Non-native fish (NNF) can threaten megadiverse aquatic ecosystems throughout the planet, but limited information is available for the Amazon Region. In this study we review NNF data in the Amazonian macroregion using spatiotemporal records on the occurrence and the richness of NNF from a collaborative network of 35 regional experts, establishing the Amazon NNF database (ANNF). The NNF species richness was analyzed by river basin and by country, as well as the policies for each geopolitical division for the Amazon. The analysis included six countries (Brazil, Peru, Bolivia, Ecuador, Venezuela, and Colombia), together comprising more than 80% of the Amazon Region. A total of 1314 NNF occurrence records were gathered. The first record of NNF in this region was in 1939 and there has been a marked increase in the last 20 years (2000–2020), during which 75% of the records were observed. The highest number of localities with NNF occurrence records was observed for Colombia, followed by Brazil and Bolivia. The NNF records include 9 orders, 17 families and 41 species. Most of the NNF species are also used in aquaculture (12 species) and in the aquarium trade (12 species). The most frequent NNF detected were Arapaima gigas, Poecilia reticulata and Oreochromis niloticus. The current data highlight that there are few documented cases on NNF in the Amazon, their negative impacts and management strategies adopted. The occurrence of NNF in the Amazon Region represents a threat to native biodiversity that has been increasing “silently” due to the difficulties of large-scale sampling and low number of NNF species reported when compared to other South American regions. The adoption of effective management measures by decision-makers is urgently needed and their enforcement needed to change this alarming trend and help protect the Amazon’s native fish diversity.

This research reports the LWR of ornamental fish from floodplain lakes of the Solimões River basin. The fish were caught in the Paciência island (a fluvial island) in two lakes Sacambú and Cacau using purse seine 7 m × 4 m and mesh size = 3 mm, once during the flood in June 2017 and dry in January 2018. The specimens captured were anesthetized using eugenol 15 mg · L–1, fixed formalin 10% and stored ethanol 70% after 10 days. This study provides the LWR parameters for the species Anablepsoides micropus, Anchoviella jamesi, Cichlasoma amazonarum, Heros efasciatus, Ctenobrycon hauxwellianus, Copella nattereri and Hemigrammus levis. The parameter a ranged from 0.0092 to 0.0229, b ranged from 2.78 to 3.50 and the R2 ranged from 0.985 to 0.998. The results represent new information about ornamental fish from floodplain lakes, with new LWR for five species that are not present in FishBase data set and probably are new for science. This study is preliminary and much work needs to be done especially in the Solimões River floodplain areas and with our research we hope to encourage new studies in the region.

The ichthyofauna of the headwaters of the main tributaries of the mighty Solimões/Amazonas River  has been little studied. Considering the importance of those environments for the overall fish  diversity in that river system, we surveyed the composition of the fish fauna of the upper portion  of Purus River and two of its tributaries (Caeté and Macapá rivers), state of Acre, Brazil. The collections were done in November 2004, using a seine net and a set of gillnets of different mesh  sizes. A total of 735 specimens belonging to 86 species and 28 families were collected. Eight  species, Creagrutus occidaneus, Phenacogaster pectinatus, Prionobrama filigera, Moenkhausia cf.  lepidura, Leptagoniates pi (Characidade), Henonemus punctatus (Trichomycteridae), Toracocharax  stellatus (Gateropelecidae), and Eigenmannia macrops (Sternopygidae) composed nearly half of the  specimens collected. This survey adds 48 new records to the ichthyofauna of Purus River and  elevates to 243 the number of known fish species in that river, but a greater sampling effort is necessary to produce a reasonably complete picture of the fish diversity in the basin.

