As someone who doesn't keep bass but keeps lots of Geos (Satanaperca) and other HITH-prone fish, my experience is that stress, water quality, water characteristics and species propensity are the most significant factors.
Filtration and water quality are, of course, quite different. I've seen lots of heavily-filtered tanks with poor water quality from inadequate water changes, failure to clean canister filters regularly, dirty sumps, etc. Less waste = less nitrates = better water quality.
I don't think water quality alone is the answer, though. Especially for fish from blackwater, I think that water characteristics that mimic their natural environment matter. Driftwood, peat, etc. produce natural turpines and other chemicals that some fish need. I've actually depleted these in tanks by doing too many water changes. And the fish suffered.
Living in captivity - no matter how big the tank - can be stressful, especially for wild fish. Some species get stressed out in community settings or as a result of crowding. In my experience, this results in HITH.
Some species - especially those from blackwater conditions - are especially susceptible to HITH. They just are. When I keep these species, I know that I need to be on the top of my game with regard to the issues above - can't miss water changes, need to use peat and almond leaves in the tank, clean the filters, etc.
The article linked above lists red wiggler worms as a great source of nutrition and minerals. I've cultured them for years and they seem like an ideal food for bass. They are for other cichlids.
Good thread!
Matt
