Aim This study aimed to assist in guiding research with eggs and larvae of continental fish in Brazil, mainly in the knowledge of the early development, as well as to present the state of the art and to point out the gaps and future directions for the development of researches in the area. Methods The literature review was carried out in the electronic platforms and studies were examined to investigate whether any addressed morphological description of fish eggs and/or larvae. Results We found 121 studies, including scientific articles, theses, dissertations, chapters of books and books. This bibliographic production characterized 140 species, representing only 4.1% of the total species present in the Brazilian basins. Most of the species studied belong to the orders Characiformes and Siluriformes, which are of commercial interest and native to the Paraná, Amazon, Paraguay and Uruguay basins. For some very species-rich families in the Brazilian rivers, such as Characidae and Loricariidade, only a fraction of their species was characterized for the early development (2.6% and 0.7% of the total, respectively) and 56% of the families did not present any study addressing the early ontogeny. Regarding the content of the descriptions, for 73 species, there is characterization of the embryonic period and for 62, there is description of the whole larval period. For only 41 species there were complete descriptions (embryonic and larval) of the early development. All of these studies were conducted mainly with material derived from induced spawning and material obtained in the field (regressive series). Conclusions The characterization of eggs and larvae, still presents few studies, limited mainly to species from the rivers of the Plata and Amazon basins, to studies of fish of commercial importance and the incompleteness of most of these studies is still outstanding.
Studies on ichthyoplankton ecology become essential when one realizes the importance and influence of this component in dynamics, conservation, and maintenance of fishery resources. However, ecological information about this subject is still scarce and has not been properly valued and used by environmental managers and decision-makers. In this study, we present the state of the art of research on ichthyoplankton in the Amazon region. The number of studies has been increasing over time but they are scarce and restricted. We hope this study may encourage research related to ichthyoplankton in the Amazon region.
The ontogeny of the tetra fish Astyanax lacustris, from embryogenesis through the larval and juvenile periods, is presented. The eggs and larvae were obtained through induced reproduction. The larvae were collected at hatching and daily, until all stages of development were obtained and, later, once a week, until the juvenile period. The eggs are small, slightly adhesive and demersal, and have a transparent chorion, yellowish calf and meroblastic cleavage. The larvae hatch 19 hr after fertilization (26ºC). The standard length during initial development ranges from 2.17 to 18.10 mm. The larvae have a subterminal mouth, simple nostrils, a pair of adhesive organs on the back of the head (newborn larvae), spherical eyes and medium‐length intestines. The initial pigmentation is scarce, concentrated in the anteroposterior ends of the yolk sac, but intensifies from the flexion stage, with chromatophores in the mouth and in the cephalic region; the humeral region and the caudal peduncle have a macula at the end of the larval development. The total number of myomeres: 32–38, 15–20 preanal and 14–20 postanal. Juveniles showed similar morphology and pigmentation to adults. The number of fin rays: pectoral 11–12; pelvic 6–7; dorsal 10–11; and anal 27–29.
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