Pirarucu Arapaima Gigas Research Articles

Evidence of enteritis, hepatic steatosis and jaundice in juvenile pirarucu (Arapaima gigas) fed high levels of soybean meal

ABSTRACT This study evaluated the effects of replacing dietary fishmeal with increasing levels of soybean meal (0, 15, 30, 45 and 60% corresponding to 0, 11, 22, 33 and 44% inclusion in the formulated diet) on the intestine and liver histomorphology of juvenile pirarucu Arapaima gigas (233 ± 12 g; mean ± SD) fed for 120 days. At the end of the feeding trial, fish fed diets with higher soybean levels (45 and 60%) presented clinical signs such as appetite loss, cachexia and jaundice. In addition, fish fed on 45% and 60% soybean meal had histomorphological alterations in the middle and posterior portions of the intestinal mucosa (enteritis) and high liver lipid deposition (steatosis). Therefore, 45% or 60% of soybean meal is not recommended; however, a replacement of fishmeal by soybean meal of up to 30% (22% inclusion) can be used in diets to feed juvenile pirarucu for long periods.

Effect of pond fertilization on growth performance of pirarucu (Arapaima gigas) during grow-out phase

Fertilization of aquaculture ponds has been pointed out as an efficient practice to improve fish feed conversion and growth performance. In this way, the present study aimed to assess the effect of pond fertilization on the growth performance, body composition, and water quality of juvenile pirarucu Arapaima gigas reared in earthen ponds (600 m²) during the grow-out phase. Two fertilized and two non-fertilized ponds were stocked with 208 juvenile pirarucus (19.9 ± 3.6 g and 15.0 ± 0.9 cm) and reared for 100 days. All four ponds were limed before the study. Ponds were fertilized before fish were stocked and weekly until the end of the experiment, and fish offered feed until apparent satiation. Pirarucu reared in fertilized ponds presented higher final weight (20%) and biomass (19%), further to lower feed intake and feed conversion rate (1.31) than fish reared in non-fertilized ponds (1.61). Pond fertilization did not affect the fish coefficient of variation, which was reduced over the culture cycle. The body composition of fish reared in fertilized ponds presented higher water content, protein, and energy retention rates and lowered crude fat and energy. Fertilized ponds presented lower transparency levels and higher pH from the 50th day of culture, whereas ammonia concentration was higher in the fertilized ponds in the first 25 days. Therefore, pond fertilization is a recommended practice for pirarucu during the grow-out phase.

Frozen zooplankton is efficient as natural food during pirarucu Arapaima gigas weaning

The commercial production of carnivorous fish depends on the feed training that can be made through the direct transition from natural food to inert food. As using live natural food requires care in production, alternative methods of using live food are necessary, such as freezing. Thus, the aim of this study was to evaluate the use of frozen zooplankton as an initial diet in the feed training of pirarucu Arapaima gigas juveniles. Three hundred and twenty pirarucu juveniles (13.94 ± 4.99 g) were submitted to weaning with two different initial diets (treatments): live zooplankton and frozen zooplankton. The co-feeding period was 12 days, with a progressive increase in the amount of feed offered and a decrease in zooplankton every three days. At the end of the training, all fish were ready to be fed with commercial feed. There was no mortality in the experiment and no significant differences (p > 0.05) for weight, length, weight variation coefficient, specific growth rate, intestinal coefficient, hepatosomatic index, muscle layer thickness and height of the branched folds intestinal mucosa, moisture, crude protein and carcass energy for fish that received live or frozen zooplankton as a starter. Isotopic values of δ15 N and δ13C in the fish's muscle were similar (p > 0.05), reinforcing no feeding preference of the fish between the live or frozen zooplankton. The water quality was not influenced by the use of initial diet (p > 0.05). The frozen zooplankton can be used as initial food for pirarucu juveniles feed training, without impairing fish growth and survival.

