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

Abstract

The objective of this study was to describe the embryonic and larval development of Brycon amazonicus, featuring the main events up to 50 hours after fertilization (AF). The material was provided by the Aquaculture Training, Technology and Production Center, Presidente Figueiredo (AM). The characterization was based on stereomicroscopic examination of the morphology of eggs, embryos and larvae and comparison with the literature. Matrinxã eggs are free, transparent, and spherical, with a perivitelline space of 0.56 ± 0.3 mm. The successive divisions give rise to cells with 64 blastomeres during the first hour AF. The gastrula stage, beginning 02 h 40 min AF, was characterized by progressive regression cells and the formation of the embryonic axis, leading to differentiation of the head and tail 05 h 30 min AF. From 06 to 09 h AF the somites, notochord, otic and optic vesicles and otoliths were observed, in addition to heart rate and the release of the tail. The larvae hatched at 10 h 30 min AF (29.9 °C), with a total length of 3.56 ± 0.46 mm. Between 19 and 30 h AF, we observed 1) pigmentation and gut formation, 2) branchial arches, 3) pectoral fins, 4) a mouth opening and 5) teeth. Cannibalism was initiated earlier (34 h AF) which was associated with rapid yolk absorption (more than 90% until 50 h AF), signaling the need for an exogenous nutritional source. The environmental conditions (especially temperature) influenced the time course of some events throughout the embryonic and larval development, suggesting the need for further studies on this subject.Keywords: matrinxã, embryogenesis, oocytes. Desenvolvimento embrionário e larval de Brycon amazonicus (SPIX & AGASSIZ, 1829)Resumo O objetivo deste trabalho foi descrever o desenvolvimento embrionário e larval do Brycon amazonicus, caracterizando os principais eventos ocorridos até 50 h Após Fertilização (AF). O material é proveniente do Centro de Treinamento, Tecnologia e Produção em Aqüicultura em Presidente Figueiredo (AM). A caracterização foi feita com base na análise estereomicroscópica da morfologia dos ovos, embriões e larvas e comparação bibliográfica. Os ovos da matrinxã são livres, transparentes, esféricos com espaço perivitelínico de 0,56 ± 0,3 mm. As sucessivas clivagens originam células com 64 blastômeros na primeira hora AF. A gástrula, iniciada 02 h e 40 min AF caracterizou-se por progressiva involução celular e formação do eixo embrionário, culminando com diferenciação de cabeça e cauda com 05 h 30 min AF. De 06 às 09h AF foi observada a formação de somitos, notocorda, vesículas óptica, ótica e otólitos, além de batimentos cardíacos e liberação da cauda. As larvas eclodiram com 10 h 30 min AF (29,9 °C), com 3,56 ± 0,46 mm de comprimento total. Entre 19 e 30 h AF foram observadas: 1) pigmentação e formação do tubo digestivo 2) surgimento de arcos branquiais 3) nadadeira peitoral 4) abertura da boca e 5) surgimento dos dentes. O canibalismo iniciou mais precocemente (34 h AF), em relação aos trabalhos existentes com o gênero, o que associa...

Larval development of Brycon amazonicus (Teleostei, Bryconidae) with a focus on locomotory, respiratory and feeding structures

“…Nakauth et al . () observed that B. amazonicus larvae at 33 hph also have a partially pigmented retina and continuous movements of the jaw. These characteristics demonstrate that at this period B. amazonicus larvae are capable of active predation, which may initially result in high energy expenditure, which probably accelerates yolk‐sac consumption, already greatly reduced by then, leading to complete expenditure after a few hours.…”

Effect of body size heterogeneity on the aggressive behavior of larvae of matrinxã, Brycon amazonicus (Characiformes, Bryconidae)

“…For example, skeletal ossification of pacu (Piaractus mesopotamicus) larvae is complete when larvae reach 40 post-hatching days (DPH) (Portella et al 2014), whereas in Brycon orbignyanus ossification is complete in larvae with 7 DPH (Maciel et al 2010). Thus, the fast larval development in B. amazonicus (e.g., Neumann 2008;Nakauth et al 2016) may modulate the display of aggressive behavior in this species.…”

“…Matrinxã larvae hatch 10.5 hours after fertilization, exhibiting erratic vertical swimming characterized by upward movement, followed by constant sinking in the water column (Nakauth et al 2016). The oral cavity opens at 18 HAH, the mouth of larvae is completely opened, with sharp teeth and start of cannibalism at 30-34 HAH, 40 -70% of the yolk sac is apparently absorbed at 40 HAH, and more than 90% of the calf is absorbed at 60 HAH, with swim bladder inflation and horizontal swimming, suggesting greater control of swimming activity (Nakauth et al 2016). The early stages of development affected individual aggression in both our treatments, with highest rates of aggressive behavior observed at 12 HAH.…”

Ontogeny of the digestive tract of Brycon amazonicus (Teleostei, Bryconidae) under culture conditions: from hatching to juvenile stage

“…One of the biggest problems in the culture of this species is related to high mortality at the larval stage when cannibalistic behaviour has been indicated as the main cause of death (Leonardo et al, 2008). However, other reasons are also related to low survival in the larviculture, such as lack of knowledge about their ontogeny, inadequate nutrition composition of fish foods, bad environmental conditions and unknown digestive capacity (Cuenca-Soria et al, 2013;Nakauth et al, 2016;Alveal et al, 2019). Upon hatching, fish larvae nutrition occurs through absorption from the yolk sac and, generally, their organic systems are simple and incomplete.…”