Larval development of the Mexican Snook, Centropomus poeyi (Teleostei: Centropomidae)

We document for the first time the early ontogeny of Centropomus poeyi based on captive raised material representing 0-19 days posthatch (dph). The achievement of early developmental landmarks (i.e., yolk-sac depletion, flexion, development of fins) and changes in pigmentation are described (1.4 mm NL-10.6 mm SL; 0-19 dph) and documented for a subset of individuals using high quality photographs. The ontogeny of the viscerocranium is also described (2.4 mm NL-10.6 mm SL; 6-19 dph). Development in C. poeyi occurs over a short period with attainment of the juvenile stage (i.e., full complement of fin rays present in each fin) occurring by 6.9 mm SL. The ontogeny of external pigmentation in C. poeyi is marked by two trends throughout growth: (1) a decrease in pigmentation dorsally; and (2) an increase in pigmentation ventrally along the midline. Development of the viscerocranium begins with the appearance of the maxilla and dentary in individuals of 2.4 mm NL, coinciding with the depletion of the yolk-sac. By 10.6 mm SL all bones of the viscerocranium are present and teeth are present on all teeth-bearing bones of the adult. Aspects of early development in C. poeyi are compared with the congeners C. undecimalis and C. parallelus.(AU)

Se documentó por primera vez la ontogenia temprana de Centropomus poeyi basada en material obtenido de cautiverio a partir de embriones (0 días después de la eclosión, dde) hasta los 19 dde. Se registró la aparición de puntos de referencia en el desarrollo temprano (p.ej. consumo de saco vitelino, flexión, desarrollo de aletas) y los cambios de pigmentación han sido descritos (1.4 mm NL-10.6 mm SL; 0-19 dde), siendo documentado para un subgrupo de individuos utilizando fotografías de alta calidad. El desarrollo del viscerocráneo también fue descrita (2.4 mm NL-10.6 mm SL; 6-19 dde). El desarrollo en C. poeyi sucede en un periodo corto de tiempo hasta alcanzar una etapa juvenil (p.ej., aparición completa de los radios presentes en cada aleta), lo que se observa a los 6.9 mm SL. La pigmentación externa en C. poeyi esta marcada por dos tendencias en el crecimiento: (1) un descenso en la pigmentación dorsal; y (2) un incremento en la pigmentación ventral a lo largo de la línea media. El desarrollo del viscerocráneo comienza con el aparecimiento del maxilar y el dentario en individuos de 2.4 mm NL, lo cual coincide con el consumo del saco vitelino. A los 10.6 mm SL todos los huesos del viscerocráneo están presentes como se observa en los dientes en los adultos. Algunos aspectos del desarrollo temprano en C. poeyi son comparados con los congéneros C. undecimalis y C. parallelus.(AU)

The seasonal diet of Aequidens tetramerus (Cichlidae) in a small forest stream in the Machado River basin, Rondônia, Brazil / Dieta sazonal de Aequidens tetramerus (Cichlidae) em um igarapé da bacia do rio Machado, Rondônia, Brasil

Trophic relationships in fish communities are affected by the availability of resources, which in turn is affected by spatial and temporal variations throughout the year. The aims of this study were to characterize the diet of A. tetramerus in a streamlet in the north of Brazil and compare its composition in different hydrological seasons (wet and dry seasons). Collections were performed every two months from October 2011 to September 2012 with the aid of seine nets, hand net and fishing traps in the streamlet located in the Machado River drainage basin in the Rondônia state. Most of the specimens collected were quite small (<40 mm) and had empty stomachs. Our results showed that A. tetramerus feeds on a wide variety of items of plant origin, such as algae, seeds and leaves, as well as items of animal origin, including bryozoans, crustaceans, fish scales, terrestrial insects and detritus. The data also indicated higher consumption of aquatic insects than other food items, suggesting a primarily insect-based diet. Items of plant and allochthonous origin were consumed more in the wet season than in the dry season, but there were no seasonal differences in the consumption of animal and autochthonous items.

