Hole-in-the-Head Syndrome (HITH), also known as Freshwater Head and Lateral Line Erosion (FHLLE), is an important syndrome which affects primarily gouramis, angelfish, discus, oscars and large South American cichlids. HITH can also occur in saltwater fish and is known as Marine Hole-in-the-Head Syndrome and also as Marine Head and Lateral Line Erosion (MHLLE). HITH lesions are most prevalent on the fish’s head, though they may appear on the fish’s flanks, following the lateral lines down the body. Fish with lesions can behave normally for quite a long time, but eventually they will become sluggish, lose their appetite and become hollow bellied.
An oscar has spots on its’ head called sensory pits, which are a series of fluid filled sacs with tiny hairs that sense vibrations and convert them to electrical impulses. Both the sensory pits and the lateral lines are responsible for a fish’s positional sense in the water. The sensory pits look like little pin holes, generally arranged in a cluster.

In Hole-in-the-Head disease, these sensory pits become erroded and there can be loss of the normal coloration (depigmentation) of the skin.

Sometimes, these ulcerated lesions expand and coelesce together, forming larger crater-type lesions. They can extend deeper into the muscle and even down to the skull. These open lesions may become secondarily infected with bacteria or fungi and such secondary bacterial infections may infect the bloodstream (aka sepsis), resulting in death.

There is still a lot of controversy about what causes HITH, but the most recent theories include a lack of minerals and vitamins from poor nutrition, specifically a lack of calcium, phosphorus and Vitamins C and D; and stress from poor water quality, especially high levels of nitrates (> 40 ppm), caused by overcrowding, insufficient filtration and/or poor tank maintenance. HITH occurs more frequently in larger, old fish, so it may be related to the diminished immune system that results when a fish ages.
One odd theory is that carbon usage causes HITH but this association is anecdotal among aquarists and has failed to be reproduced in studies.
One older theory is that HITH is caused by malabsorption of minerals and vitamins from the intestine due to heavy concentrations of flagellate parasites, like Hexamita or Spironucleus. It was once believed by aquarists that the protozoal parasite Hexamita caused the skin erosions and therefore treatment over the years was centered around attempting to eradicate Hexamita by treatment with metronidazole. There is still a strong belief that Hexamita may at times be acting as secondary infectious agent, inhibiting wound healing. However, there is no proof that Hexamita is even present in most lesions.
Treatment of HITH is aimed at improving poor nutrition and/or poor water conditions!
One must always keep a close eye on the quality of the water by testing the water parameters. The pH should remain stable and the ammonia and nitrite should read zero and the nitrates should be less than 20 ppm, with 10 pmm or less being ideal. The tank must have adequate filtration, and regular tank maintenance with partial water changes, in order to keep these levels in check. If your tank is too small or overstocked, it will be nearly impossible to keep nitrates below 20 ppm. This can be remedied by upgrading your tank size, by reducing the amount of fish in the current tank, avoiding overfeeding and/or by increasing the frequency of partial water changes.
Feed your oscar a varied diet of pelleted food that contains supplemental vitamins (e.g. HBH Oscar Show). You can also choose a pelleted food that will provide a good staple, such as Hikari’s Staple, Gold, Biogold, New Life Spectrum or Omega One and supplement it with vitamins. You can add the vitamins yourself. Put pellets in a single layer in a small glass jar and pour in enough liquid multi-vitamin (human multi-vitamins are fine to use) to cover the top of the pellets and let them soak for about a minute or until they are soft, but not mushy or falling apart, and then feed. Vitamin supplemented pellets can be fed 2-3 times per week as a preventive measure but can be fed daily when treating HITH.
Additionally, supplement your oscar’s diet with crickets, mealworms, blackworms, earthworms and shrimp but avoid spiders and other poisonous/stinging insects and anything that could have come into contact with pesticides. Oscars are insectivores and should not be fed feeder fish because they provide little nutritional value and an oscar will have difficulty digesting the scales of some feeder fish. Also, many aquatic animal tissues contain thiaminase, which when fed raw to fish can lead to a thiamine (Vitamin B12) deficiency. As well, feeder fish are often kept in extremely poor conditions, so they may introduce disease into your tank.
It is advisable to culture HITH lesions and treat with an antibiotic that the bacterium is susceptible to because this has been shown to aid in healing. Unfortunately, most aquarists do not have the ability to culture and identify bacteria. So, as a final treatment option, aquarists continue to use medications containing metronidazole as a bath (e.g. Hex-a-Mit), in order to treat a secondary infection from Hexamita that might be preventing healing. Metronidazole also treats Spironucleus as well as various other bacteria, so it may be of benefit on that basis. If unable to find Hex-a-Mit or Seachem’s powdered metronidazole, then metronidazole tablets from your vet or physician can be used. Metronidazole is used at a concentration of 5 ppm and this can be achieved by using a 250 mg tablet for every 50 liters (or every 13 gallons) of aquarium water. The tablet(s) are crushed and dissolved first in lukewarm water, then added evenly over the water’s surface. After three days, change one third of the water and add fresh carbon to your filter to remove the drug. This drug may be harmful to sensitive plants but should not harm the bio filter. For aquarists in other parts of the world, who are unable to find Hex-a-Mit, they may use Waterlife’s Octozin.
The following documents the efforts that Chelle took in order to fight this disease in her oscar, Charlie.
Specs on Charlie’s tank:
Tank Size 75 gallon
Filtration Cascade 1200 canister filter 315 gph=4x turnover per hour
Tankmates Two oscars- 8″ & 9″ Two plecos- 6″ & 7″
Diet Tetra Cichlid Sticks, Hikari Gold, Hikari Staple and Wardley Cichlid Pellets.
As treats- earthworms, triops and frozen salad shrimp.
pH 7.8 Ammonia 0 Nitrite 0 Nitrate <10 ppm