Experimental co‐infection by Aeromonas hydrophila and Aeromonas jandaei in pirarucu Arapaima gigas (Pisces: Arapaimidae)

In fish, bacteriosis has been widely linked with Aeromonas species, but co-infection by these bacteria has been little addressed. The aims of this study were to report on an outbreak of disease in pirarucu Arapaima gigas caused by Aeromonas and to investigate experimental co-infection and characterize resistance profile, virulence factors and phenotypic and molecular differentiation. Fish samples with clinical signs of bacteriosis were collected and used to study experimental co-infection. The bacterial isolates were characterized phenotypically as Aeromonas hydrophila and Aeromonas jandaei. Virulence genes aerA, gcat, lip, dnase and hlyA were detected using the polymerase chain reaction, while the alt, act and ser genes were not found. Resistance to imipenem and ceftriaxone was observed; however, all isolates were susceptible to most of the antibiotics assayed. Phenotypic tests to determine the presence of metallo-β-lactamases showed positivity only for A. jandaei strains. Assays for the resistance genes kpc, ndm, imp, oxa-48 and vim showed negative results. The co-infection and pathogenicity of A. hydrophila in association with A. jandaei in A. gigas, established in accordance with Koch's postulate, provided experimental support for the existence of synergism between these bacteria. This has several implications relating to occurrences of this co-infection and determinants of virulence.

Detecção de Pseudomonas sp. em pirarucu (Arapaima gigas): um relato de caso na Amazônia Ocidental

Pirarucu (Arapaima gigas)is one of the most important fish in Amazonian fish farming. However, information about its nutritional, zootechnical and microbiological aspects is still scarce. This is especially true for the juvenile phase due to high mortality rates caused by malnutrition, difficulties in food training, endo and ectoparasite infestations, which in turn lead to immunosuppression, favoring secondary bacterial infections that may be present due to various environmental factors(e.g., sudden temperature variations, water acidity and pollution of the aquatic environment) and thestatus of fish. The Pseudomonas sp. species studied in this work is part of the aquatic ecosystem and is considered a contaminant or invader because it infects a wide variety of aquatic species, including pirarucu. Given this assumption, the objective of the study was to report a case of Pseudomonas sp.in the viscera and dorsum of a juvenile pirarucuArapaima gigas(SCHINZ, 1822) detected through bacteriological analysis. In the fish production chainin the Western Amazon, pirarucu is one of the most prominent fish species because of its high zootechnical performance in terms of weight gain and commercial value. However, one of the biggest obstacles in its production chain occurs during the juvenile phase, with high mortality rates caused by mainly bacterial infections, leading to economic losses in fish farming. In this study, Pseudomonas sp. was detected in a sample of dorsum and viscera of a pirarucu fish from a fish farm in the municipality of OuroPreto do Oeste, Rondônia, Brazil.

Effect of size grading on the growth of pirarucu Arapaima gigas reared in earthen ponds

Size grading is a common management practice in fish farming to minimize growth variability. Such practice has not been established for pirarucu Arapaima gigas. Therefore, the present study assessed the effect of size grading on the growth of pirarucu. Juvenile pirarucu were divided into three groups: ungraded fish (U: mean initial weight 1.12 kg), small fish (S: mean initial weight 0.81 kg), and large fish (L: mean initial weight 1.36 kg), and reared for 129 days (phase I) and 158 additional days (phase II), consecutively. No significant difference was observed in the final length, specific growth rate, biomass, survival and feed conversion rate between fish groups. Ungraded fish presented a greater decrease in the coefficient of variation for weight in phase I than in phase II. Size sorting resulted in significantly higher growth after 287 days of farming in the L-graded fish (9.49 kg, final weight), followed by the ungraded group (8.80 kg) and S-graded group (8.01 kg). However, the mean weight of pooled S- and L-graded fish was similar to the ungraded fish group in phase I and phase II, indicating that grading did not improve the general performance of pirarucu in captivity.

