HLLE Related To Stray Voltage?
Ground probe 3/20/09
Hello crew and thanks for all the great advice.
<You're welcome.>
The question has been asked before regarding the value of a ground probe.
I am in agreement with the argument that the probe completes the circuit and the resulting flow of
current is a bigger problem from a fish and human safety perspective. I have a 125g FOWLR with powerheads and heaters in the main tank and the following fish: Powder Brown (A. japonicus), Tomini Tang, Flame Angel and an Assasi Triggerfish. The Powder Brown, Flame Angel and Assai are fine,
but the Tomini has what appears to be mild HLLE on his forehead and it has been very slowly increasing in size for the past 6 months. Also the behavior of the Tomini is more reclusive then active, color is good and
seems to only like to eat New Life Spectrum pellets along with grazing the rock and tank walls. I feed a varied diet ( New Life Spectrum various pellet formulas, Nori, Formula II, Mysis and supplement with Selcon). I decided to try the ground probe and I have noticed an immediate change in behavior. The Tomini is more active and less reclusive and now regularly eats Nori. The mild HLLE seems to be slowly improving, but its to early to be certain. The other fish have not changed their behavior. The equipment
in the tank is working fine and all are connected to GFIs. I plan to experiment some more to better confirm if the ground probe addition is the primary reason for the change in behavior. I also speculate that if the
ground probe is a benefit then maybe the Tomini is just more sensitive to very low electric fields relative to the other species in my tank. The question is has there been any new information on this topic that may help
clear up the controversy or is this still just a myth?
No myth, has been cited several times/places and your experience does not surprise me.
If you had any stray voltage/current in your tank it would be very low due to your GFIC protection. GFIC's will trip when a difference of 5 milliamps (.005 A) is detected. Simply said, if .25 amps are going out to the
component, .25 better be coming back or the GFI will trip. As to new info on HLLE, none that I'm aware of. Do some Googling, and thank you for sharing your experience with us.>
Thanks again.
<You're welcome. James (Salty Dog)>

HLLE QUESTION 8/2/05
Hello, I have a Tenecor 180 gal FO setup with 2 wet dry filters moving 1200 gal per hour, Berlin turbo skimmer w/ ozone, 4 lbs of Tri-Base Carbon from Hyatt labs in one of the sumps, 10 Gal refugium in the other sump, Aqua UV 57w sterilizer. 10% aged H2O changes every 2 weeks, Trace elements dripped in daily to keep up with water evaporation. Tank is grounded.  Tank is meticulously kept but has some diatom algae. ( the skimmer has been modified by adding a limewood airstone don the middle and to the base and extending the neck and the
collection cup to twice normal size Tank Does receive some sunlight.
    Stocked w/ Large Naso Tang 4 yr, Purple Tang 9 yr, Fiji Foxface 4 yr, 3 clownfish 9 yr.  All fish have been doing great except that the Foxface has bad HLLE for 3 years and the Purple Tang has moderate HLLE but all fish act
normal ( i.e. eat like pigs cluster to tank top when I approach mild fish to fish aggression ) The tail fins of the tang and Foxface look a bit ragged but not infected.  The Perculas have actually spawned in this tank !!
    I feed 2-3x daily combination Nori w/ Selcon, Ocean Nutrition Form 2, Spectrum Thera A+ with Boyd Vita Chem, Spirulina flake..
    I recently added a beautiful Emperor Angel after 4 weeks of quarantine but 4 fish got a slight case of crypt ( first outbreak in 4 years ).  I decided to use hyposalinity to treat he display.  Inverts i.e. snails hermits & plants
were removed.  I lowered salinity over 4 days to 1.010 and it has worked great.
    I noticed that as I was lowering the salinity with RO water brought to a pH of 8.3 HLLE actually improved and there was noticeable fin regeneration in the tang !  Over the years I have noted that the only thing that has had any
effect on the HLLE is an improvement for 5-7 days after water changes and "control" of the HLLE since trace elements were dripped in.  Addition of Iodine does not do much other than make the algae bloom.  If I skip a water change things seem to worsen.
<Yes>
    Once I brought the salinity down to 1.010 and went to every 2 week water changes I noted now the angel is developing early signs of HLLE.
    Tank chemistry is great with pH 8.3 Nitrates less than 20 no nitrite or ammonia.  I am planning on adding 90 Lbs of cured LR, and getting the refuge going this time with Gracilaria or Chaeto, but after I bring the salinity back
up.  I have kept the Tri Base carbon in place now for 3 years and nitrate levels are still low therefore I have not removed it.  Any other suggestions ????
Thanks Jimmy
<The most common "cause" of HLLE is nutritional... deficiency of vitamins... but water quality plays an essential role as well... the single best thing you might do is to convert your wet-dries to other types of sump filters... Please read here:
http://wetwebmedia.com/tricklefaq2.htm
and here: http://wetwebmedia.com/hllefaqs.htm
and the linked files above where you will lead yourself to your apparent options. Bob Fenner>

