The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.
HITH is a parasitic disease found in angelfish and discus. It is caused by Hexamita spp. and/or Sprionucleus vortens and is treated with metronidazole and praziquantal.
HLLE is a nonparasitic condition usually caused by less than ideal food and water quality. This is common in oscars (and many other species). It does NOT respond to any meds, but is treated by improving food and water quality. In some very rare cases it has been demonstrated that the cause in those cases was carbon use in the filter.
Oscars and other larger new world cichlids rarely get HITH, they get HLLE. They key to prevention and or curing is keeping the nitrate concentration below 20ppm(10ppm is better) and feeding a high quality and easily digestible pellet such as New Life Spectrum. Depending on how severe the deterioration of the sensory pits is there may be some permanent scarring but follow the above directions and there will be improvement.