Apparent digestibility coefficients of selected protein ingredients for pirarucu Arapaima gigas (Teleostei: Osteoglo ssidae)

Apparent digestibility coefficients (ADCs) of nine protein ingredients were determined for pirarucu Arapaima gigas , a Neotropical fish species with great aquaculture potential in the Amazon. ADCs of crude protein, energy and dry matter were determined by feces sedimentation in cylindrical-conical tanks. Experimental diets were composed of 795 g kg -1 of the reference diet, 5 g kg -1 of chromic oxide and 200 g kg -1 of the following test ingredients: fish by-product meal, salmon by-product meal, poultry by-product meal, hydrolyzed feather meal, meat and bone meal, blood meal, soybean meal, corn gluten meal and corn gluten feed. Blood meal, meat and bone meal and corn gluten feed resulted in low ADCs for pirarucu, whereas corn gluten meal, poultry by-product meal and soybean meal were better digested, indicating that these ingredients may be potential protein sources in feed formulations for pirarucu. The other animal protein ingredients presented intermediate ADCs values and, together with blood meal and meat and bone meal, they demonstrate that the nutritional quality of the animal by-products tested could be improved, especially by enhancing the processing methods of this group of ingredients.

Natural food intake by juvenileArapaima gigasduring the grow-out phase in earthen ponds

In carnivorous fish species, zooplankton is one of the main food items in the early life stages and some fish species continue feeding on such food items further along the life stages even in the farming environment. In this study, the intake of natural food items was assessed in juvenile pirarucu Arapaima gigas reared in earthen ponds. Juvenile pirarucu (12.2 ± 4.32 g and 12.1 ± 1.13 cm) were stocked in fertilized earthen ponds (240 m²). For the analysis of the fish stomach content and plankton in the pond water, the fish and pond water were sampled weekly for 75 days and biweekly until the fish reached a mean weight of 750 g. Although artificial feed was used, pirarucu also ingested the natural food available in the pond water. Among the zooplankton, pirarucu demonstrated feeding preference for cladocerans despite the abundance of rotifers and copepods. Cladocerans were present in more than 80% of the stomach contents of fish up to 300 g and in 65%, 45% and 17% of fish of 301–500 g, 501–700 g and 701–900 g respectively. Copepods were present only in fish up to 500 g at low abundance. High ingestion of insects and plant material was observed in the stomach content of fish of all size classes. The results demonstrate that juvenile pirarucu ingest natural food available in the farming pond and suggests that the adoption of pond fertilization practices may have positive effects on fish growth performance.

<b><i>Braga nasuta</i> (Cymothoidae): an ectoparasite of the Giant Amazonian fish <i>Arapaima gigas</i> (Osteoglossidae) fingerlings cultured in the Amazon region in Northern Brazil

Isopods Cymothoidae are organisms that parasitize several fish species, both marine and freshwater, provoking important physiological alterations and secondary infections. The genus Braga was proposed to harbor three species of parasitic isopods in freshwater fish from South America: B. brasiliensis, B. cichlae and B. nasuta . Posteriorly, other four species were included: B. patagonica , B. amapaensis , B. fluviatilis and B. bachmanni . Regarding the geographical distribution of the genus, there are registers in Brazil, Argentina, Suriname and Paraguay. In this study, 3,625 fingerlings of pirarucu Arapaima gigas were examined from a commercial fish farm in the Amazon region, Para State, to observe and identify possible parasites. A total of eleven ectoparasitic isopods were carefully removed from the body surface of the hosts and fixed in alcohol 70%. They were processed and identified as Braga nasuta . Parasitological indexes were prevalence of 0.303%, mean intensity of 1.000±0.000 and mean abundance of 0.003±0.055. This is the first report of B. nasuta in pirarucu fingerlings.

Effect of density on survival, physiological parameters and water quality during pirarucu transportation in open system

The loading density of pirarucu Arapaima gigas transported for 6 hr in open system was assessed on survival, physiological parameters (blood hematocrit, cortisol, lactate and glucose concentrations) and water quality (temperature, pH, ammonia, dissolved oxygen and carbon dioxide). No mortality was observed after fish transportation at 80, 120 and 160 kg/m³, although ammonia and carbon dioxide concentrations increased and dissolved oxygen decreased. Physiological parameters were not affected by loading density but significant differences were observed between sampling periods (immediately before transport, immediately after transport, 24 and 96 hr after transport), except glucose. Hematocrit values increased with time, whereas lactate concentration decreased. No significant differences were observed in blood cortisol levels before and after transport, but concentration increased gradually for 96 hr after transport. According to the results, 9 kg pirarucu may be transported for up to 6 hr at a loading density of 160 kg/m³.

