i couldn't be hormones as if the hormones are too strong the fish cant even swim around. are they eating well? if they do i would suggest its a parasite. ive seen it in this website www.aquariumpharm.com. they do have that type of disease you called it the black spot. but i do think it is harmless. i do have some cichlids with this black spots it doesn't do a thing. for a week or two it'll go off. in that website it says there is no prolific cure of this disease. not too. well if your fishes "touch wood" doesn't die and healthy , dont bother bout it anyway. maybe you could try some anti parasite meds. i found that this med named coppersafe is good. its from some mela or something lab. good luck aight?