MATURAÇÃO OVARIANA DE Astyanax altiparanae APÓS DESOVA EM SISTEMA DE RECIRCULAÇÃO DE ÁGUA

Abstract

In this study, we evaluated the possibility of obtaining successive Astyanax altiparanae spawns under laboratory conditions. In order to do so, 104 specimens were randomly distributed into four boxes (10 females and 16 males each) and kept in a recirculation system at an average temperature of 29.24 ± 0.42 °C, under natural photoperiod, for 30 days. On the onset of the experiment, males and females were induced for reproduction with a 6 mg kg-1 carp pituitary extract dose. After that, ovary (for gonadosomatic index and stereological assessment) and blood samples (for steroid evaluation) were collected from eight females (two per box) at the following moments: immediately after hormonal induction (day 0) and on days 1, 6, 16 and 30 after spawning. On day 6, spawned females presented complete mature ovaries similar to those on day 0 and, in this period, we did not observe postovulatory complexes, indicating that their resorption happened very fast. Concomitantly, the steroid levels increased gradually up to day 6, which corroborated an intense vitellogenic activity in this period. This study has demonstrated that A. altiparanae females are suitable for induced spawning within six days after spawning, when kept at 29.24 ± 0.42 °C, in a system maintained with recirculated water.

Reproductive cycle of the Amazonian planktivorous catfish Hypophthalmus marginatus (Siluriformes, Pimelodidae)

“…The occurrence of migratory species with a reproductive cycle similar to that of total spawners (with a demarcated spawning season and a long resting period) but presenting characteristics of asynchronous oocyte development has already been described, especially for small‐ to medium‐sized species, such as Astyanax altiparanae (Cassel et al, ), Rhamdia quelen (Reidel, Boscolo, Feiden, & Romagosa, ) and Rhamdia voulezi (Bittencourt et al, ). However, even though they may spawn more than once within the same reproductive season, these previously measured species respond positively to hormonal treatments used for total spawning species, which normally include two doses of crude carp pituitary extract (Lira et al, ).…”

“…Nevertheless, the possibility of spawning in the studied area cannot be completely excluded because the duration of the process of postovulatory complex reabsorption is usually rapid and difficult to identify by sampling from the natural environment. In Centropomus undecimalis , the resorption process has been thoroughly investigated, and the disappearance of the complexes has been described to occur 48 hr post spawning (Grier et al, ); furthermore, the process seems to take a few days in the few tropical migratory fish studied, such as Pseudoplatystoma fasciatum (Romagosa, Batlouni, Borella, & Leonardo, ), Astyanax bimaculatus lacustris (Drummond, Bazolli, Rizzo, & Sato, ) and Astyanax altiparanae (Lira et al, ). It is, therefore, possible that spawned females were not found in this study due to the sampling frequency.…”

“…However, even though they may spawn more than once within the same reproductive season, these previously measured species respond positively to hormonal treatments used for total spawning species, which normally include two doses of crude carp pituitary extract (Lira et al, 2018).…”

“…The results of the volume density evaluation were used to define the ovarian maturation stage, following traditional methodology applied for describing the reproductive cycle of tropical migratory (Borella, Chehade, Costa, & Batlouni, ; Rizzo & Bazolli, ) and other fish (Grier, Neidig, & Quagio‐Grassioto, ; Mañanós, Duncan, & Mylonas, ). To determine reproductive classes, we used the data obtained by volume density following methodology applied with some adjustments for the species under study (De Almeida et al, ; Kuradomi, Foresti, & Batlouni, ; Lira, Kuradomi, Souza, Hainfellner, & Batlouni, ; Pereira et al, ). Briefly, ovaries predominantly occupied by PV and lacking VI were considered "resting/immature"; ovaries presenting PV, CA and VI (volume density <10%) were considered "in maturation"; ovaries presenting VI (volume density >20%) and lacking POF were considered "mature"; ovaries with the presence of POF and VI were considered "spawned"; and ovaries that presented AT (>10%) were defined as "atretic.…”

“…The results of the volume density evaluation were used to define the ovarian maturation stage, following traditional methodology applied for describing the reproductive cycle of tropical migratory (Borella, Chehade, Costa, & Batlouni, 2014;Rizzo & Bazolli, 2014) and other fish (Grier, Neidig, & Quagio-Grassioto, 2017;Mañanós, Duncan, & Mylonas, 2008). To determine reproductive classes, we used the data obtained by volume density following methodology applied with some adjustments for the species under study (De Almeida et al, 2018;Kuradomi, Foresti, & Batlouni, 2017;Lira, Kuradomi, Souza, Hainfellner, & Batlouni, 2018;Pereira et al, 2017).…”