South American fish for continental aquaculture

AbstractThe South American continent is known for its high production and exports in fisheries and aquaculture, but has not reached its full potential in fish farming. The latest data on fish production in Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Uruguay and Venezuela were explored in this review. Aspects of biology, production, market and health of the species most produced in South America are described in detail. These species include the round fish (Colossomaspp.,Piaractusspp. and hybrids) and catfish (Pseudoplatystomaspp. and hybrids), in addition to the promising pirarucuArapaima gigas, yellowtail tetraAstyanax altiparanaeand silver catfishRhamdia quelen. Among the countries mentioned, Chile and Brazil are two of the largest intensive fish producers in the world. Chile relies primarily on marine fish, whereas Brazil is prominent for continental production. Special emphasis is given to the black pacuColossoma macropomumbecause it is a commonly farmed fish in South American countries and offers several desirable productive characteristics (domesticated, omnivorous and easy to reproduce). Furthermore, this fish has the greatest potential to compete economically with tilapia production in South America. The production of native fish is currently overtaking the production of exotic species in some countries, which is considered a milestone for South American aquaculture. Regarding diseases, the main pathogens are similar to those observed throughout the world, such asIchthyophthirius multifiliis, different species of monogeneans and trichodinids, and the bacteriaAeromonas hydrophila. Local pathogens, such as the parasitesPerulernaea gamitanaeandGoezia spinulosa, are also concerning.

Air‐breathing fishes

Air‐breathing fishes

Chromosomal characterization of the bonytongue Arapaima gigas (Osteoglossiformes: Arapaimidae)

The mitotic chromosomes of the pirarucu Arapaima gigas inhabiting the middle Araguaia River and collected in the municipality of Araguaiana (MT, Brazil) were studied. The chromosomes were analyzed through Giemsa staining, C-banding, Ag-NOR staining and in situ hybridization using an 18S rRNA gene probe. The karyotype had 2n=56 comprising 14 biarmed and 14 uniarmed chromosome pairs in both sexes. No cytologically distinguishable sex chromosome was identified. A single NOR-bearing chromosome pair was detected by Ag-NOR staining and confirmed by 18S rDNA- FISH. Faint constitutive heterochromatin was C-banded in the centromeric region of some chromosomes.

The Origin and Evolution of the Surfactant System in Fish: Insights into the Evolution of Lungs and Swim Bladders

Several times throughout their radiation fish have evolved either lungs or swim bladders as gas-holding structures. Lungs and swim bladders have different ontogenetic origins and can be used either for buoyancy or as an accessory respiratory organ. Therefore, the presence of air-filled bladders or lungs in different groups of fishes is an example of convergent evolution. We propose that air breathing could not occur without the presence of a surfactant system and suggest that this system may have originated in epithelial cells lining the pharynx. Here we present new data on the surfactant system in swim bladders of three teleost fish (the air-breathing pirarucu Arapaima gigas and tarpon Megalops cyprinoides and the non-air-breathing New Zealand snapper Pagrus auratus). We determined the presence of surfactant using biochemical, biophysical, and morphological analyses and determined homology using immunohistochemical analysis of the surfactant proteins (SPs). We relate the presence and structure of the surfactant system to those previously described in the swim bladders of another teleost, the goldfish, and those of the air-breathing organs of the other members of the Osteichthyes, the more primitive air-breathing Actinopterygii and the Sarcopterygii. Snapper and tarpon swim bladders are lined with squamous and cuboidal epithelial cells, respectively, containing membrane-bound lamellar bodies. Phosphatidylcholine dominates the phospholipid (PL) profile of lavage material from all fish analyzed to date. The presence of the characteristic surfactant lipids in pirarucu and tarpon, lamellar bodies in tarpon and snapper, SP-B in tarpon and pirarucu lavage, and SPs (A, B, and D) in swim bladder tissue of the tarpon provide strong evidence that the surfactant system of teleosts is homologous with that of other fish and of tetrapods. This study is the first demonstration of the presence of SP-D in the air-breathing organs of nonmammalian species and SP-B in actinopterygian fishes. The extremely high cholesterol/disaturated PL and cholesterol/PL ratios of surfactant extracted from tarpon and pirarucu bladders and the poor surface activity of tarpon surfactant are characteristics of the surfactant system in other fishes. Despite the paraphyletic phylogeny of the Osteichthyes, their surfactant is uniform in composition and may represent the vertebrate protosurfactant.

