Current knowledge on use of essential oils as alternative treatment against fish parasites

This review article focuses on current knowledge about in vitro and in vivo experimentation relating to use of essential oils (EOs) to combat fish parasites. In addition, we discuss the existing methodologies used in studies to determine the antiparasitic activity of EOs, along with their toxicity and major compounds. The methodological approaches used to describe the anthelmintic properties of EOs were demonstrated. The consistency of their activity and thus their potential use for fish ectoparasites (in vitro and in vivo) and endoparasites (in vitro) control was reviewed. There is a clear need to find EOs and active agents of EOs to treatment in vivo against endoparasites of fish. Thus, progress may be achieved through considering the beneficial aspects of EOs when their complementarity and potentiality are exploited. EOs are therefore viable alternative sources of therapeutic products against fish parasites. On the other hand, use of chemotherapeutics has been increasingly questioned, such that constant environmental and consumer concerns regarding them now exist. The synergistic functions of EOs, in comparison with the action of one or two major compounds of these oils, seems unquestionable. It is possible that their activity is modulated by several molecules of the major compounds. Lastly, EOs are bioactive products that are viable sources of therapy against fish parasites. Although more than 3000 EOs are known, less than 0.4% of them have been tested on fish parasites. Thus, it has become clear that more studies testing these therapeutic alternatives are required, in order to evaluate the antiparasitic potential of other EOs for controlling fish parasites and to maximize their benefits to hosts

PRIMEIRO REGISTRO DE PREDAÇÃO DE Pterophyllum scalare (OSTEICHTHYES: CICHLIDAE) POR Acestrorhynchus falcirostris (OSTEICHTHYES: ACESTRORHYNCHIDAE)

Piscivorous fish are chain top predators in freshwater ecosystems. Thus, predation of forage fish by top fish in the food web is an expected but not always recorded event. This study reports for the first time the predation on Pterophyllum scalare by   Acestrorhynchus falcirostris.Keywords: Amazon basin; fish; foraging; predation.Peixes piscivorus são predadores de topo de cadeia em ecossistemas de água doce. Assim, a predação de peixes forrageiros por peixes do topo na cadeia alimentar é um evento esperado, mas nem sempre registrado. Este estudo relata pela primeira vez a predação de Pterophyllum scalare por Acestrorhynchus falcirostris.Palavras-chave: Bacia amazônica, peixes, forrageamento, predação

Component communities and annual and seasonal variations of metazoan parasites in Eleotris pisonis (Gmelin, 1789) (Gobiiformes: Eleotridae) in the Amazon River, Brazil

Abstract Our hypothesis for this study was that annual and seasonal variations do not influence the structure of the component communities and the diversity of metazoan parasites of spinycheek sleeper (Eleotris pisonis) in the Amazon River, state of Amapá, Brazil. A total of 164 fish were collected between 2020 and 2021, from which 888 parasites were found. In 2020, five species of parasites were found (one Nematoda, one Digenea, one Acanthocephala, one Arachnida and one Crustacea); and in 2021, five species were also found (three Nematoda, one Digenea and one Crustacea). Larvae of Contracaecum sp. were the dominant taxon throughout the study. The parasite species richness and Brillouin diversity index were higher in 2021, without significant differences between seasonal periods. Some component communities of parasites showed differences between years and between seasonal periods. These facts do not support the hypothesis that such variables would not influence the component communities of the parasites. Lastly, this report provides the first records of Spirocamallanus inopinatus, Genarchella genarchella, Acari, Ergasilus sp., Neoechinorhynchus sp., larvae of Pseudoproleptus sp. and larvae of Contracaecum sp. in E. pisonis

PARÂMETROS BIOQUÍMICOS DE Piaractus mesopotamicus E Colossoma macropomum (CHARACIDAE) E HÍBRIDO TAMBACU (P. mesopotamicus x C. macropomum)

