Piaractus Brachypomus Research Articles

Albendazole is effective for controlling monogenean parasites of the gills of Piaractus brachypomus (Serrasalmidae) and Megaleporinus macrocephalus (Anostomidae).

Monogenean infestations can cause high mortality in farmed fish and therefore significant economic losses. The present study investigated the efficacy of albendazole in therapeutic baths against monogeneans of Piaractus brachypomus Cuvier, 1818 and Megaleporinus macrocephalus (Garavello & Britski, 1988). For both fish, a 24 hours therapeutic bath with albendazole concentrations of 150, 300 and 500 mg/L were tested against monogeneans from the gills. The baths had an efficacy from 61.4 ± 32.9 (95%CI=64.5) against monogeneans of P. brachypomus, and from 95.4 ± 5.6 (95%CI=10.9) against monogeneans of M. macrocephalus. In P. brachypomus, the hepatosomatic index (HSI) in fish exposed to 150 mg/L of albendazole was higher than in fish exposed to 300 mg/L. The splenosomatic index (SSI) values in fish exposed to 150 mg/L of albendazole were lower than in fish exposed to 300 mg/L. In M. macrocephalus, the HSI and SSI values decreased in treatments with 150, 300 and 500 mg/L of albendazole to control and treat infestations by monogeneans. For M. macrocephalus, 150 mg/L of albendazole can be used to control and treat infestations by monogeneans, while for P. brachypomus 500 mg/L of albendazole can be used in a 24 hours bath.

Taxonomic studies of Piaractus brachypomus (Cuvier, 1818) (Serrasalmidae): a non-native species collected from Polish water bodies and laboratory culture

Taxonomic studies of Piaractus brachypomus (Cuvier, 1818) (Serrasalmidae): a non-native species collected from Polish water bodies and laboratory culture

A Study of Some Biological Aspects of Pacu Piaractus Brachypomus (G. Cuvier, 1818)

The present study attempts to shed light on some biological aspects and characteristics of Piaractus brachypomus, including some biometrics, phenotypic and feeding pattern that characterizes this species. Besides, the study touches upon the body shape and the Otolith. These fish species have recently been seen frozen in the Iraqi local market. The standard length of fish specimens in this study reach 26.55cm it exceeded the specimens of Pacu fish collected from other studies from other countries, As well the specimens weight was 632gm it exceeded other studies mentioned in this manuscript. As the irregularity in the distribution of teeth rows, especially in the lower jaw was clear in our specimens. The average weight of some skull bones of Piaractus brachypomus specimens is 2.25g, which gives evidence of the heaviness of the bones of this species.

Development, characterization and stability of a white cachama pâté-type product (Piaractus brachypomus)

The objective of the work was to formulate, characterize and evaluate the stability of a product based on white cachama (Piaractus brachypomus). From four lipid sources (pork back fat, canola oil, olive oil or sacha inchi oil), the one with the highest acceptance rate was selected based on the acceptance index and sensory characteristics. The formulation was optimized using the response surface method; 15 formulations were used in triplicate, evaluating the pH, moisture, colour and sensory acceptance values. The macronutrient composition and lipid profile of the optimal formulation was determined; its stability was evaluated under refrigeration conditions by measuring lipid and protein degradation, changes in colour, texture, changes at the microbiological and sensory levels. It was found an optimal proportion of inclusion of 50% white cachama pasta, 21% canola oil and 23% water. The stability of the final product obtained was 42 days, with 82% of acceptability index. This product could be an alternative to other pâté-type products from other species.

