Arapaima gigas is an air-breathing giant fish of Amazonian rivers. Given its great economic and cultural importance, the aquaculture development of this species represents an evident solution to face the decline of wild populations. In captivity, reproduction occurs generally in large earthen ponds where stocks of a few tens of brooders are maintained together at the beginning of the rainy season (December-March in the Peruvian Amazon). Fry production relies on the spontaneous formation of male and female pairs, which build a nest, delimit a territory and guard the offspring for at least 20 days from other congeners and predators. However, as sex determination of A. gigas is not possible by morphological criteria, it is very difficult to optimize reproduction conditions and fry production in each pond, which seriously hampers the culture of this species. This situation prompted us to develop sexing methodologies based on (1) the detection of female specific plasma Vitellogenin (Vtg) using an enzyme immuno assay (EIA), and (2) the determination of plasma 17beta-estradiol and 11-ketotestosterone levels for immature specimens. The Vtg purification was performed by electro-elution after polyacrilamide gel electrophoresis (PAGE) from plasma of 17beta-estradiol treated A. gigas juveniles. Two different Vtg molecules were isolated, (Vtg(1) and Vtg(2)) with 184 and 112 kDa apparent molecular masses, respectively, and two antibodies were raised in rabbits for each Vtg molecule. Adult fish were 100% accurately sexed by Vtg EIA, while 100% of immature fish and 95% of adults were accurately sexed by 17beta-Estradiol and 11-Ketestosterone ratios. We also observed different color pattern development in male and female adult fish (6-year-olds) around the reproductive period.

The coefficients of the apparent digestibility for dry matter, crude protein, crude lipid and gross energy in cooked and raw green plantain meal (GPM), cassava root meal (CRM), and peach palm meal (PPM) were determined for juveniles of black pacu (60.8 ± 6.4 g) and red pacu (76.3 ± 5.0 g). The ADC of each alternative ingredient was determined by comparison of the digestibility (based on recovery of 1% chromic oxide as an inert marker) of a reference diet (consisting of 70% of test diet and 30% of the feedstuff) against with a test diet (24.5% of crude protein). Fish were bred in a recirculation system including 42, 110-L glass aquaria (21 tanks per species) at a density of five fish per tank, and fed their respective diets to apparent satiety, twice a day. Feces were collected after 10 days in plexiglass fecal collectors. Apparent digestibility coefficients of crude protein, crude lipid and gross energy from raw and cooked GPM and CRM were low compared to values to other common vegetal ingredients like corn and wheat. Conversely, ADC values for raw and cooked PPM were, in most cases, higher than those reported in raw or cooked GPM and CRM. In comparison with other traditional feedstuffs, apparent utilization of PPM was similar to corn and higher than reported for soybean meal and wheat bran in these fish species. Peach palm meal appears to have good potential as a feed ingredient in low-cost diets for pacu species.KEYWORDS: aquaculture, digestibility, feeding, red pacu, black pacu. COEFICIENTES DE DIGESTIBILIDAD APARENTE DE LOS NUTRIENTES Y LA ENERGÍA DE TRES INGREDIENTES VEGETALES ALTERNATIVOS CRUDOS Y COCIDOS EN Colossoma macropomum Y Piaractus brachypomus (SERRASALMIDAE) RESUMENLos coeficientes de digestibilidad aparente (ADC) para la materia seca, proteína cruda, lípidos y energía bruta en harinas obtenidas de porciones crudas y cocidas de plátano verde (GPM), yuca (CRM) y pijuayo (PPM) fueron determinados en juveniles de gamitana (60.8 ± 6.4 g) y paco (76.3 ± 5.0 g). El ADC de los ingredientes alternativos fue determinado por comparación de la digestibilidad (basada en la recuperación de óxido crómico como marcador inerte) de una dieta referencial (70% de dieta testigo y 30% del ingrediente en estudio) versus la dieta testigo (24.5% de proteína bruta). Los peces fueron criados en un sistema de recirculación compuesto de 42 acuarios de vidrio de 110 L (21 tanques para cada especie), a una densidad de cinco peces por tanque y alimentados con sus respectivas dietas hasta la saciedad aparente, dos veces por día. Las heces fueron colectadas a los 10 días en colectores fecales. Los niveles de ADC para proteína bruta, lípidos y energía bruta registrados para las harinas crudas y cocidas de plátano y yuca fueron bajas comparadas con las existentes para otros ingredientes como el maíz y el trigo. Sin embargo, los niveles de ADC obtenidos para las harinas crudas y cocidas del pijuayo fueron en la mayoría de los casos superiores a los reportados para el plátano y la yuca. En comparación con otros ingredientes ...