Estudaram-se os valores de glicose plasmática, proteína total sérica e íons séricos (cálcio, potássio, magnésio, sódio e cloreto) em jovens de Colossomoma macropomum Cuvier 1818, Piaractus mesopotamicus Holmberg 1887 e híbrido tambacu (P. mesopotamicus x C. macropomum), mantidos em cultivo intensivo. As concentrações plasmáticas de glicose no híbrido tambacu foram maiores que em P. mesopotamicus e C. macropomum. Os níveis de proteínas totais em P. mesopotamicus foram maiores em C. macropomum e híbrido tambacu. O C. macropomum apresentou maior concentração de sódio e cloreto, ao passo que o P. mesopotamicus mostrou maior concentração de potássio e magnésio. Porém, os níveis de cálcio mostraram-se similares nas três espécies estudadas. O híbrido tambacu apresentou os menores níveis de proteínas totais e níveis intermediários de potássio, sódio, magnésio e cloreto quando comparado ao P. mesopotamicus e C. macropomum. Foram estabelecidos valores basais para peixes sadios criados em cativeiro, os quais poderão ser usados em estudos de comparação futura em populações selvagens de P. mesopotamicus e C. macropomum. PALAVRAS-CHAVES: Bioquímica, Colossoma macropomum, peixes de água doce, Piaractus mesopotamicus, sangue

INFLUENCE OF SEASONALITY IN INFESTATION OF Ergasilus turucuyus (COPEPODA: ERGASILIDAE) IN Acestrorhynchus falcirostris AND Hemiodus unimaculatus (OSTEICHTHYES: CHARACIFORMES) FROM THE RESERVOIR COARACY NUNES, AMAPÁ STATE, BRAZIL

O presente estudo investigou a influência da sazonalidade na infestação de Ergasilus turucuyus nas espécies de peixe Acestrorhynchus falcirostris e Hemiodus unimaculatus do Reservatório Coaracy Nunes, estado do Amapá, Norte do Brasil. Foram coletados 118 espécimes de hospedeiros, sendo 62 A. falcirostris e 56 H. unimaculatus nos períodos de estiagem (outubro de 2012 a fevereiro de 2013) e chuvoso (abril a agosto de 2013) As características físicas e químicas da água  foram similares no período chuvoso e deestiagem. Apesar das diferenças nos níveis de precipitação pluviométrica entre períodos sazonais, os níveis de infestação por E. turucuyus foram similares durante a estação chuvosa e estiagem. Não houve infestação por ergasilídeos em H. unimaculatusno período chuvoso. A infestação branquial por E. turucuyus não influenciou o fator de condição de ambos os hospedeiros, independente do período sazonal. Este foi o primeiro estudo sobre sazonalidade de infestação por E. turucuyus.Palavras-chave: Amazônia, Ectoparasitos, Infestação, Peixes de água doce.The present study investigated the seasonality in infestation of Ergasilus turucuyus in fish species Acestrorhynchus falcirostris and Hemiodus unimaculatus of the Reservoir Coaracy Nunes, Amapa state, Northern Brazil. Were collected 118 specimens of hosts, being 62 of A. falcirostris and 56 of H. unimaculatus during the drainage season (October 2012 to February 2013) and flood season (April-August 2013). The water physical-chemical characteristics were similar during the drainage and flood season. Despite the differences in pluviometric precipitation levels between seasonal, the levels of infestation by E. turucuyus were similar during the drainage and flood season. No infestation by ergasilid was found in H. unimaculatus in the drainage season. The gill infestation by E. turucuyus not influences the condition factor of the both hosts during the drainage and flood season. This was the first study on seasonal infestationby E. turucuyus.Keywords: Amazon; Ectoparasites; Infestation; Freshwater fish

Hematological parameters for the Brycon orbignyanus Valenciennes, 1850 (Osteichthyes: Characidae) intensively bred