Effects of water temperature and feeding time on growth performance and physiological parameters of Piaractus brachypomus juveniles

This study evaluated the effects two water temperatures and two feeding times on the growth performance, hematology, and blood biochemistry of Piaractus brachypomus juveniles at an early stage of development. Fish (2.99 ± 0.04 g) were distributed in 12 tanks at a density of 0.2 fish L−1, with the water being maintained at 28 °C in six tanks and decreased to 24 °C at the beginning of the experiment in the other six. The following treatments were tested with a commercial diet for 40 days using a 2 × 2 factorial design with three replicates each: 24MF (24 °C and fed at 8 h30 and 13 h30); 28MF (28 °C and fed at 8 h30 and 13 h30); 24AF (24 °C and fed 11 h00 and 16 h00), and 28AF (28 °C and fed at 11 h00 and 16 h00). Final weight (FW), total length (TL), weight gain (WG), daily weight gain (DWG), specific growth rate (SGR), feed intake (FI), hemoglobin, glucose, triglycerides, and cholesterol were evaluated after 20 days and verified an effect of temperature, with higher values for 28 °C, while no significant differences were found for feed conversion ratio (FCR) and protein efficiency rate (PER). None of the growth performance parameters were influenced by feeding time and there was no significant interaction between temperature and feeding time after 20 days. Feeding time influenced cholesterol after 20 days, with higher values for AF strategies. All growth performance parameters and hemoglobin, glucose and triglycerides showed an effect of water temperature after 40 days, with higher values for 28 °C, while no significant differences were found for FCR and PER. Triglycerides and cholesterol were also influenced by feeding time, with higher values for AF strategies. Hepatosomatic, mesenteric fat and viscero-somatic indexes were not influenced by temperature, feeding time, or their interaction. Juvenile P. brachypomus can regulate and adjust their physiological variables in response to low water temperature, showing good FCR and PER. Furthermore, the feeding times evaluated in the present study had little influence on growth performance and physiological parameters, with both feeding times being recommended for commercial production of the species at an early stage of development (initial weight ~ 3 g).

Management of the First Feeding of Dorada Brycon sinuensis with Two Species of Cladocerans

The management of the first feeding is a critical stage in the viability of the larvae and fingerling rearing. So far, the first feeding of the bryconids record the best results when fed with forage larvae; thus, the aim was to evaluate two species of cladocerans as live prey in the first feeding of dorada Brycon sinuensis and to evaluate their effects on the control of cannibalism. Larvae (1.2 ± 0.15 mg and 5.9 ± 0.4 mm initial weight and total length) were fed Moina minuta (Mm), Macrothrix elegans (Me) or a mixture (50:50) of cladocerans (Mix) at a rate of 20 prey mL−1, once for 24 h. Another dorada larvae group were fed newly hatched larvae of Piaractus brachypomus (4.5 ± 0.9 mm) as forage larvae (FL) in a ratio of 2:1 (prey:predator). The larvae were stocked to 50 L−1 in aquaria with 5 L of useful volume (12 per treatment). The growth, survival, stress resistance, cannibalism mortality, and the number of prey in the gut contents were analyzed. Dorada larvae fed FL showed higher growth, but those fed Mm showed the highest survival rate (76.1 ± 6.6%) and the lowest cannibalism mortality (16.8 ± 3.7%) (p < 0.05). The use of the cladocerans allowed high survival and stress resistance (95.3 ± 2.4%), and M. minuta proved to be a suitable prey for cannibalism control in the management of the first feeding of dorada larvae.

Farming practices and farmers' perspective of a non-native fish red-bellied Pacu, Piaractus brachypomus (Cuvier, 1818) in India