Treatment then consisted of feeding pellets, which contain vitamins, daily. Chelle used HBH Oscar Show, which contains Vitamin A, B1, B2, B6, B12, C, D3, E, K3, Biotin, Choline, Folic Acid, Niacin, Pantothenic Acid, Manganese, Potassium, Zinc and Selenium. Concurrently, a course of metronidazole was added to the water. After two weeks, the lesion begins to heal as noted by the base and edges of the lesion, which are beginning to contract.

The metronidazole was discontinued, Melafix was resumed and the vitamins were continued. Unfortunately, the healing of the HITH lesion cannot with any certainty be attributed to treatment specifically with either metronidazole, Melafix (tea tree oil) or vitamins.

All treatment was stopped except the vitamin supplement. Two weeks later, the HITH lesion had healed completely!

Chelle’s keen eye recognized early on, an HITH lesion on her oscar, Charlie. Early diagnosis of HITH leads to early treatment, which can then lead to a cure! Treatment is simple and effective. Maintaining excellent water quality with frequent partial water changes to keep nitrates under control and feeding a varied diet, supplemented with vitamins, are simple measures, which both treat and prevent Hole-in-the-Head!
If you need help with your fish with Hole-in-the-Head, just ask for assistance in Flippers ‘n’ Fins’ Cichlid forum!

References:
Fish Disease: Diagnosis and Treatment: Dr. Edward J. Noga, Iowa State University Press, 2000.
Fish Medicine: Dr. Michael Stoskopf, W.B. Saunders Company, 1993.
Handbook of Fish Diseases: Dr. Dieter Untergasser, T.F.H. Publications, Inc., 1989.
The Manual of Fish Health: Dr. Chris Andrews, Adrian Exell & Dr. Neville Carrington, Tetra Press, 1988.
A special thanks to RedOscar12, who is the site owner and administrator of FishAdviceForum.com, for allowing us to use his pictures of advanced HITH. May your oscars R.I.P.
Author: Chelle & Dr. Barb