Relações tróficas das comunidades de peixes são afetadas por variações espaciais e temporais, que alteraram a disponibilidade de recursos ao longo do ano. Os objetivos deste estudo foram caracterizar a dieta de A. tetramerus no igarapé estudado, bem como comparar se a composição dos itens da dieta desta espécie dependem da estação hidrológica (período chuvoso e seco). As coletas foram realizadas bimestralmente, de Outubro de 2011 a Setembro de 2012, com auxílio de picaré, puçá e covos em um igarapé localizado na bacia do rio Machado no estado de Rondônia. A maioria dos espécimes eram pequenos (<40 mm) e tinham estômago vazio. Observou-se que A. tetramerus se alimenta de uma grande variedade de itens de origem vegetal, como algas, sementes e folhas; e de itens de origem animal como: briozoários, crustáceos, escamas, insetos terrestres e detritos. Constatou-se que há maior consumo de insetos aquáticos, o que sugere uma dieta insetívora. Itens de origem vegetal e alóctones foram mais consumidos na estação chuvosa do que na estação seca. Não houve diferença na composição da dieta dos peixes entre as estações de seca e chuva.

Fecundity, growth, and survival of the angelfish Pterophyllum scalare (Perciformes: Cichlidae) under laboratory conditions

The freshwater angelfishes (Pterophyllum) are South American cichlids that have become very popular among aquarists, yet scarce information on their culture and aquarium husbandry exists. We studied Pterophyllum scalare to analyze dietary effects on fecundity, growth, and survival of eggs and larvae during 135 days. Three diets were used: A) decapsulated cysts of Artemia, B) commercial dry fish food, and C) a mix diet of the rotifer Brachionus plicatilis and the cladoceran Daphnia magna. The initial larval density was 100 organisms in each 40L aquarium. With diet A, larvae reached a maximum weight of 3.80g, a total length of 6.3 cm, and a height of 5.8cm; with diet B: 2.80g, 4.81cm, and 4.79cm, and with diet C: 3.00g, 5.15cm, and 5.10cm, respectively. Significant differences were observed between diet A, and diet B and C, but no significantly differences were observed between diets B and C. Fecundity varied from 234 to 1 082 eggs in 20 and 50g females, respectively. Egg survival ranged from 87.4% up to 100%, and larvae survival (80 larvae/40L aquarium) from 50% to 66.3% using diet B and A, respectively. Live food was better for growing fish than the commercial balanced food diet. Fecundity and survival are important factors in planning a good production of angelfish. Rev. Biol. Trop. 57 (3): 741-747. Epub 2009 September 30.

Se realizaron estudios de cultivo en laboratorio del pez ángel, Pterophyllum scalare, para analizar los efectos de su dieta en la fecundidad, crecimiento y sobrevivencia en huevos y larvas por un período 135 días. Tres dietas diferentes se utilizaron A) quistes decapsulados de Artemia, B) comida comercial seca para pez, C) una mezcla de rotíferos, Brachionus plicatilis y el cladocero, Daphnia magna. La densidad inicial de larvas en acuarios de 40L fue de 100 organismos. Utilizando la dieta A, las larvas alcanzaron un peso máximo de 3.80g, una longitud total de 6.3cm y una altura de 5.8cm; utilizando la dieta B, fue de 2.80g, 4.81cm y 4.79cm y con la dieta C, fue de 3.00g, 5.15cm y 5.10cm, respectivamente. Diferencias significativas se observaron entre la dieta A y las dietas B y C. La fecundidad varió de 234 a 1082 huevos en hembras de 20 y 50g, respectivamente. La sobrevivencia de los huevos varió de 87.4% a 100% y la sobrevivencia de las larvas (80 larvas por acuario de 40L) varió entre 50 y 66.3% con las dietas B y A, respectivamente. Los resultados indicaron, que la comida viva fue mejor para el crecimiento de los peces, que los alimentados con la comida comercial balanceada. La fecundidad y la sobrevivencia son factores importantes para la planificación de una buena producción del pez ángel.

Ptereleotris carinata, a new species of hovering goby (Perciformes: Microdesmidae) from the tropical eastern Pacific

A new hovering goby or dartfish is described from material collected in Mexico, Costa Rica and Panama. It is the only species of the cosmopolitan genus Ptereleotris known from the eastern Pacific. It is distinguished from its Western Atlantic and Indo-Pacific congeners by its low fin-ray counts, prominent median keel on the ventral margin of the head, lanceolate caudal fin with dusky lower half and dusky blue or lavender body in adults.