Burgeoning population growth, increasing affluence, and changing dietary habits of people have caused a phenomenal rise in fish demand over the years in India. Diversification of aquaculture species aimed at increasing yield and providing a wider choice of fish protein to the consumers has led to the introduction of several more affordable species into the culture system. Of these, few fish species are yet to get government nod for culture, but these have increasingly been adopted by the farmers. Red-bellied pacu, Piaractus brachypomus is one of such kinds which has increased its spread in culture system to more than 2500 ha ever since its introduction in 2003–2004. The present attempt envisaged a systematic study to find the status of this species in the culture system, especially in the three States, i.e. Andhra Pradesh, Kerala, and West Bengal where its adoption has increased considerably. A total of 351 pacu farms were surveyed using a structured open-ended questionnaire during the period 2011–2015 in these three States. The survey revealed a gradual increase in culture area and production of pacu during the five years. There was a proportionately higher increase in the sale price of pacu compared to other concurrent major cultured species such as the Indian major carps and striped catfish. The majority of the farmers (87%) practicing pacu farming in the three studied states opined in favour of the culture of pacu due to its overall profitability. The findings of this study will be helpful for making informed decisions by the policymakers for the expansion of its culture in the country.

Growth, red blood cells, and gill alterations of red pacu (Piaractus brachypomus) fingerlings by chronic exposure to different total suspended solids in biofloc

AbstractChronic exposure to high biofloc total suspended solids (TSS) could affect growth, red blood cells, and generate gill alterations in fish. Red pacu, Piaractus brachypomus, fry (2.7 ± 0.5 g weight) were exposed to different biofloc TSS concentrations with low (T1: 200–300), and medium (T2: 400–600 mg/L) levels and compared to a treatment control (TC) without solids during a 45‐day period in 50 L experimental units (in quadruplicate). Water quality, productive parameters, red blood cell values, and gill histopathological alteration index (HAI) were assessed. Red pacu reached higher final biomass (11.34 ± 0.73 kg/m3), better growth (DWG = 0.30 ± 0.03 g/day) and food conversion rate (1.05 ± 0.02) in TC than in biofloc treatments (p < .05). T2 had higher RBC count, and lower hemoglobin, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration (p < .05) than T1 and TC. The histological sections of TC gills showed monogenean parasites in low quantity; thus, the HAI value was similar among treatments and corresponded to low to medium gill damage. Growth, red blood cell values, and gill morphology of red pacu fingerlings were affected by moderate (400–600 mg/L) chronic exposure to TSS concentration in biofloc.

Ecosystem vulnerability of floodplain wetlands of the Lower Brahmaputra Valley to climatic and anthropogenic factors

Abstract This study assessed the vulnerability of 16 floodplain wetlands (beels) of the Lower Brahmaputra Valley, Assam, India, in relation to a range of natural and anthropogenic factors including climate change. The total water-spread area of the selected beels varied widely (8–50 ha), with 68.75% of the beels showing a reduction in water-spread area over the past 30 years. High levels of siltation and encroachment and detachment of marginal areas through the construction of roads were the major factors responsible for the reduction in the water-spread area of the beels. The reduction was observed to be in the range of over 33% in three beels (Raghunath Sora, Chulkani, and Dudua beel) to 83% in Bhoishpuri beel. In addition, one beel (Chulkani) experienced reduction in its deep pool area, which is an important wetland area that provides shelter to brood fishes during the dry season. Only 12.5% of the beels studied practiced enclosure (pen) culture for rearing fish. None practiced cage culture. Our study showed that only two beels (Bhoishpuri and Tariachora) were free from exotic fishes; the remaining surveyed beels reported exotic species such as, Cyprinus carpio (Common Carp), Ctenopharyngodon idella (Grass Carp), Hypophthalmichthys molitrix (Silver Carp), H. nobilis (Bighead Carp) and Piaractus brachypomus (Pacu). The prevalence of exotic fishes in the majority of the beels (due both to escape from nearby aquaculture ponds during floods and intentional stocking in certain beels) would have adversely affected the diversity of indigenous fishes in those wetlands. From discussion with the fishers, 50% of the beels surveyed experienced a reduction in the number of fish species from that recorded 10–20 years ago. In addition to climate change-related factors (e.g. abnormal rains, floods, or drought-like situations), other factors – both natural (e.g. hyper-nutrification) and anthropogenic (e.g. construction of roads, houses, and other structures) – also adversely affected the studied wetlands. To help cope with these factors and increase the adaptive capacity of fishers, four measures aimed at mitigation are suggested. These are: the practice of enclosure aquaculture in beels; the construction of floating macrophyte refuges (katal); deep pool refuges; and stock enhancement programmes with climate-resilient indigenous fishes.

