The Hole-In-The-Head/Lateral line erosion FAQ
Nathan Henderson  

DISCLAIMER: Although I have tried to cover the subject thoroughly and accurately, my resources are limited, and mistakes do happen. As such, any and all feedback, criticisms, suggested additions or changes, additional references or suggested lines of inquiry, etc. are greatly appreciated. This is very much a work in progress. Send info/flames/etc to:

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  1. What is Hole-in-the-head/head and lateral line erosion?
  2. Is HLLE dangerous to my fish?
  3. What causes HLLE?
  4. How do I treat HITH/HLLE?


Q: What is Hole-in-the-head/head and lateral line erosion?

A: Hole-in-the-head (HITH) and Head and Lateral Line Erosion (HLLE) are two terms for the same problem--skin de-pigmentation and the formation of holes, ranging from pin-hole sized to large craters, in the head and along the lateral line of fish. A small 'hole' in the head doesn't always mean HLLE though--the fish most commonly affected have small pores in their face area naturally--if you aren't sure, compare the size and location of the 'hole' to other fish. If it's the same on all fish or on both sides of the fish's head, it's probably nothing to worry about, but even this can be difficult to judge since the holes often appear in the same locations on different affected fish. As such, a good familiarity with your fish and/or a good picture of a healthy fish can be valuable for diagnosis. Freshwater HLLE is most commonly found in the larger South American cichlids, particularly discus, oscars, and Geophagus species.

Q: Is HLLE dangerous to my fish?

A: HLLE is a chronic disease, meaning that it's presence is not fatal in the short term. However, affected fish can eventually become anorexic and lethargic, and the open wounds can easily become the source of secondary bacterial and fungal infections. (1) E. Noga speculates that these secondary infections may be the ultimate cause of death in fish with HLLE. Although it is not normally immediately fatal, HLLE should be treated as soon as possible, both for the fish's health and to prevent permenant disfigurement of your pet fish. (Small holes at least can heal fairly quickly, but very large holes may take months to heal or never heal completely at all.)

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