Conspicuous coloration of males occurs in many species of fish, birds and other animals being advantageous in attracting potential mates. Although bright colors can entice females of the same species, these colors may also attract predators. Female choice for bright males and an enhanced risk of predation for bright males are both well documented in numerous works (see Dill et al., 1999, and references therein).

Because fresh waters are optically turbid in comparison with pure sea waters, curves of photopic spectral sensitivity in freshwater fish are strongly displaced to the red part of the spectrum. For example, the maximum of spectral sensitivity in threespined stickleback, Gasterosteus aculeatus, is near 605 nm (Rowe et al., 2004). It means that for eyes of freshwater fish red and orange colors are brighter than all other equipower monochromatic colors, and this feature occurs in nuptial signaling coloration.

The nature allows males of freshwater fish to practice several strategies to find trade-offs between conspicuousness for sexual mates and crypticity for potential predators, including plasticity in nuptial color development (e.g., Endler, 1983; Candolin, 1998; Ruell et al., 2013). In this context, an ability to develop bright red and orange colors in the under less illuminated parts of the fish’s body, in conformity with the theory of color countershading in fresh waters, is the primary.

Indeed, red and orange colors occur in breeding males just in the under parts of their bodies such as breast, ventral part, belly and the lower fins. An important role of this elements in nuptial coloration of males is documented in guppy, Poecilia reticulata (Endler, 1983; Kodric-Brown, 1985), and other species of genus Poecilia, threespined stickleback, G. aculeatus (Rowe et al., 2004), European bitterling, Rhodeus sericeus (Candolin & Reynolds, 2001), and in other spesies of genus Rhodeus, as well as in males of other freshwater fish. In some cases red and orange colors occur in the upper most illuminated parts of the fish’s body, but patterns of this type will be considered separately.

According to Kodric-Brown (1998), breeding males with red fins occur in many families of North American freshwater fish, including minnows (Cyprinidae), suckers (Catostomidae), killifish (Fundulidae), sunfish (Centrarchidae), darters (Percidae) aa well as cichlids (Cichlidae).

Generally, bright red and orange colors are conspicuous at the shot distance for sexual mates, but are cryptic in the countershading complex at the longer (that is optically thick) distances for potential predators. According to Evans & Norris (1996), red pigmentation of the fish’s body cannot be assessed accurately under green light or hereof if viewed through the water column, as the natural green filter.

Vorobyev et al. (2001) demonstrate how fish can see other fish through the water column.

Basic References

Candolin U. 1998. Reproduction under predation risk and the trade-off between current and future reproduction in the threespine stickleback. Proceedings of the Royal Society, Biological Sciences 265, 1171-1175

Candolin U., Reynolds J.D. 2001. Sexual signaling in the European bitterling: females learn the truth by direct inspection of the resource. Behavioral Ecology 12, 407-411

Dill L.M., HedrickA.V., Fraser A. 1999. Male mating strategies under predation risk: do females call the shots? Behavioral Ecology 10, 452-461

Endler J.A. 1983. Natural and sexual selection on color patterns in poeciliid fishes. Environmental Biology of Fishes 9, 173-190

Evans M.R., Norris K. 1996. The importance of carotenoids in signaling during aggressive interactions between male firemouth cichlids (Cichlasoma meeki). Behavioral Ecology 7, 1-6

Kodric-Brown A. 1985. Female preference and sexual selection for male coloration in the guppy (Poecilia reticulata). Behavioral Ecology and Sociobiology 17, 199-205

Kodric-Brown A. 1998. Sexual dichromatism and temporary color changes in the reproduction of fishes. American Zoologist 38, 70-81

Rowe M.P., Baube C.L., Loew E.R., Phillips J.B. 2004. Optimal mechanisms fo finding and selecting mates: how threespine stickleback (Gaserosteus aculeatus) should incode male throat colors. Journal of Comparative Physiology A190, 241-256

Ruell E.W., Handelsman C.A., Hawkins C.L., Sofaer H.R., Ghalambor C.K., Angeloni L. 2013. Fear, food and sexual ornamentation: plasticity of colour development in Trinidadian guppies. Proceedings of the Royal Society, Biological Sciences 280, 20122019

Vorobyev M., Marshall J., Osorio D., Hempel de Ibarra N., Menzel R. 2001. Colourful objects through animal eyes. Colour Research & Applications 26, 214-217.