HLLE-And Poor Husbandry-Not Just A Coincidence... 7/22/05
I've read through the facts, and I see that HLLE (head and lateral line erosion) is caused by poor diet, poor water quality, stray voltage.. etc.
<Well, it's not 100% certain what it is, but those seem to be the likely culprits!>
My question is this. I recently moved from Baton Rouge to Kenner (Louisiana) and I'm sure you will agree with me when I say that usually the local fish stores and the way they do things is generally the way the hobbyists end up doing things in their own aquarium, in that city. (wow did that make sense??)
<I think I'm following ya'!>
What I mean is that there really is only one prominent shop in B.R., and they rely heavily on hang-on-the-back filtration, really don't utilize ozonizers, use one brand of protein skimmer etc.
<I see...While mechanical filter systems have their place, I think it is a bit narrow minded to use only one methodology to the exclusion of all others....Whether it's in Baton Rouge, Boise, Honolulu, or Outer Mongolia! Hobbyists and businesses need to be open to different ideas and accept the way that there is no single best way to do things in this hobby.>
And the hobbyists that shop there have tanks that reflect this method. I noticed in a lot of aquariums in Baton Rouge that HLLE was present, but obviously caused by the lack of water quality.  In these cases it was easily reversed.
<Very true in most cases, as you correctly observed.>
In New Orleans, there are several shops that utilize sumps, ozonizers, and calcium reactors, and the hobbyists out this way are really more in tune with their systems, and water quality. They feed really well, and frequently, and do smaller water changes.
<I think that these methods are better long-term solutions for most hobbyists, despite the initial perception among many novice fish keepers and even some (retailers) that they are "more expensive", "more complicated", etc. In the long run, a better system, properly set up for a sustainable population of fishes will save countless dollars and needless fish and invert deaths. This is NOT a cheap hobby, but an initial investment will pay dividends down the line...We're on the same page here, my friend! Off the soapbox for me now!>
I'm doing maintenance and have noticed, oddly enough, that even though the water quality is drastically better, and fish are getting a better diet and (theoretically) they should have no HLLE....but it is a prominent issue that I'm dealing with. I'm talking sever cases, and not just on tangs. And the only thing these customers of mine have in common is that they all have ozonizers. And the ones that don't, do not have HLLE.
<Well, in the absence of other filtration adjuncts and means to improve water quality, ozone would have a much greater impact. It is an extremely valuable ally in the maintenance of healthy systems, if properly applied. Good observation by you.>
I'm about to start treating with Zoe and Zoecon, (have had remarkable success with these products in the past) and my question to you is should I experiment with cutting down on the ozone? Placing it on a timer? How long should the ozone run to be effective? They are currently on 24 hours a day.
<Well, I don't think that you need to run high levels of ozone, but you do want to check overall water quality parameters (such as nitrate, which is a great "yardstick" for measuring overall water quality), and it may be applicable to use a Redox controller to monitor ORP if you are a serious user of ozone...although that might be a bit over-the-top for many hobbyists, IMO. I think that, in the end- common sense stocking and overall good husbandry-including the use of ozone, if you feel it is warranted, is the best solution. Additives such as Zoe, Selcon, etc. are always nice to enhance the nutritional value of prepared foods. Also, menu items as simple as fresh macroalgae, such as Gracilaria, do wonders for many herbivorous Tangs and Rabbitfishes (which are notoriously susceptible to HLLE). You sound like you've got a great understanding of the problems and methods to address them!>
Is the HLLE and the ozone just an odd coincidence?
<I don't think so. The connection between the high water quality that ozone (or other good husbandry habits) affords is no coincidence, IMO. Hobbyists who use care in stocking, maintenance and overall husbandry seem to have a much lower occurrence rate of such problems, in my experience. Keep doing what you are doing, and preach the benefits of good husbandry and observation to your friends!>
Thanks (again) for your guidance, Niki -Coral Connection
<It was nice to hear from you, Niki! sounds like you've got it down good! BTW, for more on the HLLE condition and some good treatment ideas, do check out a recent article by good friend and WWM/"Conscientious Aquarist" on line magazine contributor Steven Pro on this very topic in "Reefkeeping" on line magazine. A very good, nuts-and-bolts analysis of this condition. Best of luck to you! Regards, Scott F.>