This paper determined red blood cell number, total thrombocyte count, and total leukocyte, and differential counts for young Brycon orbignyanus Valenciennes 1849 (Characidae) maintained in fish farming ponds. Mean values and range obtained were as follows: red blood cell count 3.283 (2.110-4.235) x 106 /µl, hemoglobin 10.7 (8.4- 13.1) g/dl, hematocrit 40.2 (35.0-47.0) %, mean corpuscular volume 125.0 (91.5-199.1) fl, mean corpuscular hemoglobin concentration 26.9 (19.5-35.6) g/dl, total thrombocyte count 25,743.0 (11,228.0-54,152.0) µl, total leukocyte count 23,290.0 (9,601.0-37,520.0) µl, lymphocytes 3,642.0 (709.0-9,005.0) µl, neutrophils and heterophils 18,178.0 (7,488.0-29,783.0) µl and monocytes 1,471.0 (147.0-4,976.0) µl. These results found should be useful for evaluation of health status of this fish, when in intensive breeding or other cultivation forms, in addition to serving for comparison of this species in a natural environment

New hosts and distribution records of Braga patagonica, a parasite cymothoidae of fishes from the Amazon

Specimens of Braga patagonica Schiödte  &  Meinert,  1884  (Isopoda: Cymothoidae) from freshwater fishes deposited in Ichthyological Collection of Amazon National Research Institute (INPA), in central Amazon and from fishes from eastern Amazon (Brazil) were investigated. Prevalence, infection intensity and body measures of B. patagonicafor different populations of this cymothoid in wild fishes species from Amazon were carried out. Four species of Serrasalmidae, one Characidae, one Cichlidae, one Cynodontidae, one Curimatidae, one Acestrorhynchidae and one Sciaenidae were recorded as new hosts for B. patagonicain the Amazon. This study indicates a low intensity and low parasitic specificity of B. patagonica, and also recorded the first parasitism by this ectoparasite in farmed Colossoma macropomum, describing its highly pathogenic effect

IMPACT OF THE INVASION FROM NILE TILAPIA ON NATIVES CICHLIDAE SPECIES IN TRIBUTARY OF AMAZONAS RIVER, BRAZIL

Este estudo providenciou a primeira investigação sobre impacto causado pela invasão da Oreochromis niloticus sobre a população de Cichlidae nativos da bacia hidrográfica Igarapé Fortaleza, um tributário do Rio Amazonas no estado do Amapá, no Norte do Brasil. Como uma consequência de escapes e/ou liberações intencionais de O. niloticus de pisciculturas, houve a invasão e estabelecimento dessa espécie de peixe exótico no ecossistema natural, especialmente em área de refugio, alimentação e reprodução das espécies de ciclídeos nativos.  Os fatores que contribuíram para essa invasão e estabelecimento foram aqui discutidos. A invasão de O. niloticus está causando pressão sobre as populações de ciclídeos nativos, os quais encontram-se em baixa densidade populacional, pois 72,7% da biomassa dos ciclídeos (nativos e não nativos) está constituída por O. niloticus. Consequentemente, a CPUE (2,489 kg.h-1) para essa tilápia invasora é muito superior aos valores da CPUE (0,641 kg.h-1) de todas as 16 espécies de ciclídeos nativos juntas. Os resultados indicam uma necessidade de plano de manejo para controle desse peixe invasor, evitando assim a extinção de espécies de ciclídeos nativos. Além disso, serão úteis também para a tomada de decisão crítica de instituições governamentais (estadual e federal) quanto à aprovação da introdução de peixes não nativos na Amazônia ou qualquer outra região do país.Palavras-Chaves: Amazônia, Peixe exótico, Oreochromis niloticus, Crescimento.This study investigated for the first time impact caused by the invasion of Oreochromis niloticus on populations of native Cichlidae species from Igarapé Fortaleza hydrographic basin, a tributary of the Amazonas River in Amapá State, Northern Brazil. As a consequence of escapes and/or intentional releases of O. niloticus from fish farms, there have been the invasion and successful establishment of this exotic fish species in this natural ecosystem, especially in areas of refuge, feeding and reproduction of the native cichlids species. The factors that contributed for this invasion and establishment are discussed here. The invasion of O. niloticus is pressuring the populations of native cichlids which are in a low populational density, as 72.7% of the biomass of cichlids (native and nonnative) is composed of O. niloticus.  Consequently, the value of CPUE (2.489 kg.h-1) for this invasive tilapia is much higher than the value of CPUE (0.641 kg.h-1) for all the 16 species of native cichlids together. The results indicate the need for a management plan designed to control this invasive tilapia and thus avoid the extinction of native species of cichlids. Furthermore, results may also be useful for critical decision making of Brazilian governmental institutions regarding the approval of the introduction of any nonnative fish species in any other region from the country.Keywords: Amazonia; Exotic fish; Oreochromis niloticus; Growth

