Number one cure (
IMHO)
(1)
Get your water quality/chemistry perfect,
NH3-0,
NO2-0,
NO3- 0/20ppm,
check your filters & clean'em if necessary (reduces alot of
NO3), gravel vac &
PWC, do small
PWC's (10%) every other day.
Just about everyone will agree that bad water chemistry and HITH go together like apple pie -n- ice cream...
(2)
Add liquid vitamin supplements to all food and vary their diet.
Soak or load everything you feed the fish with vitamins until cured and watch your water.
Vitamins that you add to your tanks water are worthless (
IMO).
We use "Vita Chem", our fish get it regularly.
This particular brand is available at most on-line retailers and at better
LFS's (We get ours at BigAls).
http://www.bigalsonline.com/catalog/product.xml?product_id=27489;category_id=3781;pcid1=2911;pcid2=
(3) Supplementary treatment.
I would add a dose of salt to the tank, this helps lower stress, encourages slime-coat production and gill function amongst other things.
Also a dose of Melafix and Pimafix, these have been known to help healing.
(4)Medicate,
Alot of folks blame Hexamita for HITH and thus treat for it with medications, BUT, studies have been done showing that Hex (and others) is/are a secondary infection/s (Whether or not Hexamita plays a key-role with HITH infections is controversial).
You need to do what "You" feel is right and correct after reseaching this for yourself, google "HITH causes prevention and cure" or some such, and visit Cichlid specific forums for more info.
Some folks also think that filter carbon plays a role with HITH...
It seems there are no absolutes as to the cause, but just like ICH there are many ways to treat it and proponenets/opponents of each treatment.
Steps (1) & (2) are how I try to prevent HITH, and would treat a early case of HITH. I would proceed further if I wasn't able to control/cure with those.
I say again though...
Perfect water quality and a varied nutritious diet supplemented with vitamins.
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Here's a good article on HITH from another favorite fish site of mine,
http://www.oscarfish.com/cms_view_article.php?aid=3
Lots of talk about HITH there, symptoms, pics, treatments and preventative measures. There are some current threads on HITH and plenty in the search engine. The Advisors over there know their Oscars.