HLLE...(Cont'd.) 7/27/05
Hi again Scott,
<Hi there! Sorry for the delay in getting back to you!>
Terribly sorry to bug you, but I don't think I quite understood the answer. Would you say that the ozone might be lending a hand in the fish becoming heavily afflicted with HLLE?
<No, I don't think it is...I do think that if applied correctly, ozone can be a great assist in maintaining a cleaner environment, thus reducing the potential for diseases and maladies such as HLLE>
It seems that even though I treat with food supplements, and increase water change  (smaller more frequent) that the HLLE does not go away. (As it does with tanks that have no ozone)
The only correlation that I see between the tanks that have the HLLE that is not reversible is that the ozone is on 24 hours a day.  Best regards, Niki@Coral Connection
<Well, Niki- I've never seen or heard of ozone as being a contributor to more serious HLLE condition. On the other hand, there is not a whole lot known about the real causes and "cures" for the condition in question. Much of what we "know" about HLLE is from anecdotal observations, etc. It's important to follow up on your theory/observation. Why not try reducing the period of time when you dose ozone, or even eliminating it entirely? Since you're basically testing a hypothesis, it's worth a try! Maybe there is a correlation in your case...Good luck! Regards, Scott F.>

Again on HLLD
Dear Bob,
<Steven Pro this morning.>
As the values of my tank are now ok (you might remember my tribulations with achieving reasonable nitrites)
<I really do not remember. We get 30 up to 60 emails daily and now have 5 individuals regularly answering emails with a few other's assistance at times.>
I am entertaining the idea of putting a Koran Angel in it after it has matured for a few months with live rock, algae and critters and a couple of clowns. I have read Korans are prone to HLLD.
<As are all Angelfish and Surgeonfish.>
Briefly, how can I best avoid it
<High quality, varied diet and optimum water quality. You can read much more about this affliction here http://www.wetwebmedia.com/hllefaqs.htm>
(I will be feeding krill, squid, minced lancefish, mussel, dried seaweed and flakes/pellets all enhanced with vitamins and I will do water changes weekly -10-15%- with nitrate resin treated tap water left to mature before I add the salt)?
<I would use more herbivorous based foods and also something with sponge matter in it.>
I also add iodine regularly, but I read something about iodide on your site. I am no chemist - I am a musicologist - so can you please explain what iodide is and how to get hold of it if I have to?
<It should be available at any pet store. See here for additional information http://www.wetwebmedia.com/iodfaqs.htm>
How often will I have to feed it?
<Dose as per instructions>
Also I read that salt quality is important and I found out that Kent Marine salt that I am using is not that great (nor is sera, my next possible alternative). That's your opinion on the subject?
<I like and use Aquarium Systems products; Instant Ocean or Reef Crystals.>
Thanks again, Massimo
<You are welcome. -Steven Pro>