Esse estudo teve como objetivo descrever a biologia reprodutiva e os hábitos alimentares de Hemigrammus bleheri do médio Rio Negro, estado do Amazonas-Brasil, ao longo de um ciclo hidrológico. Para tanto, analisou-se os estádios de maturação gonadal, tamanho de primeira maturação sexual (L50), fecundidade e período reprodutivo de 260 indivíduos, além da análise do conteúdo estomacal e cálculo do índice de repleção estomacal de 177 indivíduos. Os resultados obtidos demonstram que a espécie possui desova parcelada, com oócitos variando entre 0,06 a 0,66 mm de diâmetro, e fecundidade entre 101-721 oócitos. O L50 foi estimado em 2,8 cm para fêmeas e 2,6 cm para machos. As fêmeas amadurecem com a subida do rio (Dezembro a Maio) e às desovas ocorrem em maior proporção no final da enchente (Março a Maio). A espécie é onívora, consumindo grande parte dos alimentos de origem autóctone. A dieta básica mostrou variações sazonais em sua composição, pois, observou-se que microcrustáceos são frequentes nos períodos de enchente/cheia, e algas filamentosas, quironomídeos e fragmentos vegetais são mais frequentes na vazante/seca. Alterações sazonais na atividade alimentar foram registradas provavelmente influenciadas pelo pulso de inundação. O grau de repleção estomacal foi maior na enchente/cheia e menores na vazante/seca. Palavras-Chave: rodóstomo; alimentação; reprodução; ambiente natural; rio Negro; Bacia Amazônica. REPRODUCTIVE BIOLOGY AND FEEDING HABITS OF Hemigrammus bleheri (CHARACIFORMES: CHARACIDAE) AN ORNAMENTAL FISH THE MIDDLE NEGRO RIVER BASIN, AMAZONAS STATE, BRAZIL ABSTRACTThe aim of this study is to describe the reproductive biology, diet and the feeding activity of Hemigrammus bleheri from middle Rio Negro, State of Amazonas-Brazil, along the a hydrological cycle. For this, the gonadal maturation stage, size of first sexual maturation (L50), fecundity and reproductive period of 260 individuals were analyzed, as well, the stomach contents of 177 individuals were analyzed and their stomach fullness index was calculated. The results indicate that this species has multiple spawning, with oocytes varying between 0.06 and 0.66 mm in diameter, and fecundity between 101-721 oocytes. The first sexual maturation size (L50) was estimated at 2.8 cm for females and 2.6 cm for males. Females mature with the flood pulse (December to May) and spawning occur in greater proportion at the end of the flood (March to May). The species is omnivorous, consuming a large part of the food of autochthonous origin. The basic diet showed seasonal variations in its composition, because it was observed that microcrustaceans have their increased importance in flooding/flood periods, and filamentous algae, chironomids and vegetal fragments are more frequent in the drying/dry season. In addition, seasonal changes in food activity were also recorded, probably influenced by the flood pulse, as the degree of stomach repletion was higher in flooding/flood and lower in drying/dry.

The present study analyzed landing events of commercial fishing of two species of large catfish in 11 fish landing sites along the Madeira River, and temporally and spatially characterized the exploitation of these species before and after the closure of the Jirau and Santo Antônio hydroelectric dams. Our results show that the Madeira River dams have negatively affected the fishing production of Pinirampus pirinampu and Brachyplatystoma platynemum catfish, drastically reducing these species' harvest as well as the incomes of regional fishers. If the irreversible loss of these species of Amazonian catfish is to be avoided, public policies and measures for the management and sustainable handling of this fishery resource must be implemented urgently.

No abstract

The objective of this study was to investigate the parasites occurrences and to determine the rates of infestation/parasitic infection in juvenile Arapaima gigas from seven fish farms in the state of Amazonas, relating to the characteristics of these fish farms. Of the 70 A. gigas evaluated, 43 were infested/infected, with a total of 133 parasites collected. Three fish farms (2, 4, 6) showed the highest levels of prevalence of parasites (100%, 70%, 70%), mean intensity (4.1±2.6, 8.1±9.2, and 2.1±1.3), and mean abundance (4.1±2.6, 5.7±8.1, and 1.5±1.5), respectively. Prevalence ranged from 30% to 100%, mean intensity from 1.0 to 8.1 and mean abundance from 0.3 to 5.7. Monogenea, Digenea, Nematoda (Hysterothylacium sp. and Spirocamallanus sp.) and Acanthocephala (Neoechinorhynchus sp. and Polyacanthorhynchus sp.) were identified. The parasites Hysterothylacium sp. and Neoechinorhynchus sp. were the most prevalent parasites with 31.43% and 15.71%, respectively. The fish presented negative allometry in growth and constant condition factor. Measures to prevent and control the parasitic diseases diagnosed are discussed as well prophylactic practices that contribute to the biosecurity of the farms.

No abstract