Fishguy2727
12-31-2007, 02:01 PM
Hole in the Head (HITH) and Head and Lateral Line Erosion (HLLE) in freshwater fish are two complex issues with a lot of debate over the causes and cures for each. I differentiate between the two in that HITH involves parasites (Hexamita spp. and Spironucleus vortens) whereas HLLE do not. Even if lateral line erosion is not present I still classify those cases as HLLE. I really started to take a close look into these conditions when my 15” jaguar cichlid came down with HLLE. As I researched I came upon a lot of resources and it seemed like every one of them thought they were an, or rather THE, expert, the others were all wrong, and every opinion was different. So I went through as much information on the subject as I could find, talked to as many people about it as I could, and checked all the books I have or came across in bookstores. I did my best to absorb it all, comparing them all as I gathered more information. I tried to find the inconsistencies and the trends that seemed to be true of all the experiences.
A lot of strong trends developed. Many of the theories were supported by numerous cases. However, not all of these cases agreed with each other. The cases discussed are from people and cases online, cases from books, or people I have spoken to unless they are described as my personal experience. I have been careful to avoid taking what has been shown to be causes in marine HLLE and applying those to freshwater because you simply cannot assume it is the same thing.
HITH:
Many people do not believe any pathogens are involved with HITH or at least only secondary infections, not a sole cause of HITH. However, I have had a single case and heard of a number of other cases that show that metronidazole alone can cure a case of HITH.
My personal case involves discus. Not long after I got my school of discus a couple of them came down with HITH. They had narrow, deep pits with white discharge. One actually had so much discharge you could not see the hole, just the white discharge. They were in a 55 and I moved them into a 20 high. The diet was not changed, they were kept on just New Life Spectrum Thera+A. The water changes stayed the same (about 80% every week). The only difference was that I treated them with Aquarium Solutions’ Metro+, a metronidazole medication. Within a few days I saw improvement. The holes were getting smaller and the discharge was being reduced. At about this time you could see the hole that had been under all that discharge. Within a week the HITH was just about gone, with just a little healing left to finish. Now there is no scarring or any marks showing what had happened. In addition after they were cured things were not changed. They are still on New Life Spectrum, still on a weekly 80% water change. The only change I have changed is that I no longer use a buffer to keep the pH at 6.5, and they were very recently moved to a planted tank (which holds at about 7.0). If the diet and water quality is the same before and after the HITH but HITH has not occurred since the first time, then obviously the diet and water quality are not to blame in this case. What changed was the use of metronidazole, which wiped out whatever pathogen was causing the HITH (Hexamita spp. or Spironucleus vortens). If this was not the case then HITH would have almost certainly occurred again.
In tests it has been shown that Hexamita spp. and Spironucleus vortens were present in cases of HITH. These pathogens are susceptible to metronidazole. This further supports that HITH is caused by these pathogens.
I have heard of other cases where metronidazole was the only change and it cured the HITH. In even more cases it is part of the treatment, but obviously these do not necessarily support that parasites are involved.
Some theorize that small parasites make their way into capillaries causing these capillaries to be blocked, leading to the tissues past the blockage to become either necrotic or simply less supported by the bloodstream, leading to the deterioration of that tissue. Since nerves require a rich blood supply there are more capillaries around nerve dense areas, such as the lateral lines and sensors on the head. This nerve tissue may also be more sensitive to the effects of such blockages, causing them to be the first place to display the symptoms.
It is also theorized that poor water quality and/or diet stress the fish and allow these parasites (already present in the gut, but in a more subdued condition) to take hold. As they take a stronger hold they could be taking more of what nutrients the fish is getting, amplifying the stress of a poor diet. Then other issues discussed later in the HLLE section come into effect.
In my experience there are two requirements for illness in fish. First of all the pathogen needs to be present. For example, if there is no Ichthyophthirius multifiliis in the tank then the fish will not get ick. Secondly, the fish need to be stressed. This can come in MANY forms. Temperature, pH, other water parameters, water quality, aggressive tank mates, poor diet, and many other things can all cause stress in fish. This stress weakens the immune system and allows whatever pathogens are present a chance to get started in the fish. In many cases removing these stressors can help strengthen the fish’s immune system enough that it can fight off the pathogen by itself, without the assistance of chemicals, medications, or other treatments (temperature, salt, etc.). Because of this I do believe that some cases that do not require metronidazole to be cured may actually have involved parasites, but by treating the initial causes of stress the fish was able to recover enough to fight them off on their own.
HLLE:
HLLE (cases not involving parasites as a cause) seems to be much more complicated with numerous causes. Because of this it seems to me that like Dropsy, HLLE is a symptom that can be caused by a number of factors, not a single distinct disease.
My 15” jaguar cichlid developed HLLE and I tried metronidazole to treat it but there was no effect. Many other cases have been attempted to be cured with metronidazole with absolutely no effect. This shows that there is more than just parasite induced HITH.