HLLE
Hello crew, I am a 15 year old reef hobbyist that has a question. My cherub angel (C. argi) has developed HLLE around his eyes in the last few months. It isn't very bad, and hasn't spread to the lateral line, but it seems to have spread a little more around the eyes. The food I use is a frozen homemade blended mix of carnivore marine supreme, herbivore marine supreme, seaweed selects, brine shrimp, and Spirulina flakes with Zoë mixed in.
<I would concentrate more on the herbivore foods and lose the carnivore and brine shrimp would be better replaced with mysis shrimp.>
Is this not a nutritious enough diet?
<It sounds ok. Note that HLLE is linked to both diet and overall water quality. Near reef tank conditions are also needed to keep in tip top shape.>
I always thought it was adequate. Another thing is I don't feed THAT often, not every day at least, but there is plenty of liverock with microalgae to feed on. Could my angel be developing HLLE because I don't feed often enough?
<It is possible, but I would also examine water quality, too. A pH at or above 8.2 is needed along with nitrates as close to zero as possible.>
The angel has a nice shape to him, no visible skinniness. Thanks for any help! Be proud of that web site! ~Andy
<Thank you very much Andy and good luck to you and your fish! -Steven Pro>
              
Re: HLLE
Hello, thank you tremendously for the quick response! The tank has been set up for 5 years. I honestly don't think it's the water quality. I have 0 nitrate, 0 nitrite, 0 ammonia, and the pH usually ranges from 8.0 to 8.2 [yes a little low, but I doubt it would cause HLLE in itself, then again I'm not an expert =) ].
<It could be an indication of a build up of dissolved organics. You see nitrate in and of itself is not harmful to fish, but it is a good indicator that we use to deduce the level of dissolved organics. A low pH is similar. It may be time to increase the frequency or amount of your water changes or to make sure your skimmer is working well. You should strive to make it produce dark product daily.>
All my corals thrive (xenia, GSP, mushrooms), as do the mobile invertebrates (emerald and hermit crabs, cleaner shrimp, green brittle star, various snails). The xenia pulses like crazy and is an absolute weed, (growing off the back wall). What do you know about the
Hexamita/Octomita parasites, could they be the causative agent, and treated?
<As far as I know, these are only for freshwater problems.>
My dad is an electrical engineer, and seriously doubts that stray voltage or electricity could cause any damage.
<He is not the only one. I don't buy that either.>
What do you guys know about the stray voltage issue?
<There is no definitive link that I know of.>
Maybe it is the nutrition, I just do not know. I've heard something about lack of iodine in the diet?
<Perhaps modify the diet as I mentioned previously and include some American Marine Selcon and Boyd's Vita-Chem instead of the Zoë.>
Anyways thank you for your help =).
<Good luck to you! -Steven Pro>

Carbon Causing HLLE?
Hi Crew, thanks for taking my question.
<Sure! Scott F. with you today!>
First let me give you a brief history of my situation.
I have a hippo tang that developed hole in head disease early on. It is stable (some scaring around the head) and has been there for about a year and a half or so. Anyway, he developed ich a little while back, I believe it was from a wrasse that I added without quarantine.
<A lesson learned, huh?>
I put all my fish, 1 tang, 2 clowns and the wrasse in a 35 gallon plastic container (quarantine) for 8 weeks while I let the tank run fishless to get rid of the parasites. I decided to use the  "siphoning bottom of tank everyday" method to cure (no copper) and it worked great.
<Well done! Glad to hear that!>
Now to the point. During the eight weeks in quarantine, my hippo tang showed tremendous improvement regarding the HLLE, the scarring around his head was reduced by at least 50%. Problem is, I put him back in the display tank and all the progress has reversed and the scaring went back to the way it was. There is no way the water quality in the quarantine tank was better than the display. I was using tap water, a power head, a heater and a sponge filter. The display tank  gets RO + DI water, 20% bi weekly water changes, live rock, live sand, better diet, steady temp, etc. So I figured it was the lack of carbon use that helped reverse HLLE. I did not use Carbon at all in the quarantine and run it constantly in my display tank. So I want to experiment and stop using Carbon in my display tank.
<Well, that could be one possibility...I'm quite skeptical, because use of carbon far outweighs any possible ill effects that could happen, IMO. Yes, some people claim that carbon depletes trace elements, but if you are conducting regular water changes, this argument doesn't hold up, IMO. Anecdotally, you could proceed under the hypothesis that carbon contributed to the HLLE condition, but I don't know how it will work out. An interesting experiment, however. I commend you for trying! Do consider other possibilities, such as "stray voltage" in the display tank, or other possible environmental factors, too...Test for all of the basic parameters, and then some!>
Will this effect my Coral in anyway? I have a Bubble, Torch, Candy Cane, Various Polyps and Xenia.
<Well, activated carbon helps remove all sorts of allelopathic compounds that are released by corals on a regular basis. You might see some differences in the health of these animals if you discontinue its use in this tank.>
Should I increase my water changes, or is it not necessary?
<I'd consider more frequent water changes to help compensate>
Will the protein skimmer pick up the slack? I use a Aqua-C Remora.
<Aggressive protein skimming will definitely help, too.>
Thanks for you input. Ang.
<My pleasure, Ang. Do test your theory, but also look at other possible factors along the way...I'm sure that you'll have some interesting results to report! Good luck! Regards, Scott F>

