Mhlle

[Luis A M]

Dear Steve,
I liked very much your article,which is very helpful for the global understanding of this mysterious condition.
Some few years ago,I visited the "Rain Forest Cafe"in Orlando,Fl.
These thematic restaurants display huge acrylic tanks with a nice selection of tropical marine fish.They are run with a central filtration system and they have professional staff in charge.They could be compared to a small public aquarium.
Nevertheless,I saw there many and very bad cases of MHLLE.It affected not only acanthurids but also pomacanthids and even pomacentrids.I was surprised at the extent of this condition under what looked like a well cared large system.Perhaps the level of lighting was rather low for such very tall tanks, a compromise with the dimly lit cafe environment.
But my surprise was even worse when I visited another "Rain Forest",this time at the Sawgrass Mall,in Weston,close to Ft.Lauderdale,Fl.The situation was exactly the same!.
I don´t know if this happened also in other "Rain Forests"or if the problem was solved since then,but checking all common factors between these two (or other)cafes could provide some clue about the causes of MHLLE.A fascinating detective story...

[Steven Pro]

There are two or three Rain Forest Cafe restaurants in and around Orlando and on my last trip there (about 4 years ago) we ate in all of them. All of their tanks and fishes suffered severe cases of MHLLE. It was a shame that such focal points were so unattractive to someone that notices such things.

[dizzy]

Hi Steve,
Great article. I too have noticed an unusually high percentage of fish a large public displays exhibiting mhhlle. I been on a many of the behind the scenes tours as well and have a good feeling for the filtration and husbandry techiques they employ. While I didn't see you mention it in your article I suspect ozone might also have some roll in causing mhlle. If not directly, it may be removing something from the water that helps to act as a preventitive. My gut feeling is that when it comes to marine fish keeping there may well be such a thing as water that is to clean. I would also add that certain species of marine angels are also quite susceptable to this malady. The koran angel you mentioned in the article is one and Pomacanthus imperator is another that is frequently afflicted.

As a 20-plus year retailer I have certainly seen my share of fish that have developed the symptoms and I doubt there was always a common cause. My point of posting is that I very rarely (dare I say never?) see the symptoms develop in my display tanks and I keep a lot of the fishes that commonly develop this problem. I don't usually run carbon, I don't use ozone, and I don't add vitamins to their food. I don't use Miracle Mud. I don't worry about keeping nitrates extremely low either. Sometimes I go quite awhile between water changes. In most of my tanks I have a lot of corals and several tangs. I think the algae that wants to grow in this type of tank is a good food source for the tangs, and may well be the secret to the prevention of mhhlle problems. I'm starting to achieve some pretty good longevity numbers with many of my tangs reaching nine years plus without problems. Here is a list of tangs I'm currently keeping without any signs of mhhlle: Paracanthurus hepatus x 3, Zebrasoma xanthurus x 2, Zebrasoma veliferum x 1, Zebrasoma flavescens x 2, Zebrasomarostatum x 1, Naso lituratus x 1, Naso vlamingi x 1, Ctenochaetus striatus x 1, Ctenochaetus tominiensis x 1, and Acanthurus leucosternon x 1. I feed New Life pellets, PE mysis, Marine Supreme, occasional live brine, and I give them some caulerpa from my refugium. I try to feed at least three times daily. My feeling is that the near pristine water quality that is needed to keep unwanted algae from growing in large public displays with fake coral decorations, may not be the best for keeping tangs, angels, and other algae grazing fish in peak condition. The quicker you can get tangs out of bare holding tanks and into reef style aquariums the less likely they will develop mhhlle problems IME.
Mitch Gibbs

[Steven Pro]

First off, good to chat with you again Mitch. I hope we can see each other at this year's IMAC or MACNA conferences.

And by the way, the revolving display at the Pittsburgh Zoo & PPG Aquarium (actually all the displays) is looking really nice. Maybe the next time I take the kids over, I will take some photos of that tank and email them to you. Although, the round tank is hard to photograph without seeing the flash.