Water quality has been shown to be one of if not the most significant stressor in fish. In many cases of HLLE all that is needed is an improvement in water quality. In other cases an improvement in water quality and diet together prove to be all that is needed to cure HLLE. I have not seen anything describing the specific way in which low water quality (usually in the form of high nitrates and other harmful chemicals) actually causes the pits to develop. It may be that they stress the fish and/or its organ systems and physiology and this can end up causing physiological dysfunctions that could result in sensitive tissues (such as nerve tissues and their surrounding and supporting tissue) being affected first, then spreading to other tissues. This would reflect the progression of HLLE as starting out at the Lateral line and/or facial sensors then spreading to surrounding tissues, sometimes resulting in more hole than head and a severely eroded lateral line system.
A lot of strong trends developed. Many of the theories were supported by numerous cases. However, not all of these cases agreed with each other. The cases discussed are from people and cases online, cases from books, or people I have spoken to unless they are described as my personal experience. I have been careful to avoid taking what has been shown to be causes in marine HLLE and applying those to freshwater because you simply cannot assume it is the same thing.
HITH:
Many people do not believe any pathogens are involved with HITH or at least only secondary infections, not a sole cause of HITH. However, I have had a single case and heard of a number of other cases that show that metronidazole alone can cure a case of HITH.
My personal case involves discus. Not long after I got my school of discus a couple of them came down with HITH. They had narrow, deep pits with white discharge. One actually had so much discharge you could not see the hole, just the white discharge. They were in a 55 and I moved them into a 20 high. The diet was not changed, they were kept on just New Life Spectrum Thera+A. The water changes stayed the same (about 80% every week). The only difference was that I treated them with Aquarium Solutions’ Metro+, a metronidazole medication. Within a few days I saw improvement. The holes were getting smaller and the discharge was being reduced. At about this time you could see the hole that had been under all that discharge. Within a week the HITH was just about gone, with just a little healing left to finish. Now there is no scarring or any marks showing what had happened. In addition after they were cured things were not changed. They are still on New Life Spectrum, still on a weekly 80% water change. The only change I have changed is that I no longer use a buffer to keep the pH at 6.5, and they were very recently moved to a planted tank (which holds at about 7.0). If the diet and water quality is the same before and after the HITH but HITH has not occurred since the first time, then obviously the diet and water quality are not to blame in this case. What changed was the use of metronidazole, which wiped out whatever pathogen was causing the HITH (Hexamita spp. or Spironucleus vortens). If this was not the case then HITH would have almost certainly occurred again.
In tests it has been shown that Hexamita spp. and Spironucleus vortens were present in cases of HITH. These pathogens are susceptible to metronidazole. This further supports that HITH is caused by these pathogens.
I have heard of other cases where metronidazole was the only change and it cured the HITH. In even more cases it is part of the treatment, but obviously these do not necessarily support that parasites are involved.
Some theorize that small parasites make their way into capillaries causing these capillaries to be blocked, leading to the tissues past the blockage to become either necrotic or simply less supported by the bloodstream, leading to the deterioration of that tissue. Since nerves require a rich blood supply there are more capillaries around nerve dense areas, such as the lateral lines and sensors on the head. This nerve tissue may also be more sensitive to the effects of such blockages, causing them to be the first place to display the symptoms.
It is also theorized that poor water quality and/or diet stress the fish and allow these parasites (already present in the gut, but in a more subdued condition) to take hold. As they take a stronger hold they could be taking more of what nutrients the fish is getting, amplifying the stress of a poor diet. Then other issues discussed later in the HLLE section come into effect.
In my experience there are two requirements for illness in fish. First of all the pathogen needs to be present. For example, if there is no Ichthyophthirius multifiliis in the tank then the fish will not get ick. Secondly, the fish need to be stressed. This can come in MANY forms. Temperature, pH, other water parameters, water quality, aggressive tank mates, poor diet, and many other things can all cause stress in fish. This stress weakens the immune system and allows whatever pathogens are present a chance to get started in the fish. In many cases removing these stressors can help strengthen the fish’s immune system enough that it can fight off the pathogen by itself, without the assistance of chemicals, medications, or other treatments (temperature, salt, etc.). Because of this I do believe that some cases that do not require metronidazole to be cured may actually have involved parasites, but by treating the initial causes of stress the fish was able to recover enough to fight them off on their own.
HLLE:
HLLE (cases not involving parasites as a cause) seems to be much more complicated with numerous causes. Because of this it seems to me that like Dropsy, HLLE is a symptom that can be caused by a number of factors, not a single distinct disease.
My 15” jaguar cichlid developed HLLE and I tried metronidazole to treat it but there was no effect. Many other cases have been attempted to be cured with metronidazole with absolutely no effect. This shows that there is more than just parasite induced HITH.
Water quality has been shown to be one of if not the most significant stressor in fish. In many cases of HLLE all that is needed is an improvement in water quality. In other cases an improvement in water quality and diet together prove to be all that is needed to cure HLLE. I have not seen anything describing the specific way in which low water quality (usually in the form of high nitrates and other harmful chemicals) actually causes the pits to develop. It may be that they stress the fish and/or its organ systems and physiology and this can end up causing physiological dysfunctions that could result in sensitive tissues (such as nerve tissues and their surrounding and supporting tissue) being affected first, then spreading to other tissues. This would reflect the progression of HLLE as starting out at the Lateral line and/or facial sensors then spreading to surrounding tissues, sometimes resulting in more hole than head and a severely eroded lateral line system.