Anesthesia with eugenol and menthol for Piaractus brachypomus (Cuvier, 1818): Induction and recovery times, ventilation frequency and hematological and biochemical responses

This work evaluated the use of eugenol and menthol as anesthesia for juvenile Piaractus brachypomus. Experiment I determined the times for anesthesia induction and recovery using different concentrations of eugenol and menthol (0, 25, 50, 75, 100 and 125 mg L−1), as well as their effects on ventilation frequency (VF) for two size classes: Juveniles I - 0.87 ± 0.20 g and Juveniles II - 17.14 ± 3.27 g for eugenol and Juveniles I - 0.83 ± 21 g and Juveniles II - 16.83 ± 2.78 g for menthol. Based on data from Experiment I, Experiment II evaluated the effects of 0, 25 (beyond the recommended times for induction and recovery) and 50 mg L−1 (within the recommended times for induction and recovery) of eugenol and menthol (independent tests) on hematological and biochemical parameters of fish measured at two blood collection times (1 h post-induction and 24 h post-recovery). Sixty juveniles weighing 16.92 ± 3.34 g and 60 juveniles weighing 18.49 ± 3.07 g were used to evaluate eugenol and menthol, respectively. Survival was 100% at 24 h after the end of Experiment I. Eugenol concentrations between 50 and 100 mg L−1 were able to induce deep anesthesia for both juvenile size classes, while menthol was able to induce deep anesthesia at concentrations between 25 and 100 mg L−1 for Juveniles I and between 50 and 125 mg L−1 for Juveniles II. The use of 50 mg L−1 of eugenol was able to reduce VF during recovery and prevent an increase in plasma glucose while having little influence on hematological and biochemical parameters after handling. The use of 50 mg L−1 of menthol also reduced VF during recovery and did not cause changes in blood parameters that would be harmful to fish physiology.

Stakeholder perceptions and strategies for management of non-native freshwater fishes of Andaman and Nicobar Islands, India

Abstract This article examines the non-native fishes in the freshwater bodies of Andaman and Nicobar Islands with a focus on understanding the perception of stakeholders towards providing management solutions. A total of 56 freshwater fish species were reported from Andaman and Nicobar Islands of which 23 species were non-native to the Islands introduced either accidentally or deliberately. Among the 23 fishes introduced, 13 species were found to be transplanted from Indian waters into the Islands and 10 species were non-native to Indian waters. Mosquito Fish (Gambusia affinis), Mozambique Tilapia (Oreochromis mossambicus), Silver Barb (Barbonymus gonionotus), Red Bellied Pacu (Piaractus brachypomus), and Common Carp (Cyprinus carpio) are some of the important invasive species found here. Stakeholder perception studies were undertaken through semi-structured questionnaire and five point likert scale questions. The respondents (N=133) were classified into two groups as a) Fish farmers and b) Research/development personnel. Multinomial logistic regression analysis revealed that the profession of the respondents significantly influenced the awareness about the non-native fishes (p<0.001). Fish farmers (4.04±0.04) and Research/development (4.47±0.21) respondents mutually agreed on the need for awareness and education on the issue of non-native fishes (p<0.01). A management framework is suggested to address the issue of non-native fishes towards effective planning, conservation and management of the fragile Island ecosystems.