The number of larval instars of Simulium (Hemicnetha) rubrithorax Lutz (Diptera: Nematocera) was determined using the lateral length of the head capsule. In this study 1,035

Se describe el desarrollo larval del paiche Arapaima gigas en base a la caracterización de individuos nacidos y manejados en un sistema de recirculación en Iquitos, Loreto (Perú). Cada dos horas se tomaron fotografías a grupos de seis larvas con el apoyo de cámaras conectadas a microscopios y estereoscopios. Las fotografías fueron analizadas en Image J obteniéndose medidas de longitud de estructuras y órganos según éstas iban apareciendo y desarrollándose en cada fase. Se registró el tiempo de aparición de cada nueva estructura. Las larvas fueron caracterizadas desde la eclosión hasta las 196 horas post eclosión (hpe). Las larvas de paiche miden 14.46 ± 0.34 mm al momento de la eclosión (0 hpe) y alcanzan 19.12 ± 0.55 mm  a los 196 hpe. El diámetro horizontal del saco vitelino significa el 82.8% de la longitud total del cuerpo de la larva al momento de la eclosión y es absorbido casi por completo a las 194 hpe (8 días de edad), cuando los individuos miden 19.1 ± 0.55 mm y pueden ser considerados alevinos. A las 103 hpe las larvas de A. gigas emergen por primera vez a la superficie, iniciando la alimentación exógena a las 146 hpe, tiempo que coincide plenamente con las observaciones de campo reportadas por piscicultores locales en Loreto y Ucayali

Cytotaxonomic studies of black flies have repeatedly demonstrated the value of chromosomal characters in elucidating phylogenetic relationships, revealing sibling species and providing diagnostic aids for species identification (Rothfels 1988, Adler et al. 2004). In Brazil, numerous black flies have been investigated cytotaxonomically (e.g., Campos et al. 1996, Charalambous et al. 1996, Hamada & Adler 1999, Luz 1999, Ríos-Velásquez et al. 2002, Pereira 2004. While chromosomal studies are often essential in revealing sibling species and resolving relationships, the strongest taxonomic and phylogenetic resolution of black flies comes from a combined chromosomal-morphological approach. This approach has permitted an analysis of species diversity in the Amazon Basin that is more critical than has been possible using the conventional morphotaxonomic approach alone.Various subgeneric classifications have been used for Neotropical black flies. Crosskey and Howard (1997) and Crosskey (2002), for example, recognize the Neotropical subgenus Psaroniocompsa, with 38 species and 5 species groups. Py-Daniel (1983) and Coscarón (1987) subgenera Cerqueirellum and Coscaroniellum, respectively. Py-Daniel and Sampaio (1995) ranked these two subgenera as genera. Cytogenetic techniques can provide independent assessments of these phylogenetic hypotheses and yield insight into classification issues.The objective of the present study is to resolve the chromosomal differences between Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz, two members of the subgenus Psaroniocompsa (Crosskey & Howard 1997), and to evaluate the usefulness of morphological discriminators previously used for the larvae. S. cauchense is known from Brazil, French Guiana, Guyana, and Venezuela, whereas S. quadrifidum, with a slightly broader distribution, is known from Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Suriname, and Venezuela. MATERIALS AND METHODSLarvae were collected from 15 streams in the states of Amapá, Amazonas, Rondônia, and Roraima (Fig. 1). S. quadrifidum was collected at 13 sites and S. cauchense at 6; the latter species was not collected in the state of Rondônia. Most collections were made in 2000 and 2001, although two collections were made in 1997 and one each was made in 1996, 1999, 2002, and 2003 (Table I).Larvae were hand collected from all available substrates and fixed in Carnoy's solution (1 part glacial acetic acid: 3 parts absolute ethanol); the fixative was changed 3 or 4 times in the field and the samples were maintained on ice. In the laboratory, the fixative was changed once more and the samples were held at 4°C, pending chromosomal analysis. The following morphological characters of final-instar larvae were evaluated for their utility in species identification: presence of dark spots on the cephalic rays (PyDaniel 1983), branching pattern of the dorsal abdominal setae (Hamada et al. 2003), body pigmentation pattern, and branching pattern of the gill histoblast (Shelley et al. 1997, Hamada & Gri...