Damage Caused By Copper? Or HLLE?
Hi, 
<Hello there! Scott F. here today!>
I've got a question about head and lateral line disease. I recently treated my purple tang with copper for a presumed parasite, possibly ich. He was in copper sulfate for 9 days at the recommended dosage and using a copper test kit to measure levels. He was looking good up until the last day of treatment when I noticed he appeared to be getting head and lateral line disease which I presume is due to the copper.
<Probably not HLLE, but it is possibly a skin "reaction" to the copper. I've seen this in other fishes before following copper treatment. HLLE is generally thought to be a result of long-term nutritional and environmental lapses.>
He was fed well with its usual diet ( I've had him for 2 years) and was and still is eating very well. The tang is now back in a tank with copper free water with 0 ammonia, nitrates and nitrites. My question is will this resolve on its own with good water quality, proper diet and iodine and vitamin supplements.
<It should. If it is damage caused by the copper, it certainly can heal up. HLLE-related symptoms also can spontaneously go into remission and disappear over time, with attention to good environmental conditions and diet>
Also is the disfigurement permanent to the fish. Thanks for the help, Larry in Minnesota.
<In my experience, Larry, the damage that you see is not permanent. There is no 100% guarantee, but keep doing what you're doing and hope for the best! Regards, Scott F> 

More then HLLE?
Dear Mr. Fenner,
I am wondering if you can help me understand something I have read in your book about Yellow Tangs. I have a 80 gallon reef aquarium, 20 gallon sump/refugium. Berlin Skimmer, 70 pounds of live rock. The only fish who calls it home is my yellow tang. My water quality after months of fiddling around has reached a perfect balance. No stray voltage (had it tested.)
I am treated this tang for HLLE by way of Zoe vitamin supplements and Iodine. It is a slow process but thanks to your web sites support, as well as your book, I feel I have made progress.
<Ah, good to read of your continuing progress>
My question to you is about a passage in your book about an unwanted variety of yellow tang. A yellow-white morph. the kind that has the white band across the body and is rather startling to see at night. The tang I have now falls into that description. A gift from my husband who knew I wanted a tang for many years, and now he is having a guilt problem thinking he (the tang) is a sickly doomed fish.
I wonder if you could go into further detail about what causes this.
<Very, very likely what you are observing is "fright", night coloration... not the novel genetic anomaly mentioned in CMA>
Is it the same factors as HLLE? 
<No>
If not is there anything I might do to benefit this fish?
<Certainly. Most any/all things that benefit water quality, nutrition, the mental/emotional well-being of this animal and its tankmates. Principally the addition of live rock and macro-algae here... Or in a tied-in sump/refugium... would stabilize water quality, add foods... Please read over this and related sections on our site: http://wetwebmedia.com/yellowtf.htm>
The tangs I see at the fish store are a golden yellow (going by the Crayola crayon color scale) and mine is a pale lemon yellow.
I hope that if you are able you could send an answer or direct me to a book or web site that could help. Any advice is so very welcome. 
<Yours color will come back... through an understanding of the underlying causes of such loss... water conditions, nutrition. As stated, please read through the WWM site>
Pictures of the Tang can be provided as well. Also I must add the white band that runs across her body is visible during the day (4X96 watt power compact lights)
Thank you
Chris
<Your intelligence and caring show through your writing. You will be successful. Bob Fenner>