Diet of Exotic Pirapitinga Piaractus brachypomus (Cuvier, 1818) From Vembanad-Kole Wetland, India, as Inferred From Gut Content Analysis and DNA Barcoding

Gut contents of the exotic characid fish Piaractus brachypomus (Cuvier, 1818) that escaped into the Vembanad-Kole Wetland, India, during the floods were examined for their gut food spectrum. The qualitative analysis of gut contents showed that the fish is an omnivore with detritus (27 %) as the most dominant food item followed by, plant matter (25 %), crabs (16 %), molluscs (12 %), fish (11 %) and insects (7 %), respectively. DNA barcoding of the gut contents revealed taxa such as Puntius mahecola (Valenciennes, 1844) (Cyprinid fish), Bellamaya sp. (Mollusca, Gastropoda, Viviparidae), Spiralothelphusa sp. (Crustacea, Brachyura, Gecarcinucidae) and Ictinogomphus sp. (Insecta, Odonata, Gomphidae) among diet contents. Ontogenic diet shift was not recorded, and none of the fishes showed empty guts, indicating the higher feeding rate and abundance of food in the habitat. The most predominant food item of P. brachypomus in the Vembanad-Kol wetland system is crabs in terms of percentage occurrence, percentage number, percentage volume, index of preponderance, and index of relative importance. Piaractus brachypomus showed greater variations in diet spectrum from their frugivorous nature in the home range (Amazon basin) to a more generalist heterogeneous feeding nature in the introduced ecosystem. The study found that in a highly biodiverse ecosystem, the introduced alien fish may compete with native fish and feed on native organisms. The paper suggests a precautionary approach in flood plain aquaculture, especially with the increase in extreme climatic events and holistic studies on invasion biology to manage invasive species.

Outbreak of hirudiniasis in aquarium-reared albino red-bellied pacu Piaractus brachypomus.

We report hirudiniasis caused by the leech Hemiclepsis marginata asiatica Moore, 1924 in albino red-bellied pacu (pirapitinga) Piaractus brachypomus (Cuvier, 1818), constituting the first documentation of a freshwater fish species being affected in India. The outbreak occurred in a tank of an aquarium-fish retailer; infested fish appeared asphyxiated, unable to swim or swimming upside down, with cloudy eyes and body with thick mucus secretion. The prevalence and mortality was 100%, with a mean intensity of 81 leeches per fish. The histopathology of the morbid fish revealed degenerative necrosis, eosinophilic infiltration in the muscle tissue and haemorrhages in the fin membrane. The leech mitochondrial 18S rDNA and 12S rDNA genes were characterised and submitted to GenBank under accession numbers MN380443 (18S) and MK733282 (12S). A maximum likelihood tree was constructed using 12S rDNA gene sequences to demonstrate the phylogenetic position of Hemiclepsis marginata asiatica among its congeners.

Intestinal histological alterations in farmed red-bellied pacu Piaractus brachypomus (Characiformes: Serrasalmidae) heavily infected by roundworms

The farmed red-bellied pacu Piaractus brachypomus is a valuative commercial fish widely exploited in fish farming. Histopathologic alterations in small intestine of this fish were associated with heavy roundworms infection. Of a total of thirty-five fish examined, all were parasitized with a prevalence of 100%, intensity of 290–6403, and mean intensity of infection of 4467.5 parasites per fish. According to the morphological features of whole nematodes examined using light and electronic microscopy, the parasite was identified as Rondonia rondoni Travassos. Rev Vet e Zoot 10, 59–70; 1920. The fish intestinal tissue alterations include fusion of villi, edema, disorganization of epithelial cells, epithelial abrasion, and flaking of the villus at mucosa layer level and submucosa layer with some regions of necrosis and lymphocyte infiltrate. This is the first report of histopathological alterations caused by infection of the atractid nematode R. rondoni in a farmed population of P. brachypomus in the Peruvian Amazon. The study points out the need of improving the strategies of parasitic prevention and control in order to better prevent future disease outbreaks.

