The only thing I know about black eyes is. If the iris is black it's a symtom of fish tb.
[URL="http/www.fishyportal.com/cgi-bin/pub/diag?c=v&id=49"]http/www.fishyportal.com/cgi-bin/pub/diag?c=v&id=49[/URL]
Taken from the link.
Fish Tuberculosis
Latin name: Mycobacterium piscium
Other names:
Pathogen: bacteria
Symptoms: An autopsy reveals numerous nodules in the spleen, liver, kidney, heart, intestines, gills, muscles, sex glands, skin, eyes, and the skeleton. The nodules have a curdled consistency and are of brown or white color, Clamped fins, Fish are inert, Fish do swinging movements, Fish hide in secluded places, Fish move in violent rushes, Fish stop feeding, Fish swing on their side, Black discoloration of the iris, Black spots, Bloat, Bloated front part of belly, Brightening (lighting) of body colors, Bump, Fish growth slows down, Fish stop growing, Fraying of fins, Leukoma (spot on an eye), Loss of eyes, Overall body thinness, Popped eyes, Scale raising, Scale shedding, Separation of fin rays, Skin became transparent because of very enlarged belly, Small dark spots, Tail fin is down
Affected fish become sluggish, hide in the corners of the aquarium, swim with the caudal fin down, stop feeding, lie on one side on the gravel with the head and tail up. They show swaying movements, folded fins, emaciation, fading colors, eroding fin rays, bumps that turn into lesions, scale loss, ulcerous skin wounds, dark coloration of the iris, eye protrusion, and black spots all over the body. These symptoms may occur singly or in various combinations. If Tuberculosis is suspected, the liver and kidneys should be thoroughly examined. Through the magnifying glass and sometimes with the naked eye one can observe nodules of whitish to yellowish color. Microscopic examination will reveal pathogens. An autopsy will reveal numerous nodules in the spleen, liver, kidney, heart, intestines, gills, muscles, sex glands, skin, eyes, and the skeleton. These nodules have a curdy consistency and are of brown or white color. Examination of internal organs of Cichlids and Anabantidae will often reveal melanized tubercles (grainy black formations). They are from 60 to 200 micrometers in size. Later stages of mycobacteriosis are characterized by hardening and hyperplasia of thick connective tissue which fills in elements of affected areas (cirrhosis).