Re: More then HLLE?
Mr Fenner,
Your quick response to my inquires about the health of my yellow tang was greatly appreciated. I have just gone through you FAQ about yellow tangs again as well as the section devoted to Macro-algae.
Our water quality is as good as it gets. We only battle Alk. levels falling too low at times.
<This is quite common... captive systems are reductive environments>
We test our water three times a week and we are always able to correct any problems ASAP. We have not thus far had any dramatic rise or fall that has given cause for concern.
Our sump has LR (our tank has 70lbs, well seeded) and different forms of macro-algae. None of which our tang has accepted as a meal. 
<Have you tried strips of Nori algae... can be had from oriental sections/food stores>
We will endeavor to order from FFX new cultures of macro that we find that tangs enjoys (have learned more of those on your web site.)
I think one area we have grossly misjudged has been the environment of the tank. Not speaking of the water quality but more of the arrangement of the LR. This afternoon when my husband gets home we will rearrange the rock in hope of providing a more natural reef appearance. More caves and overhangs, etc. We also plan to add three green Chromis.
<Very good ideas>
The yellow tang is the only inhabitant in the tank right now. We have gone so slowly when building this reef that we were blinded to the fact the she might actually need "friends" sooner rather then later. :)
<Yes>
Your advice has been taken to heart and will be implemented. I hope you are not apposed to updates in the future. Thank you again for all of your help!
Chris
<A pleasure my friends. Bob Fenner>

Concerns about stray electricity
Mr. Fenner I would appreciate if you could perhaps give me some suggestions.
I have a fish only 180 gallon tank, I have a Harlequin Tusk, a Marine Betta, a Blue Face Angel, a X-mas wars, and a black Dalmatian puffer. My pH, salinity, nitrate, nitrite, ammonia are perfect, These fish eat better than I do, I feed them shrimp, squid, krill, and a verity of pellet foods, I have had then for about a year. with out no problem till now, my Blue face has lost all of its blue on his face my X-mass wrasse seems to have HLLE decease along with the Marine Betta. I gave back to the fish store the Blue face so that they hold it for me for a while to see what would happen and the blue started to come back again, the owner of the fish store told me that that probably had some type of an electrical current in my tank, so I purchased a ground probe, took back the Blue Face and the Blue that had returned while it was at his store again came off I grounded the 4MD pump that I have from the wet-dry going back to the aquarium. I have a Rio 2100 pump that goes to my UV, and a Mag-Drive pump that goes to my protein skimmer. My question is this. SINCE THESE PUMPS ARE UNDER WATER HOW CAN I GROUND THEM, AND WHAT CAN BUY WHERE I CAN MEASURE IF THERE IS ANY ELECTRICAL CURRENT INSIDE MY TANK.
Please, help me I would really hate loosing these fishes.
<Thanks for all the useful information here. The sealed pumps are very unlikely leaking electrical potential into your system. They are grounded through their plugs... and can be checked for ground faults by having them wired through GFCI protected circuits. Read here: http://www.wetwebmedia.com/gfiuseagb.htm
Electricity in an aquatic system can be checked with simple "multi-meter" test gear that measures down to the "milli" range... Now, more to the point. HLLE conditions are attributed to "stray voltage", "poor water quality", "Octomita/Hexamita necatrix"... and these co-factors may well play some role... these conditions are cured with nutritional make-up... Please read here: http://www.wetwebmedia.com/hllefaqs.htm
Be chatting. Bob Fenner>
Ramon Donestevez

