When you do only minimal water changes, the build up of a buildup of nutrients, in combination with a high pH is what encourages HITH.
I try to do 30% to 40% every other day, and have been doing this routine for over 20 years, and have not seen HITH since,.
Before I started this rigid routine, the soft water fish I tried would occasional ly get infections as time passed.
I have seen medications advised, but they do not get to the root of the problem, and since HITH is chronic, it does not happen over night.
It starts to show up just as large fish mature and you are expecting them to look their best (but it can show up sooner, the higher the pH and conductivity).
With oscars, it usually seem to start presenting at about 2 years of age.
The tannins from leaf litter, peat, or Reiboos tea have anti bacterial properties that help.
Because tannins are organic, the things that produce tannins, need to be replaced.
I experimented with almond leaves, because I wanted to see if the efficacy rumors were relevant.
There are at least 2 almond trees on the island where I live, and after todays 4 hour storm, I collected about a half dozen fallen leaves . These were dropped in my tank (180 gal with a nearly full 125 gal sump) still floating a couple hours later Initial pH was measured 3 times with 3 aliquots...
www.monsterfishkeepers.com
When in the states, I was experimenting with some soft water killifish, and found if I put enough leaf litter in the tanks to about 1/4 of the tanks volume, it helped
But in this case it was not to stop HITH (their life span was too short to get such a chronic disease)
It was to give the proper conditions to encourage breeding.
I also mixed low pH rain water into their small tanks, due to my high pH tap water.
I also find heavily planted tanks, or sumps help.
With cichlids planting their tanks can be problematic (especially with vegetarians like pearsei)
In cases like that. I plant the sumps that filter their tanks.
Below the sump, that filters my current Panamanian cichlid tank.
