Morphological and behavioral development of the piracanjuba larvae

Abstract

-The objective of this work was to study the morphologic development and the swimming and feeding behaviors of piracanjuba larvae, Brycon orbignyanus Valenciennes (1849) (Characiformes, Characidae, Bryconinae), during the period from zero to 172 hours after hatching (standard length = 3.62 -11.94 mm). The morphological analyses were accomplished by using a trinocular stereo microscope, while the behavioral analyses were performed through periodic observations. In 28 hours after hatching, the larvae (standard length = 6.25 ± 0.13 mm) showed the following structural and behavioral characteristics that made them become active predators able to overcome a larval critical phase, the beginning of exogenous feeding: presence of pigmented eyes, terminal and wide mouth, developed oral dentition, developing digestive tube, yolk sac reduction, fins and swim bladder formation, horizontal swimming, cannibalism, and predation.Intense cannibalism among larvae was verified from 26 to 72 hours. At the end of the metamorphosis -172 hours after hatching -the larvae measuring 11.94 + 0.80 mm in standard length presented a flexed notochord, caudal fin bifurcation, dorsal and anal fin formation, synchronized movements, and formation of shoals, characteristics that together allow enhanced perception and locomotio in exploration of the environment, determining the best moment for transfering to the fishponds. New studies can contribute to commercial fish farming by improving feeding management, performance, survival, and productivity of this species.Key Words: behavior, Brycon orbignyanus, Characiformes, first feeding, morphology, ontogenyDesenvolvimento morfológico e comportamental de larvas de piracanjuba RESUMO -Objetivou-se estudar o desenvolvimento morfológico e os comportamentos natatório e alimentar de larvas de piracanjuba, Brycon orbignyanus Valenciennes (1849) (Characiformes, Characidae, Bryconinae) no período de 0 a 172 horas após a eclosão (comprimento-padrão = 3,62 -11,94 mm). As análises morfológicas foram realizadas com auxílio de um microscópio estereoscópico trinocular e as comportamentais, por meio de observações periódicas. Com 28 horas após a eclosão, as larvas (6,25 ± 0,13 mm) apresentaram características estruturais e comportamentais que as tornavam predadoras ativas, capazes de superar a etapa crítica da fase larval, o início da alimentação exógena: presença de olhos pigmentados, boca terminal e ampla, dentes desenvolvidos, tubo digestivo em desenvolvimento, saco vitelino em redução, nadadeiras e bexiga gasosa em formação, nado horizontal, canibalismo e predação. Canibalismo intenso entre as larvas foi verificado das 26 às 72 horas. No final da metamorfose, às 172 horas pós-eclosão, medindo 11, 94 + 0,80 mm de comprimento padrão, as larvas apresentaram notocorda flexionada, nadadeira caudal em bifurcação e nadadeiras dorsal e anal em formação, movimentos sincronizados e formação de cardumes, características que, em conjunto, permitem melhor percepção e locomoção na exploração do ambiente e determinam o m...

The effect of structural enrichment in hatchery tanks on the morphology of two neotropical fish species

“…Brycon orbignyanus is appreciated in commercial and sport fishing because of its active and aggressive behavior and the organoleptic properties of its meat (Vaz et al, 2000). In fish-farming it has good acceptance of artificial foods and agro-industrial by-products (Borba et al, 2006), but has high rates of cannibalism in the early stage of development, requiring feeding with post-larvae of other fish species (Reynalte-Tataje et al, 2002;Maciel et al, 2010).…”

Ontogeny and embryonic description of Betta splendens, Perciformes (Regan, 1910)

“…Information related to morphological development and morphometrical parameters, growth patterns and fish behavior are essential to understand the changes on physiological and ecological demands of each species and the factors that affect its performance (KOVAC & COPP, 1999;MACIEL et al, 2010;PEREZ-CASANOVA et al, 2006). Aquaculture is an activity that is expanding around the world as well as the ornamental fish production.…”

“…Description and knowledge of embryonic events of teleostei fish supply information to avoid malformation and high mortality, enhancing the management of incubation. Ontogeny of fish has been the scope for researchers due to the important contribution to the knowledge of initial phases, biology and taxonomy of species, and thus improving commercial larviculture, as well as the performance of fishculture ( FERREIRA et al, 2009;MACIEL et al, 2010). There is little information about embryonic development of ornamental fish in scientific literature, especially about B. splendens (GROTH, 1970).…”

Embryonic and larval development of Brycon amazonicus (SPIX & AGASSIZ, 1829)

“…The erratic vertical swimming is associated with the process of filling the bladder (Maciel et al, 2010). This behavior, associated with consecutive mandibular movements followed by frequent attacks at 34 h AF, could be associated with the mechanism for developing muscular and skeletal structures involved in the capture and arrest of the first food (Herbing, 2001).…”