Fighting Fish (Betta splendens) Bubble Nests Do Not Inhibit Microbial Growth

Abstract

Some organisms produce antimicrobial substances in nesting foam to favorably manipulate the environment to which their developing offspring are exposed. We tested if fighting fish Betta splendens foamy nest material, which is comprised of bubbles produced in the oral cavity of nesting males, has antimicrobial properties against a pathogenic bacteria (Edwardsiella tarda), a nonpathogenic bacteria (Escherichia coli), or a pathogenic oomycete (Saprolegnia parasitica). We also tested if exposure to nest material increases larval survival by performing in vitro fertilizations and individually incubating eggs in bubble nest extract or tank water (control). Our results show no evidence of antimicrobial properties of bubble nests. On the contrary, bubble nests provided favorable microenvironments for the growth of Saprolegnia parasitica. Our results confirm earlier work citing the importance of male nest attendance, and suggest that the mechanism responsible for decreased survival in the absence of attending males is pathogenic microbes. J. Exp. Zool. 317A:481‐487, 2012. © 2012 Wiley Periodicals, Inc.

Water mold infection but not paternity induces selective filial cannibalism in a goby

“…Common pathogens include water molds (oomycetes) of the genus Saprolegnia, which infect adults and eggs alike and pose a serious threat to egg viability (Hussein & Hatai, 2002;Kitancharoen, Hatai, & Yamamoto, 1997;Knouft, Page, & Plewa, 2003;Scott & O'Bier, 1962;van West, 2006). In the absence of brood care, eggs often rapidly overgrow with water mold hyphae and die quickly (Bronstein, 1982;Brown & Clotfelter, 2012). The caring male may actively prevent infections, for example, by secreting a protective mucus (Giacomello, Marri, Marchini, Mazzoldi, & Rasotto, 2008;Knouft et al, 2003) or by creating a constant water flow via egg fanning (Côté & Gross, 1993;St Mary, Gordon, & Hale, 2004).…”

How sexual and natural selection interact and shape the evolution of nests and nesting behaviour in fishes

“…Their floating nests are built from bubbles produced in the buccal cavity, covered with glycoprotein mucus [ 111 , 145 ]. Unlike gobies and darters, this mucus does not appear to have antimicrobial functions [ 146 ]. In nests of male fighting fish, Betta splendens , collected from nature, male length and weight correlate with nest size.…”