A Method to Count Pirarucu Arapaima gigas: Fishers, Assessment, and Management

AbstractThe giant and obligate air‐breathing fish pirarucu Arapaima gigas (also known as arapaima) is a species endemic to the Amazon Basin that is increasingly managed by artisanal fishers because of government failure to control the fishery. In this study the ability of experienced artisanal fishers to count the number of pirarucu at the moment of aerial breathing was assessed. Counts were strongly correlated (r = 0.98) with mark–recapture abundance estimates calculated for the same populations. The potential for trained fishers to train other fishers to count pirarucu without slow and expensive mark–recapture work was also assessed and confirmed. Not only are the counts a cost‐effective method for assessing pirarucu populations, they also allow fisher participation in decision making and contribute to effective management. The increasing number of community‐based management schemes can now be matched with the training of fishers to count pirarucu.

Transport of Pirarucu Arapaima gigas juveniles in plastic bag

This study examined the stress response of pirarucu juveniles in a closed system transport. Pirarucu (Arapaima gigas) is a native Amazonian fish species from the Osteoglossidae family and an obligated air breather. A short duration transport trial (6h) was undertaken comparing closed polyethylene bags filled with atmospheric air (Air group) and bags filled with pure oxygen (Oxi group). Dissolved oxygen was the only water parameter that presented a difference between fish groups, and was saturated in the oxi group as expected. There was no mortality in either group after transport. Fish feeding was observed 36 h after transport for all fish, and normal feeding consumption was observed at 72 h. In both groups physiological responses were similar. Cortisol did not show any significant alteration during the sampled period. Unlike most fish species, cortisol values were unaltered in both groups during sampling, while glucose presented a significant change up to 12 h after transport. The results showed that pirarucu transport in plastic bags could be made with either atmospheric air or pure oxygen, since physiological response to stress, water quality and feeding behavior after 36 h were similar in both groups.

Biomassa sustentável de juvenis de pirarucu em tanques-rede de pequeno volume

O objetivo deste trabalho foi estimar a biomassa sustentável de juvenis de pirarucu Arapaima gigas (Cuvier, 1829) mantidos em tanquesrede de pequeno volume. Durante 200 dias os peixes foram estocados em quatro tanques-rede de 1 m³, cada um com biomassa inicial total de 0,84±0,14 kg (21 peixes/tanque-rede). Os tanquesrede foram colocados em um viveiro de 50 m² com renovação constante de água. Os índices do fator de condição, da conversão alimentar, do crescimento específico e do ganho de biomassa revelaram que a biomassa sustentável de juvenis de pirarucu para a criação intensiva em tanques-rede de 1 m³ foi de aproximadamente 29 kg. O comprimento alcançado pelo peixe, no espaço reduzido do tanque-rede, é um fator limitante para manter bons índices zootécnicos.

Elaboração de uma semi-conserva de pescado de água doce "Picles de Peixe". I. Tempo de cura, acidificação, textura e nível de sal

Neste trabalho são estudadas as condições para a correta combinação entre o tempo de cura, acidificação e nível de sal para produzir uma semi-conserva de pescado de de água doce acondicionada em vidro, utilizando o efeito da combinalção sal/ácido. As espécies utilizadas foram jaraqui (Semaprochilodus spp.), Curimatá (Prochilodus nigricans), Dourado (Brachyplastistoma flavicans) e Pirarucu (Arapaima gigas). Na salmora de cura prelimiar o tempo indicado para se obter uma melhor textura foi de 4 semanas, a acidificação até 4,5 foi alcançada na solução contendo 5% de ácido/100 gramas de pescado e o nível adequado de sal foi de 15% (p/v). Na salmora flavorizante a proporção de ácido foi de 1% (v/v) o que torna o produto de sabor agradável, sal na concentração de 2% (p/v) e a adição de 1% de condimentos.