About the capture of red-bellied pacu <i>Piaractus brachypomus</i> (Serrasalmidae) in the Lake Chervyachnoye (Sakhalin island)

An example of red-billed pacu Piaractus brachypomus with standard length 271.8 mm and weight 691 g was captured in the Lake Chervyachnoye (Sakhalin island) in May of 2010. This fish was without parasites, what indicates spending a short period in the Lake. Plenty fat in the abdominal cavity says in favour of good physical condition. Stomach content included typical Sakhalin freshwater invertebrates. The species does not threat local ecosystem, because minimum temperatures in the rivers and lakes of Sakhalin during cold period of the year are lower than red-billed pacu survival temperature limit. Most likely the fish was released into the lake by an amateur aquariumist.

Acid and Pepsin Soluble Collagens from Skin By-product of Red-bellied Pacu (Piaractus brachypomus): Extraction and Comparative Characterizations Towards Finding Substitute to Bovine and Porcine Collagen

ABSTRACT This investigation focused on the sustainable valorization of red-bellied pacu (RBP) skin towards finding an alternative to bovine and porcine collagen. Acid-soluble collagen (ASC, 45.8 ± 0.7%) and pepsin soluble collagen (PSC, 57.8 ± 1.9%) were successfully extracted from RBP skin and comparatively elucidated their characteristics and in-vitro fibril-forming potential. The extracted collagens were characterized as type I collagen and confirmed the well-preserved triple-helical configuration by sodium dodecyl sulphate polyacrylamide gel electrophoresis and Fourier transform-infrared spectroscopy analysis. Both ASC and PSC exhibited relatively better thermo-stability, and the denaturation temperatures were found to be 35.5–35.29 °C by differential scanning calorimetry analysis. Both collagens displayed higher (p ≤ 0.05) solubility at low NaCl concentrations. The extracted ASC and PSC showed the same degree of fibril-forming capacities and confirmed well-defined fibril morphologies. Overall, the results showed the possibilities of effectively exploring RBP skin as a potential alternative source for realistic and safe collagen for food, nutrition, pharmaceutical, and other applications.

Effects of short feed restriction cycles in Piaractus brachypomus juveniles

This work aimed to evaluate the effects of short feed restriction cycles on Piaractus brachypomus juveniles during the initial growth phase. A total of 750 fish (average initial weight of 2.4 g and density of 1 fish per 2 l of water) were distributed in 15 rectangular tanks maintained in a recirculation aquaculture system for 35 days. Fish were divided into three treatments: Control, fish continuously fed; 6F/1R, fish fed for six days and subjected to feed restriction for one day (on Sundays); and 5F/2R, fish fed for five days and subjected to feed restriction for two days (on Saturdays and Sundays). Fish were fed until apparent satiation two times a day (09 h00 and 16 h00) using an extruded commercial diet (2.6 mm diameter and 36% crude protein). There were no significant differences in survival among treatments (P > 0.05). Treatment 5F/2R had lower final weight, length, weight gain and specific growth rate compared to the control (P < 0.05), while these variables did not differ significantly from the control for the 6F/1R treatment. Food intake for both treatments submitted to feed restriction (6F/1R and 5F/2R) was lower compared to control. Feed conversion rate and protein efficiency ratio did not differ significantly among treatments (P > 0.05), nor did hematocrit and hemoglobin concentration (P > 0.05). Treatment 5F/2R had lower triglycerides than the control, while the other parameters (glucose and cholesterol) did not differ. Liver lipids, muscle lipids and the mesenteric fat index did not differ significantly among treatments (P > 0.05), however, the hepatosomatic index for 5F/2R was significantly lower than the control (P < 0.05). The adoption of short cycles of one day of feed restriction per week (treatment 6F/1R) appears to be a very satisfactory strategy in the production of juvenile P. brachypomus with an initial average weight of 2.4 g, as these animals showed good growth performance responses and did not experience changes in their hematological, biochemical and tissue parameters.

Salmonella in the processing line of farmed Tambatinga (Colossoma macropomum x Piaractus brachypomus) in Mato Grosso, Brazil: serotypes of occurrence and antimicrobial profile.

