Induced spawning and reproductive variables of the catfish Lophiosilurus alexandri Steindachner, 1876 (Siluriformes: Pseudopimelodidae)

Abstract

Lophiosilurus alexandri is an endemic fish from the São Francisco River basin, Brazil. The aim of this study was to induce L. alexandri to spawn and to obtain data on several reproductive variables for this species. For induced spawning, adults were submitted to Cyprinus carpio pituitary homogenate (CPH). Nine of the 12 females (75%) responded positively to the treatment. The stripping of oocytes was performed 8.4 h after the second dose of CPH with the water temperature maintained at 26ºC. The number of stripped oocytes per gram of ova was 74 ± 5 oocytes g -1, and the mean oocyte diameter was 3.1 ± 0.2 and 3.6 ± 0.2 mm, before and after hydration, respectively. The oocytes were opaque, yellowish, demersal, highly adhesive, and covered by a gelatinous coat. The total fecundity was 4,534 ± 671 oocytes, and the fertilization rate was 59%. The initial and final fertilities were 2,631 ± 740 and 1,542 ± 416 embryos, respectively. Larval hatching occurred up to 56 h after fertilization, and the larvae had a total length of 8.4 ± 0.1 mm. This work provides important biological information for L. alexandri that can be used for management and conservation of this species.Lophiosilurus alexandri é um peixe endêmico da bacia do rio São Francisco, Brasil. O objetivo do trabalho foi induzir L. alexandri à desova e obter dados sobre várias variáveis reprodutivas para esta espécie. Para desova induzida, adultos foram submetidos ao homogeneizado de hipófise de Cyprinus carpio (HHC). Nove das 12 fêmeas (75%) responderam positivamente ao tratamento. A extrusão dos ovócitos aconteceu 8,4 h após a segunda dose de HHC com a temperatura da água mantida a 26ºC. O número de ovócitos liberados por grama de ova foi de 74 ± 5 ovócitos g -1 e a média do diâmetro ovocitário foi de 3,1 ± 0,2 e 3,6 ± 0,2 mm, antes e depois da hidratação, respectivamente. Os ovócitos foram opacos, amarelo-castanho, demersais, altamente adesivos e revestidos por capa gelatinosa. A fecundidade total apresentou 4.534 ± 671 ovócitos e a taxa de fertilização foi de 59%. As fertilidades inicial e final foram de 2.631 ± 740 e 1.542 ± 416 embriões, respectivamente. A eclosão das larvas aconteceu até 56 h após a fertilização e as larvas tiveram comprimento total de 8,4 ± 0,1 mm. Este trabalho fornece informações biológicas importantes para L. alexandri, que podem ser utilizadas para o manejo e conservação desta espécie.

Capture, adaptation and artificial control of reproduction of Lophiosilurus alexandri: A carnivorous freshwater species

“…Reproduction in this species occurs between October and February (Sato et al, 2003a;Barros et al, 2007) with the males of the species caring for the egg mass (Sato et al, 2003b). The fecundity of this species is less than for many aquatic species but consistent with fecundity rates of species with the sedentary nature of this species (Santos et al, 2013). The size of vitelogenic oocytes of L. alexandri are large and have highly adhesive characteristics (Bazzoli and Godinho, 1997;Rizzo et al, 2002;Guimarães-Cruz et al, 2009;Santos et al, 2013).…”

“…The fecundity of this species is less than for many aquatic species but consistent with fecundity rates of species with the sedentary nature of this species (Santos et al, 2013). The size of vitelogenic oocytes of L. alexandri are large and have highly adhesive characteristics (Bazzoli and Godinho, 1997;Rizzo et al, 2002;Guimarães-Cruz et al, 2009;Santos et al, 2013). However, reproduction in controlled conditions has not been studied for this species.…”

The effect of environmental colour on the growth, metabolism, physiology and skin pigmentation of the carnivorous freshwater catfish Lophiosilurus alexandri

“…The pacamã Lophiosilurus alexandri Steindachner 1876 is a Siluriformes much appreciated for its meat. The breeding and raising of its larvae can be successfully carried out under laboratory conditions (Luz & Santos, ; Guimarães‐Cruz et al , ; Santos & Luz, ; Santos et al , ; Melillo Filho et al , ; Costa et al , ). Pedreira et al (), however, stated the use of green tanks can compromise the use of live food during larval rearing of this species, but to date, the effects of how the environmental colour can influence the performance and well‐being of juveniles is unknown.…”

<b>Long-term transportation of juvenile pacamãs <i>Lophiosilurus alexandri</i> at different densities

“…Its larviculture has been well studied (Luz & Santos 2008;Santos & Luz, 2009;Luz, Santos, Pedreira, & Teixeira, 2011;Pedreira, Sampaio, Santos, & Pires, 2012;Santos, Sampaio, Arantes, & Sato, 2013), but it is necessary to know the tolerance of this species to transportation, since it is commonly used in restocking programmes. Transportation of juveniles of this species has been successfully performed but only for a short period of 7.5 hours (Luz, Costa, Ribeiro, Silva, & Rosa, 2013), and it is important to evaluate longer times.…”