limitante no desenvolvimento da aquicultura e as bactérias são economicamente muito significantes. O beijupirá (Rachycentron canadum) possui grande potencial para alavancar a maricultura brasileira, mas pouco se sabe sobre o manejo sanitário de sistemas offshore e sobre as doenças de maior ocorrência durante o cultivo. Objetivou-se isolar e identificar bactérias dos gêneros Vibrio, Aeromonas, Pseudomonas, Streptococos e Flavobacterium de beijupirás cultivados em sistema offshore e avaliar o perfil de resistência dos microrganismos isolados frente a drogas antimicrobianas. Coletou-se fragmentos de cérebro, fígado e rim de 74 animais para isolamento de bactérias pelo método indireto. 30 estirpes de Vibrio e 74 de Aeromonas foram isoladas de cérebro, fígado e rim de 74 beijupirás cultivados em sistema offshore em Pernambuco entre os meses de novembro e dezembro de 2010 e janeiro a julho de 2011. As espécies isoladas foram Vibrio algynolyticus, V. cincinnatiensis, V. fischeri, V. ichthyoenteri, V. mediterranei, V. natriegens, V. natriegens NCMB 1900 e Vibrio spp. e Aeromonas media, A. salmonicida, A. salmonicida spp. salmonicida, A. salmonicida spp. achromogenes, A. schubertii, A. sobria, A. veronii spp. veronii, A. veronii spp. sobria e Aeromonas spp.. Todos os isolados obtidos foram sensíveis a enrofloxacina (5?g), tetraciclina (30?g), cloranfenicol (30?g), florfenicol (30?g) e gentamicina (30?g), exceto o Vibrio spp. que demonstrou múltipla resistência. Em exposição à ampicilina (10?g), apenas o Vibrio fischeri foi sensível. Beijupirás aparentemente saudáveis podem estar infectados com bactérias potencialmente patogênicas a peixes e seres humanos.

New records of parasites for culture Cobia, Rachycentron canadum (Perciformes: Rachycentridae) in Puerto Rico / Nuevos registros de parásitos para cultivo Cobia, Rachycentron canadum (Perciformes: Rachycentridae) en Puerto Rico

Intensive aquaculture sometimes provides conditions favorable for parasites that are not ordinarily found on culture fishes in the wild, and the use of introduced stocks sometimes introduces non-indigenous species to the habitat. When officially asked about the culture of Cobia Rachycentron canadum (Linnaeus) in Puerto Rico, the authors responded that it was unlikely to cause harm. It was assumed that a well-known culture facility in Florida would assure parasite-free stocks. Subsequent examinations of stocked juveniles surprisingly found parasites new to this fish. An outbreak of Slime-blotch disease, Brooklynella hostilis Lom & Nigrilli, 1970 (Dysteriida: Hartmannulidae) occurred in juvenile Cobia after they were shipped from Florida and stocked. This apparently represents a local parasite that took advantage of the weakened and/or crowded fish. The universal aquarium and culture superparasite, Marine Ich, Cryptocaryon irritans Brown, 1951 (Colpodia: Ichthyophthiriidae) was introduced with a shipment of juvenile Cobia from Florida. This may not be serious, since the parasite occurs worldwide, unless it represents a new strain to Puerto Rico. Marine Costia, Ichthyobodo sp. (Kinetoplastida: Bodonidae) was introduced into Puerto Rico with juvenile Cobia shipped from Florida. This parasite has caused some severe problems in aquaculture hatcheries in Hawaii and Texas after it was introduced with cultured organisms. Thus far, it has not caused any problems locally, but Puerto Rico lacks the marine hatchery facilities where such outbreaks would occur. The question of whether it is established locally will have to wait the development of similar facilities in Puerto Rico. These three species of parasites represent new host records for Cobia. The non-indigenous Ichthyobodo sp. represents new locality records for the tropical Atlantic, Caribbean, and Florida and Puerto Rico. Cobia mature more quickly in culture than in the wild and thus female Cobia apparently mature sufficiently before harvest to attract wild male Cobia to the net pen culture facilities. This represents a potential source of parasite and disease infection for the cultured and wild fish. Rev. Biol. Trop. 54 (Suppl. 3): 1-7. Epub 2007 Jan. 15.

En un criadero del pez Rachycentron canadum establecido en Puerto Rico a partir de especímenes de Florida hallamos parásitos nuevos. La enfermedad causada por Brooklynella hostilis Lom and Nigrilli, 1970 (Dysteriida: Hartmannulidae) podría indicar que un parásito local tomó ventaja de los peces debilitados y/o hacinados. También hallamos Cryptocaryon irritans Brown, 1951 (Colpodia: Ichthyophthiriidae), parásito cosmopolita. También llegó de Florida Ichthyobodo sp. (Kinetoplastida: Bodonidae), el cual hasta ahora no ha causado ningún problema localmente, pero es un nuevo registro para el Atlántico tropical, el Caribe, Florida y Puerto Rico. Los tres parásitos son huéspedes nuevos de R. canadum. Aparentemente, antes de la cosecha las hembras maduran lo suficiente para atraer machos salvajes hacia los cultivos. Esto representa una potencial fuente de infección.