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This study evaluated the effect of temperature on growth of Austrolebias nigrofasciatus, an endemic and threatened annual killifish species of the Patos-Mirim lagoon system in Southern Brazil. In order to verify the effect of temperature on initial growth of A. nigrofasciatus, eggs stored in the laboratory were hatched and juveniles reared for eight weeks at 16 and 22 ºC. The standard length of newly hatched fishes was 4.67 ± 0.25 mm and after eight weeks they reached 23.68 ± 3.73 and 22.68 ± 5.36 mm, respectively at 16 and 22 ºC. However, initial growth of fish reared at 22 ºC was faster and they reached sexual dimorphism at an earlier age compared to those reared at 16 ºC. Final length of females reared at 22 ºC was 23.00 ± 2.83 mm, they were significantly larger than those reared at 16 ºC (17.91 ± 2.47 mm). Males were significantly larger than the females at 16 ºC, but there was no difference for growth between sexes of fish reared at 22 ºC. The sex ratios were 1:0.6 and 1:1.1 (M:F) at 16 ºC and 22 ºC, respectively, suggesting temperature determination of phenotypic sex. Considering the results, it appears that juveniles to be developed in captivity should be kept at 22 ºC during the first six weeks of life, thus ensuring a higher growth rate until puberty.

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...

The objective of the present study was to evaluate the growth performance of the shrimp Litopenaeus vannamei and the mullet Mugil platanus in earthen ponds (200 m²) located in the Laboratory of Continental Aquaculture of Universidade Federal do Rio Grande (FURG), in both polyculture and monoculture systems. The study consisted of three replicates, as follows: shrimp monoculture (SM), shrimp and mullet polyculture (PO) and mullet monoculture (MM). The stocking density was 10 post-larvae shrimp (PL) m −2 and 0.67 mullet m −2 . Fish and shrimp were fed commercial shrimp meal (38% crude protein) once a day. Initially, the amount of feed to shrimp was 20% of their total biomass which was later reduced to 5%. Mullets were fed at 5% of their stocked biomass. The experiment lasted 79 days during the summer of 2007/2008. At harvest, shrimp in monoculture had weight gain (15.59 g), specific growth rate (8.40% day −1 ), apparent feed conversion (0.88), survival (91%) and production (1.454 kg ha −1 ) significantly higher than in polyculture (1.039 kg ha −1 ). Mullets in polyculture had significantly better weight gain (42.72 g) and specific growth rate (3.99 % day −1 ) than those in monoculture (31.04 g and 3.69% day −1 , respectively), while the mullet condition factor was significantly smaller in polyculture (1.06) than in monoculture (1.13). The apparent feed conversion of the mullets did not present significant differences between monoculture (2.50) and polyculture (2.40). The physical and chemical water parameters were not significantly different in any of the experiments, except for the transparency, which was higher in earthen ponds with mullet monoculture. Polyculture of shrimp and mullet reared together in earthen ponds negatively affects the shrimp production and favors the production of mullets.