Hole in the Head Disease - Causes, preventions & treatments.

Hole in the Head Disease


Hole-in-the-head (HITH) disease also goes by the names head and lateral line erosion (HLLE) and lateral line depigmentation (LL) depending on the symptoms the fish show. It is most common in Cichlids such as discus, oscars, severums, and angelfish, but it can infect any freshwater fish. Try not to panic if your fish become infected, it is preventable and curable if you notice symptoms and treat it early on.


Primary & secondary causes

The cause of this disease is not entirely clear, no one knows the exact trigger for fish to catch this disease. It is thought it could be caused by a flagellate parasite called Hexamita which first infects the intestines and then spreads around the rest of the body.  The parasite is likely to already be in your fish’s intestines but at low levels. When the fish becomes weakened the parasite can multiply. It damages the lining of the fish’s gut therefore affecting the fish’s ability to digest food. Once the fish has developed the eroded holes around the head, sensory pores, and lateral line, it is in serious need of help.

The lateral line allows the fish to feel vibrations under the water. It also allows fish to avoid other fish and objects in the aquarium. When the fish’s body becomes pitted from the disease the lateral line is unable to function properly. This could lead to increased aggression from other fish as they are unable to sense them and cause injury to the fish if they bump into any objects in the aquarium.

If the disease continues, it causes the surrounding tissue to rot creating open lesions as an entry point that pathogens can enter and cause secondary infections.  

It is thought the parasite thrives well in an aquatic system where fish are overstocked, filtration is insufficient, and lack of water changes are happening. It is always important to carry out water changes often, as an increase in ammonia and nitrate levels may cause an outbreak in your aquarium.

It is also thought the disease comes from vitamin deficiencies which may be due to the use of activated carbon in closed aquarium systems. There is a direct link between the disease and nutrition deficiency in aquarium fish. Specifically, vitamin C deficiency in the diet encourages hole in the head to take over.

Unhealthy water conditions are also an attribute to a fish getting infected. Any changes in conditions are stressful for any fish in an aquarium, especially in older fish who are less tolerant to changes so making them more likely to get sick. Water may become acidic from activated carbon. Some hobbyists use activated carbon or charcoal as a filter media, however, this can contribute to HITH disease.


Signs and Symptoms


  • Pale, pitted holes/lesions around the head
  • Fish will become thin, weak, and have a bloated stomach
  • Lesions will also appear on the lateral line and flanks
  • Parasitic larvae can be seen hanging out of the holes
  • White, stringy faeces
  • Secondary bacterial and fungal infections will occur if left untreated



  • The fish may start acting lethargic
  • They may have trouble swimming due to difficulties balancing
  • Loss of appetite
  • Depression
  • Fatality



As mentioned above, it is important to treat this disease fast before further implications occur. If possible, always treat sick fish in a separate tank and quarantine them. As soon as you see any of the above signs and symptoms you must start the treatment for your fish immediately.

Firstly, use an antibiotic treatment called metronidazole, which can be added into the aquarium with the infected fish one time a day, for three days. It is recommended you mix ¼ tsp per 75 litres of water in the aquarium and combine with a 25% water change every 24 hours before you repeat each treatment. When using a medical treatment, you should separate the infected fish to only target them. Be sure to constantly check and control the water quality throughout the process to your fish’s needs. The water change removes any activated carbon, afterwards check the pH and water temperature is stable.

Secondly, you will want to treat any bacterial and fungal infections.

You can also improve their diet by feeding high-quality frozen or flake food rich in vitamin C and high content of meat. You can feed the fish with iodine enriched food as they may not consume vitamins directly.

You will not see results straight away. Like ourselves, fish also need time to heal, the ulcers should start healing a couple of days after antibiotic treatment.



As with any fish diseases, combatting any stress should be your top priority. Stress comes from many factors, not just parasites themselves. Always ensure you have the best water quality conditions in your aquarium, check equipment regularly and carry out any maintenance if needed. Never overcrowd your tank as this increases stress and aggression.

When keeping cichlids, discus or oscars, hole in the head disease is likely to occur. Be familiar with the signs and symptoms and be fast to treat them.

Always feed your fish with the best species-specific food so their immune system does not become suppressed. If the aquatic environment is maintained properly your fish should not encounter the disease again.

Super Fix can be purchased here online, it contains strong natural antimicrobial and anti-bacterial compounds. Super Fix contains anti-mutagenic, DNA protecting properties which improve the immune system, assists in self worming, reduces stress of display stock, and can reduce fish loss. It is made from locally sourced ingredients and is safe to use with a variety of aquatic fish such as cichlids, tropical fish, catfish, loaches, yabbies and shrimp plus it can assist fish with many other known aquatic diseases. Head on over to the shop or product info tab to check it out!

Thank you again for reading, we hope to see you again soon, take care!