ABSTRACT
Nearly half of all vertebrates are fishes (over 25,000 known species in 515 families) (Nelson, 2006). In association with this great phylogenetic diversity is the enormous ecological diversity and unrivaled variation in physiology, life history pathways, and breeding systems (Breder and Rosen, 1966; Pitcher and Hart, 1983; Avise et al., 2002; Sloman et al., 2006). Indeed, studies of fishes have provided some of the greatest contributions to the field of behavioural ecology and have significantly enhanced our understanding of mating systems, parental care and reproductive strategies (Barlow, 1981, 2000; Warner, 1984; Gross and Sargent, 1985; Godin, 1997; Dugatkin, 2004; Alcock, 2006; Munday et al., 2006). Therefore, it
is all the more surprising that many behavioural ecologists are unaware that some fishes have interesting cooperative strategies. Although documented cooperation in fishes is rare, fishes have the potential to contribute greatly to our understanding of the evolution of cooperation in vertebrates. This is especially so because, in contrast to studies of birds and mammals, it is possible to study hundreds of fish groups of marked individuals in the field and in the laboratory (with small fish), as well as conduct large-scale experimental removals and introductions (BalshineEarn et al., 1998; Buston, 2004a, b; Stiver et al., 2004, 2005, 2006, 2007; Brouwer et al., 2005; Heg et al., 2005; Heg and Bachar, 2006; Desjardins et al., 2007).
