HITH is a disease complex which is poorly understood considering its considerable involvement in the hobby. the flagellate protozoan 'Hexamita' or 'Octomitus' is usually involved but not always.
the disease typically exists as a low-level infection in the intestines of a variety of coldwater fish and some cichlids .. notably oscars, discus and angels. in themselves, the "pits" that develop are not harmful when shallow and seem to come and go depending on the water quality.
if the parasites multiply and infestation persists, the errosions may become worse and internal organs become involved. treatment with metronidazole or dimetridazole has proven at least partially effective in treatment of the parasites and thus, the holes observed along the lateral line. 400 mg/10 gallons at 93F for 5 consecutive days with 30% water change prior to each dosing is the current most effective recommendation.
internal bacterial infections are often co-involved and should be concurrently treated with medicated food containing a broad spectrum antibiotic. if the fish are no longer feeding, this treatment is of course not possible and makes complete recovery very difficult.
diet is also suspect in this disease complex .. lack of vitamin C primarily. water quality has a significant impact on recovery -- even insignificant concentrations of ammonia or nitrite result in poor recovery. nitrates should be held below 10 ppm. increasing the variety of vegetable fibre in the diet concurrent with higher levels of vitamins including C and B12 are helpful.
stress from tanks which are too small, overcrowding, use of feeder fish and poor nutrition are implicated. while little scientific evidence exists for this theory, removal of carbon from the filter may help since some researchers suspect it of removal of trace elements from the water which exacerbates the problem.
some cichlosomas like oscars, the geophagines and acarichthys etc. will sometimes develop HITH if kept in hard alkaline water.
stray electrical current. if your fish mysteriously come down with HITH and your care is impeccable, or if your fish have a chronic problems with HITH generation after generation you might want to get a Voltmeter/Multitester. this device measures electrical currents. place one of the probes directly into the tank water, and ground the other. the dial should read zero(0). any reading over zero(0) and this could be your problem. fish are very sensitive to water conditions and electricity in the water is a major source of stress.
buy a grounding probe and install it in your tank, then try and determine which piece of equipment is causing the leak and either replace or discard it (heaters and power heads are common problem items), also follow the steps listed above in the cure section to insure you are covering all possible causes, unless you want to try and verify that this was the only factor.
a varied quality diet will go a long way to improving your fishes health, and prevention of HITH, but it probably wont cure it. To do this, you need to add a vitamin supplement to their food. note that an additional treatment which includes vitamin supplementation may prove useful. there are several vitamin supplements available on the market that you dose to the tank. stay away from these. vitamins are very unstable in water. they break down and dissipate quite rapidly. also, fish do not absorb vitamins to any great degree through their skin or gills.
given this, you have to dose the fish’s food. this is best accomplished using pellets. use liquid vitamin supplements that you can get at health food stores. these supplements have a very hi dosage, which is good considering their instability in water. use a multivitamin or vitamins B, C and D if you cant find the multivitamin. place the pellets in a bowl and use just enough of the supplements to cover the pellets. allow them to soak until they are slightly mushy but still firm. then feed. feed this every day. for picky fish that refuse to eat prepared foods, dose black worms with the vitamins, and allow them to sit for 24 hours. this kills some of the worms, but this isn't a problem. then freeze them. if you can not find the liquid supplements, you can use any regular multivitamins. you will need a mortar and pestle to grind them into a very fine powder. dissolve into a small amount of water, then soak the food in that.
