Black color occurs in coloration of many freshwater fish beening relatively constant throughout the year and cryptic (in such, for example, bottom dwelling fish as wels, Silurus glanis). In this paper, we will consider those frequent cases when chiefly males of freshwater fish acquire black coloration in the reproductive period (nuptial melanization).

For desalinated areas and rivers of the Ponto-Caspian basin, five species of gobiid fish with nuptial melanization of body are most typical and abundant. Round goby, Neogobius melanostomus, monkey goby, N. fluviatilis, ratan goby, N. ratan, black goby, Gobius niger, and racer goby, Mesogobius gymnotrachelus, are among them. Gobies are marine origin, but the foregoing species (as well as many amelanistic species) inhabit desalinated areas and readily migrate into rivers of the Ponto-Caspian basin where successfully breed (Pinchuk et al., 1985; Romanesku, 2012). Some other euhaline gobies develop black nuptial coloration, such as giant goby, Gobius cobitis), but they avoid oligohaline bays and fresh waters.

In the reproductive period, gobies acquire conspicuous black coloration practically of the whole body using such an appearance, on the one hand, to repel rivals (in this case, black coloration is called threat, or antaposematic) and, on the other hand, to attract females (Trifonov, 1955; Yankovsky, 1966). Some gobies acquire color rims on the edge of both dorsal fins, pair pectoral and anal fins: white in N. melanostomus, yellow in M. gymnotrachelus and orange in N. fluviatilis. In accordance with the accepted terminology (Trifonov, 1955; Yankovsky, 1966), these conspicuous color signs are called gamosematic, bacause these signs appear in males when they prepare the nests, indicating in this way on their readyness to breed, and disappear in males when they begin to protect the nests with laying eggs.

Spawning and nest guarding in N. melanostomus are well documented (Meunier et al., 2009).

In general, round goby, N. melanostomus, and other gobies are rather visually guided fish with the specialized chemoreceptory channel. N. melanostomus respond poorly to the odors of lake whitefish (Coregonus) tissues, crushed dreissenids and fish eggs (Sreedharan et al., 2009; Yavno & Corkum, 2011). At least Sreedharan et al. (2009) do not recommend to use food-baited traps to control the spread of these fish. According to Rollo et al. (2007), N. melanostomus have well developed vocalization and are attracted by conspecific calls in both laboratory and field trials.

Nuptial melanization is also found in such fish of the North American ichthyofauna as dirty darter, Etheostoma olivaceum, Gila topminnow, Poeciliopsis occidentalis, and Olympic mudminnow, Novumbra hubsi (Kodric-Brown, 1998). Coloration of males in brook stickleback, Culaea inconstans (Ward & McLennan, 2006), mosquitofish, Gambusia holbrooki (Horth, 2004) and Amur sleeper, Percottus glehni (Tsepkin, 1977), are other examples of nuptial melanization.

Interestingly, in mosquitofish, G. holbrooki, black males have advantages and disadvantages to more common silver rivals. On the one hand, largemouth bass, Micropterus salmoides, crayfish (Procambarus) and dragonfly larvae (Libellulidae) prefer, as natural predators, silver males (Horth, 2004), that is black males are under less predation pressure. According to Taylor et al. (1996), on the other hand, females of G. holbrooki prefer silver males and even can avoid black males.

Basic References

Horth L. 2004. Predation and the persistence of melanic male mosquitofish (Gambusia holbrooki). Journal of Evolutionary Biology 17, 672-675

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

Meunier B., Yavno S., Ahmed S., Corkum L.D. 2009. First documentation of spawning and nest guarding in the laboratory by the invasive fish, the round goby (Neogobius melanostomus). Journal of Great Lakes Research 35, 608-612

Pinchuk V.I., Smirnov A.I., Koval N.V., Shevchenko G.G. 1985. On the present distribution of gobiid fish (Gobiidae, Pisces) in the Dnieper river. Hydrobiological research of fresh waters. Naukova Dumka Publishers, Kyiv, 121-130

Rollo A., Andraso G., Janssen J., Higgs D. 2007. Attraction and localization of round goby (Neogobius melanostomus) to conspecific calls. Behaviour 144, 1-21

Romanesku V.K. 2012.  Gobies (Perciformes: Gobiidae) in water bodies of the Republic of Moldova. Modern problems of fisheries management and ecology of the Azov-Black Sea region.VII International Conference: June 2012. Kerch, Ukraine, 171-174

Sreedharan G., Corkum L.D., Johnson T.B. 2009. Response of the round goby, an invasive fish, to food odours. Verhandlungen des Internationalen Verein Limnologie 30, 1275-1278

Taylor S.A., Burt E., Hammond G., Relyea K. 1996. Female mosquitofish (Gambusia affinis holbrooki) prefer normally pigmented males to melanistic males. Journal of Comparative Psychology 110, 260-266

Trifonov G.P. 1955. Breeding biology of Azov gobies. Proceedings of the Karadag Biological Station 13, 5-46

Tsepkin E.A.1977. On the nuptial dress of male Percottus glehni Dyb. Ichthyological Journal 17, 945-947

Ward J.L., McLennan D.A. 2006. Changes in agonistic, courtship and parental displays of the male brook stickleback, Culaea inconstans, across the breeding cycle. Behaviour 143, 33-56

Yankovsky B.A. 1966. On the breeding biology of some Azov gobies (Gobiidae). Hydrobiological Journal 2, 48-52

Yavno S., Corkum L.D. 2011. Round goby Neogobius melanostomus attraction to conspecific and heterospecific egg odours. Journal of Fish Biology 78, 1944-1953