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Pet Product News Editorial Blog:

Friday, March 5, 2010

Hole in the Head

By Patrick Donston

Store Owner, Absolutely Fish


A fish disease that's always fascinated me has been "Hole in the Head," also referred to as HLLD (head and lateral line disease). One reason, is it's easy to diagnose, yet challenging to cure. I've read many articles, fish disease books and scientific journals on the subject. There are a variety of opinions, with some coming to no conclusion as to prevention or treatment. It is also one of the few fish diseases that actually can be diagnosed in ornamental freshwater as well as marine fishes.

Diagnosis is the same in 2freshwater and marine fishes. Small tubular holes appear on the head and lateral lines of the body. The holes will increase in size over time, actually appearing as if the skin is "chipping" away on the fish. Fishes in chronic phases may appear to have developed craters or severe discoloration over the head, progressing down the lateral line of the body. The disease can leave a fish with a horrific appearance, yet fascinatingly, it behaves normally--eating and swimming about.

Another interesting occurrence of the disease is that it seems to affect specific types, but not all fishes in marine and freshwater aquariums. Marine fishes from the families Pomacanthidae (angelfish), Acanthuridae (tangs or surgeons), Chaetodontidae (butterflys) and Seranidae (groupers) seem to show diagnostic symptoms more often than other types of marine fishes. Freshwater species from the cichlid and gourami families are most prone.

While the underlying cause of the disease remains unclear, there are notable speculations and minor success in treatments. It has been documented in freshwater cichlids, discus and angelfish that a flagellate protozoan (Hexamita or Spironucleus) is the root of the problem.

These protozoa probably live within the intestines and guts of these fishes most of their lives and do little harm. When fish are exposed to poor water quality, diets, overcrowding, or unsanitary conditions, the immune system becomes suppressed, leaving the protozoa to multiply and develop acute symptoms.

Increasing filtration, oxygen, UV sterilization and water changes should help. It is also recommended to feed medicated foods designed to kill and clear the gut of protozoa. Medicated pellets with metronidizole, praziquantel, piperzine citrate or quinine hydrochloride work best when soaked in garlic or vitamin C.

In marine fishes, a variety of environmental stressors has been hypothesized:

  • High nitrate levels from lack of water changes;
  • Stray voltage from pumps and heaters in aquariums not properly grounded with a ground probe;
  • High bacterial or viral counts from under UV sterilization or protein skimming;
  • Poor diets (lack of vitamin C);
  • Lack of p roper lighting--proper lighting helps fishes produce vitamin B in the epithelial cells of the skin;
  • Low oxygen levels and under filtration; and
  • Overexposure to copper medications.

Correcting any or all of these problems may help. You should also consider a high vitamin C-induced diet. It has also been documented that antibiotics such as nitro-furazone will help clean the fish of secondary bacterial infections, which may be affecting the epithelial cells of infected fishes.

I find the disease challenging because, as much as I've researched, there are no clear causes or cures. I can tell you we have little to no problems with the disease in our shop or even in our client's aquariums. Our secret is always: "Great water, good nutrition."

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