Anyhow, back to your point, it is hard to try to narrow down exactly what causes MHLLE.
My feeling is that the near pristine water quality that is needed to keep unwanted algae from growing in large public displays with fake coral decorations, may not be the best for keeping tangs, angels, and other algae grazing fish in peak condition. From this same statement, I could also theorize that the water conditions are only partly responsible and that the lack of a natural food source (algae) is actually the real culprit. I do agree with you that in most instances I can recall seeing MHLLE it has been in sterile displays consisting of bleached skeletal or synthetic corals. It is rare that I see MHLLE develop in a nice reef display, but that also happens as well, which leaves me scratching my head wondering what the common factor(s) is.

[dizzy]

Steven,
I think there must be more than one thing that can trigger the problem. I agree the stray voltage explanation is a non-starter. I have also seen it develop at public aquariums that feed a very good diet. It certainly seems possible it could be initiated by keeping fish in copper to long. I guess it is also possible that it could, in some cases be a delayed reaction to exposure to sodium cyanide. I have noticed that it can come on quickly or sometimes slowly. BTW I always thought it was called HHLLE which stood for Hole in the Head, Lateral line /Erosion.

Another area that needs investigation is the causes of blindness in marine fish. Perhaps some of the causes are overlapping. I certainly believe copper is detrimental.

I'd like to see the photos of the zoo tank. I have a 300-gallon revolving tank here at the store that is really doing well.
Regards,
Mitch

[Steven Pro]

I agree that multiple causes might trigger MHLLE. My short list of contributing factors are diet, water quality, copper, and stress. I don't buy any of the contagions, lack of sunlight, or stray voltage theories. And, I don't have a strong opinion one way or the other regarding activated carbon.

I will see what I can do about photographing the zoo tank.

[twalzem]

FWIW - I had the opportunity to dive on a reef off of the small island of Wuvalu, 300 miles north of New Guinea in 1974. At that time I witnessed a large three spot damsel with the classic MHLLE symptoms around its eye and head. I recognized it from captive surgeon fish and angels I had kept with the same apparent physical symptoms. From my personal experience, I would question that, at least from outward visual appearances, this disease does not, in some form, occur in the wild. I really took notice at the time, since I had a large regal tang with the same symtoms. I did not expect to see similar appearances in the wild (most deficient or flawed fish don't seem to last long on the reef, although this ailment doesn't seem to adversely affect survival rates). This damsel, like the affected fish we have experienced, acted normally, and actively defended its territory. Since I witnessed this on a thriving, pristine reef, one would have to wonder if this was (or could be) a dietary or environmental issue. Of course, there might be numerous causes that create a similar end result.

[Steven Pro]

That is interesting. Although, it is hard to draw to many conclusions on this one incident. For example, it is possible that this fish was in a captive environment and was released by an aquarist/diver. It might be unlikely, but it is impossible to prove one way or the other.

What would really be noteworthy would be for someone monitoring a reef to see a change and a pattern develop. For instance, a healthy thriving reef with a history of being in good shape then a hotel or farm or some other man made thing comes into the area and soon afterward a change is noted. MHLLE begins to spread to the fish in the area, nuisance algae starts popping up, coral coverage drops, etc.

While I might have seemed to discount your report, others have mentioned similar things. I did asked Bob Fenner, another noted author and diver, if he had ever seen MHLLE in the wild. He seemed to recall seeing it before, but could not remember the exact circumstances and thought maybe localized pollution levels had something to do with it. So, it is not totally unheard of, but hard to say one way or the other why it is seen in those fishes. Either way, it does not seem to be a wide spread affliction which might point to these instances being caused by pollution or from released fishes.

[Luis A M]

Is MHLLE mostly found in herbivorous fishes?.If this is true it points strongly to the nutritional cause.You mentioned groupers,though.
The fish at RFC looked unstressed and happy among these fake coral structures.But yes,the water was crystal clear and corals and glasses spotless clean,not a trace of algae.

[Steven Pro]

Originally posted by Luis A M
Is MHLLE mostly found in herbivorous fishes?.If this is true it points strongly to the nutritional cause.You mentioned groupers,though. MHLLE does not afflict only herbivores as you mentioned groupers fairly often exhibit this condition.