While dip-netting in a FL canal I came across one of the most interesting and beautiful fish in freshwater, the bluespotted sunfish, Enneacanthus glorious (see photo). This fish is well named since the adult males are covered with brilliant blue spots that shine intensely. It is a wide-spread species occurring in the coastal plain from Florida to New York, especially in heavily vegetated, slow-moving waters. Note that the tail-fin is rounded and not forked as in most sunfish; this may be an adaptation for a life in thick vegetation. This gorgeous fish is also unusually tolerant to low pH’s down to about 4.5, a very useful attribute for a fish living in dark, acidic waters.
The striking coloration of the male appears to be designed for attracting females and likely advertises the health and vigor of the male, in a way much like the mane of male lions. We have a fish (the mountain redbelly dace- see attached photo) in the creeks of our Blue Ridge mountain farm which has a similar characteristic, namely a very bright coloration of adult males. It is likely that the purpose of this “gaudy male syndrome” is similar wherever it occurs. One of the amusing aspects of this trait is that females get to choose the males, and are probably anxious to choose the best genetic stock to fertilize their eggs.
If this all seems strange to humans it is because we have a somewhat different mating system in which the male is not gaudy but is larger and stronger than the female and engages in male combat for territory and females. However this is not to say that the female does not make a choice of her mate!
The variety of color and form in Nature is remarkable and a continuous source of wonder, speculation and study.
Bill Dunson, Englewood, FL & Galax, VA