Tangs/HLLE
I have a blue regal and a yellow eyed tang in two different aquariums, both have had HLLE for quite some time now. I have asked many different people on how to help clear this up and have gotten a variety of answers, most stating water quality, diet, live rock, electrical current in the water and vitamins. 
<many theories yes... none definitive. Diet is at least contributory... electricity is a weak argument. Live rock with lush macroalgae is clearly a help. Natural sunlight is perhaps the best solution of all>
I have tried just about everything I've been told to help clear them up. The blue regal has shown some improvement, however the yellow eyed has gotten much worse. (All of my other fish are in excellent health) They are both very healthy looking otherwise and are veracious eaters. 
<what kind of diet?>
I saw on your Q & A page about the use of baby vitamins, iodide and vitamin prep s. I have never heard this, what dosage would you use for the baby vitamins? I have 90 and 70 gallon tank. As for the iodide and vitamin prep s, I'm not sure what they are, where they can be found or what dosage to use. Is there anything else besides this that I can do? I try to do the best I can for my pets and any advice will be greatly appreciated, Thanks, Georgia
<the best way to dose vitamin supplements is in a prepared recipe to be ingested (much better than putting in the water). I like using the baby vitamins and Selcon (HUFA supplement... an aquarium product). Do use the Google search tool on this site and beyond to discover fish food recipes that suit your fish load (mostly herbivorous fishes). Making your own fish food is a great way to save money and offer high quality food to your fishes. Kindly>

Tang with HLLE
Hi again,
How long does it take for most fish to developed HLLE?
<It depends on the fish, diet, system, etc.>
The reason being is that I have two (one yellow, one purple) tangs and only the yellow has HLLE. The fish are fed a varied diet of Nori, bloodworms (frozen and dried), dried daphnia, krill, a variation of Bob's mix (krill, clams, squid, cod, shrimp, octopus, silversides and Kent Zoe), as well as an omnivore and carnivore frozen mix from San Francisco Bay Brand.
<A little too much meaty foods for these Tangs. I would drop the omnivore and carnivore diets first and get a herbivore food.>
The tank is grounded and I do a 10% water change weekly as well as topping of the tank with a Kalk mix. Would there be a cause that would only affect one fish?
<The time in captivity is your most probably cause.>
I have had the yellow fish for a few years, so is it possible that age could be a factor?
<Yes>
And I have the purple for about a year, so I would think that if there was something I was neglecting or doing wrong, it would appear on him as well.
<It may in time.>
Any suggestions?
<More vegetable matter, Nori fed daily plus some sort of herbivore diet like Formula II from Ocean Nutrition. I am sure San Francisco Bay Brand has something familiar. I am just use to Ocean Nutrition foods. You may also want to soak some of their foods in Boyd's Vita-Chem and American Marine Selcon. Again, there maybe similar products. These are just what I am used to.>
Thanks again, Kim
<You are welcome. -Steven Pro>

Hole In The Head Disease (Hexamita)
Please could you give me any advice on treating Hole In The Head disease in Cichlids.
I have tried virtually all the tips on your website (vitamins/iodide etc) and also Metronidazole but all to no avail. My affected fish is a Tilapia Butterkoferi (11") that was fine until about 6 months ago. 
<sometimes Hexamita is misdiagnosed. In many such cases the condition is simply an infection of the olfactory pores from poor water quality. Weekly water changes are necessary with such predatory fishes to keep DOC levels down. You may be able to cure this ailment with more frequent water changes with extra salt (1 tablespoon per 5 gallons). As such, it will take weekly or better for 6-8 weeks but can deliver success>
He is still feeding well (Cichlid Gold, earthworms, other invertebrates, prawns, peas plus catfish pellets) and is behaving normally but more 'holes' are still occurring above his eyes.
I have been told that this condition could be due to his age as the water quality in his tank is fine and he has a good diet. 
<have you tested Nitrate levels to confirm the quality of the water? Please do if not>
I have tried Broccoli as well but he won't touch this.
If the problem continues is death inevitable?
<not at all.. in fact, unlikely>
Any new information that you can give would be greatly appreciated as I am fast running out of ideas.
Thanks a lot, Ian Allen
<best regards, Anthony>