First, it is well known that energy reserves decline during the breeding season, and that fishes that have not reproduced have higher energy reserves at the end of the breeding season than fishes that have reproduced. Second, many studies manipulate diet or ration, and these studies show that individuals that receive more supplemental food have higher reproductive success, survival between brood cycles, or both. For example, during male-male competition for females in fishes, larger males court females, whereas smaller males attempt to mate forcibly or sneakily. The fathead minnow, Pimephales promelas , is a small North American cyprinid fish with exclusive male parental care. Fantail darters, Etheostoma flabellare , are small North American percid fishes with exclusive male parental care.
Males develop ornaments on their first dorsal fins that are thought to be be egg mimics.
We found that females prefer males with eggs and males with their egg mimics intact over males whose egg mimics have been removed. Preliminary data suggest that at the beginning of the breeding season that the partial correlation coefficients between egg mimic size, body weight, and extracted fat weight, all adjusted for body length, are significantly positive. The convict cichlid, Cichlasoma nigrofasciatum , is a small Central American cichlid fish that is characterized by biparental care. My graduate student, Kasi Jackson , currently is investigating whether sexual selection operates in both sexes simultaneously, and whether female breeding coloration may have evolved as an honest signal.