The objective of this study was to evaluate the dispersion dynamics and antimicrobial resistance profiles of Salmonella in the processing of Tambatinga (Colossoma macropomum x Piaractus brachypomus). Thirty fish were monitored during four processing stages (reception, first wash, evisceration, and prepackage area) in a fish slaughterhouse. One hundred and twenty fish surface samples were collected and tested through bacteriological analysis, PCR, serotyping, and antimicrobial resistance profile (disk-diffusion). Of these samples, 7.5% (9/120) were positive for Salmonella, with 0.83% being observed in the pre-packaging phase, indicating a low occurrence at this stage. All the analyzed stages were positive for Salmonella, with the prevalent serovars being Ndolo, Mbandaka, Typhimurium, Rough, and O:16. All strains were sensitive to various antimicrobials. Improvements in microbiological control during all processing stages should be implemented to ensure a Salmonella-free product.

Digestible threonine requirement in diets for tambatinga (♀Colossoma macropomum x ♂Piaractus brachypomus) fingerlings

ABSTRACT Cross breeding of native fish species is a technique to produce hybrids that can express higher weight gain and feed efficiency compared to the parental species. The digestible threonine requirement in diets for tambatinga fingerlings (Colossoma macropomum ♀ x Piaractus brachypomus ♂) was determined in this study. For this, 700 fingerlings with an average initial weight of 2.39 ±0.02 g and average final weight of 35.96 ±2.03 g were distributed in a completely randomized design consisting of six treatments (0.600, 0.800, 1.000, 1.200, 1.400, and 1.600% digestible threonine) and five replicates per treatment, with 20 fish per experimental unit. Diets were formulated by the “diet dilution” technique using the ideal protein concept. Performance, feed efficiency, body depositions of protein, ash and fat, and nitrogen retention efficiency of the fish were evaluated. The digestible threonine levels that optimized weight gain, specific growth rate, and feed conversion ratio were 1.40, 1.27 and 1.10%, respectively. Body deposition of fat was reduced in a quadratic manner (p&lt;0.01), and the body depositions of protein and ash, together with the efficiency of nitrogen retention, were optimized by the digestible threonine level of 1.20; 1.33, and 0.82%, respectively. The recommended digestible threonine level in the diet for tambatinga fingerlings is 1.20 to 1.40% (0.40 and 0.47% Mcal DE-1) to obtain higher body deposition of protein and weight gain, respectively.

Necroulcerative dermatitis associated with Myxobolus dermatoulcerans n. sp. (Cnidaria: Myxobolidae) in red-bellied piranha, Pygocentrus nattereri Kner (Characiformes: Serrasalmidae), from Peru.

A group of red-bellied piranha, Pygocentrus nattereri Kner, recently imported from Peru exhibited multifocal, cutaneous ulcerations with exposure of the underlying musculature. Skin scrapes yielded moderate numbers of myxospores morphologically consistent with Myxobolus Bütschli, 1882. Myxospores from these fish were morphologically and molecularly distinct from other myxobolids infecting piranha. Myxospores are pyriform to capsular with a rounded posterior and slightly rounded to tapering anterior aspect in valvular view. Myxospore bodies are 14.3-17.8 (mean 16.1) µm long and 7.6-10.3 (mean 8.9) µm wide. Polar capsules are symmetrical, slender, elongate, and measure 7.4-10.2 (mean 9.2) µm long and 2.1-3.7 (mean 3.0) µm wide. Sequence generated for the 18S rRNA gene had no direct matches to any sequence available on GenBank but demonstrated less than 89% nucleotide similarity to various published and unpublished Myxobolus spp. from Piaractus brachypomus (Cuvier) and Colossoma macropomum (Cuvier). This paper provides the morphological and molecular characterisation of Myxobolus dermatoulcerans n. sp. from red-bellied piranha and describes associated pathological lesions.