PRIMER REGISTRO DE METACERCARIAS (DIGENEA) INFECTANDO ASTRONOTUS OCELLATUS (PERCIFORMES: CICHLIDAE) DE LA REGIÓN AMAZÓNICA, BRASIL

This study aimed to report infection by metacercariae ofthe genera Posthodiplostomum Dubois, 1936 (Diplostomidae) and Herpetodiplostomum Dubois, 1936 (Proterodiplostomidae) in the gills of Oscar Astronotus ocellatus Agassiz, 1831 (Cichlidae) from Lake Pracuúba, in the municipality of Pracuúba, State of Amapá (eastern Amazonia), Brazil. Out of 202 A. ocellatus examined, 142 had gills infected by metacercariae of Herpetodiplostomum sp. (prevalence= 70.3%) and Posthodiplostomum sp. (prevalence= 59.4%). However, 97 hosts were infected by both metacercariae species (prevalence= 48.0%). A total of 1123 specimens of Herpetodiplostomum sp. and 463 specimens of Posthodiplostomum sp. were collected and the mean intensity of infection was 7.8 ± 11.6 and 3.9 ± 4.4, respectively. This is the first report of Digenea in A. ocellatus.Este estudio tiene como objetivo el registro de la infestación por metacercarias de los géneros Posthodiplostomum Dubois, 1936 (Diplostomidae) y Dubois Herpetodiplostomum, 1936 (Proterodiplostomidae) en las branquias del Astronotus ocellatus Agassiz, 1831 (Cichlidae) del lago Pracuúba, en el Municipio de Pracuúba, Estado de Amapá, Brasil. De doscientos ejemplares de A. ocellatus examinados, 142 tenian las branquias infestadas por Herpetodiplostomum sp. (prevalencia = 70,3%) y por Posthodiplostomum sp. (prevalencia = 59,4%). Sin embargo 97 hospederos fueron infestados por estas dos especies de metacercarias (prevalencia = 48,0%). Del total de ejemplares de A. ocellatus examinados fueron extraidos 1.123 parasitos de Herpetodiplostomum sp. y 463 parasitos de Posthodiplostomum sp., y la media de intensidad de la infestación fue de 7,8 ± 3,9 y 11,6 ± 4,4, respectivamente. Este es el primer registro de Digenea en A. ocellatus

Effect of increase in temperature on the survival and growth of Macrobrachium amazonicum (Palaemonidae) in the Amazon

Macrobrachium amazonicum is a shrimp species distributed in freshwater habitats of Neotropical regions and is of great importance for the Amazonian economy. This study evaluated the effects of temperature increase on the survival and growth of M. amazonicum. For this, we distributed 360 M. amazonicum juveniles in 70 L tanks, and carried out a 90-day experiment with three treatments (T0: 28 ± 0.5 °C, or room temperature; T1: 30 ± 0.2 °C; T2: 32 ± 0.2 °C), using 4 replicate tanks each with 30 individual shrimp. Culture-tanks were connected to a recirculation system with biofiltration and constant aeration. Animals were fed twice a day using shrimp pelleted commercial food. After 90 days of trial, the total length and body mass gain of the animals cultured at room temperature was 78% and 433%, respectively. The specific growth rate, condition factor, weight gain, and length and survival of animals cultured at 30 and 32 °C were lower than those cultivated at 28 °C, and feed conversion was higher. Therefore, water temperature of 30 and 32 °C may compromise growth and survival of M. amazonicum during cultivation, none of the extreme temperatures may be recommended in practice