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Related FAQs: Treating Disease, Marine Diseases 2, Marine Diseases 3, Marine Diseases 4, Marine Diseases 5, Marine Diseases 6, Marine Diseases 7, Marine Disease 8, TDiseases 9, Diseases 10, Diseases 11,

Related Articles: Tank Troubleshooting, Toxic Tank Conditions, Environmental Disease (incl. Lymphocystis), Nutritional Disease, Infectious Diseases, Parasitic Diseases, Wound Management (/aquarists), A Livestock Treatment System

/The Conscientious Aquarist Series:

The Three Sets of Factors that Determine Livestock Health


By Bob Fenner


Just what is disease, or its antithesis health?

Once at a hobbyist conference I heard a pitch called "Fish Are Designed to Die" (Image1: Koi in pond),

in which the presenter regaled us with all the reasons (parasites, poor water quality (Image2: Furuncular condition in goldfish), 

stress from so many sources (Image3: Koi in rough netting),

nutritional deficiencies (Image4: Koran with HLLE)… 

why expensive pond fishes should not make it in captivity. Considering all that can go wrong in the wonderful cascade of electrons which is life, it is indeed a marvel that there is so much vitality about.

Disease is "any deviation from a normal or healthy condition" as a definition will suffice for our discussion here. As such there are many types of disease, with a few ways of classifying them. Most prominent of these sources of non-health are genetic

(Image: a genetically tweak-mouthed Cirrhilabrus labouti), 

Environmental, nutritional, social factors, infectious and parasitic pathogens. As conscientious aquarists we need to be aware of the root causes of diseases of our captive charges and do our best to identify, prevent, and if necessary treat to cure them or reduce their ill effects.

And there is much aquarists can and should do. Careful, intelligent livestock selection, properly acclimated and kept in an optimized, stable environment with its myriad factors, plus excluding and weakening infectious organisms are the primary aspects of prevention and control of disease.

A very useful model/pictogram detailing the three sets of factors determining the well being of any system is presented here (Image6: empty three sets), along with related notes, specific action to take in successful aquatic husbandry. Like many early idea-sets, this empirical model is a consequence of direct observation, tremendous trial and errors, and proof by utility. I encourage you to think deeply about this. Note the first sentence in this paragraph; "determine" is used, not "influence", and well being of any "system". The "three sets of factors" elucidated here are lessons beyond a small aquatic microcosm; they are the same conditions that determine the viability of an individual, planet or business corporation.

Factors Determining Health, The Three Sets:

The three sets of factors determining the health or well being of any aquatic system are 

1. Initial state or condition

2. Suitability of the environment

3. The presence and degree of infectiousness of disease-causing organisms

All three are separate and yet interdependent upon each other, hence the interlocking circles of the accompanying pictograph. In the "real world" of aquarium culture it is ideal to select for and create the best circumstances for each of the three sets of factors; though, practically speaking, if two of the three are realized, livestock losses are greatly minimized. By using this model in your planning, execution and maintenance of a captive aquatic system to mentally keep straight the most important aspects of health control and their relation, you will lose many less organisms.

Let's further describe and expand on these sets of factors.

1. Initial State of Health:

Your livestock's' initial condition is a function of its genetic heritage coupled with its developmental history. Similar to cultural discussions of "nature versus nurture" in our species, how can an individual, population or species become something more than its genetic makeup? Or discounting DNA, how important is ontogeny, the development of the one or many of a kind? Obviously both are crucial, to have the genetic potential to "fit" an environment, and the "lucky" circumstances generationally to grow up and reproduce within it.

How can you assess the initial state of health of your livestock? By study and observation you know some species (Images: Moorish idols vs. Heniochus butterflyfishes, source locations (Images: Choerodon (Tuskfish) from the Philippines., Australia), sizes of livestock (Images: Too small (2"), large (8"), about right size (4") Saddle-Back Butterflies) are hardier/touchier than others. With practice you will know how to pick out healthy individuals. We'll elaborate on this later under Aspects of Prevention & Control.

2. Suitability of the Environment:

The suitability of the environment incorporates an amazingly large collection of sub-factors, chemical, physical and biological.

A) Chemical/Physical Aspects of Environmental Stability:

Consider pH, the measure of relative acidity/alkalinity of aqueous solutions. The pH point, fluctuation and stability influence almost all biological reactions. A prime example is the relationship of pH, temperature and ammonia toxicity. Elevated pH (the higher the worse), with higher temperature, yield situations of much greater ammonia toxicity. Reciprocally, lowering pH and temperature alleviate the poisonous affects of ammonia

ii) Alkaline/acidic reserve is related phenomena, representing a measure of resistance to change or shift in pH. In small captive aquatic volumes it is often practical to know how much is enough such reserve one has. Feeding too much food to too much life can drive a pH down quickly once the alkaline reserve in a given range is exhausted. Providing buffering action through supplementation and maintenance, especially water changes forestall drops into lower pHs.

iii) Reduction-Oxidation, temperature, carbon dioxide, calcium, strontium…. Plus many more, could be listed as chemical/physical phenomena that have high and low limits and a need to display some semblance of stability to permit life.

iv) Bio-Geo-Chemical Cycling Considerations… nitrogen in ammonia, nitrite, nitrate. Indeed hundreds of "cycles" exert their effects (and vice versa) on the life within and around them. Ammonia poisoning from incomplete establishment of cycling is and has been the historical number one killer of captive aquatics. It probably is number two as well, as a contributor to other stresses that account for mortality.

v. (Image: plants and gravel) is yet another aspect of the physical make-up of the non-living environment that substantially contributes to the health of biota. How important is the break-up of space, hiding places, dark spots out of the light to living organisms? Critically so.


vi) Light/lighting; quality, quantity, duration and even regularity are known to strongly effect the health of aquatic life. Photosynthesis is obviously impossible without proper illumination (Images: planted tank, Acropora gemmifera), fishes can be blinded over time by too much light, notably lions (Image: Pterois volitans), but practically all livestock benefits from a regular lighting regimen. Use TIMERS.


B) Biological Aspects of Environmental Stability:

Population dynamics includes such ideas as order of introduction, pecking order and crowding; all significant contributors to the individuals living in your system. I have seen many "to the death" fights brought on by mis-introduction of two too-similar marine angelfishes (Images: Pomacanthus arcuatus, P. annularis, P. chrysurus). 

  Even the act of changing familiarity is demonstrably stressful to fishes. Often a pond of koi (Image: carp, Cyprinus carpio) will break down with bacterial infection (Images: early onset, Furuncular sores) on the placement of a new individual, though it was apparently "clean" in its last locale. Observation in the wild and in captivity points to the high degree of regularity fish life depends on in the living and non-living components of their environment.

Sex ratio, and number of individuals (pairs, single, many) are likewise consequential in captive systems. Think of the fancy basses of the subfamily Anthiinae (Image: Anthias in RS). How many males to a harem? One alpha only. The same with communities of dwarf angels (Image: Flame angel). What happens when the number one male of a Thalassoma wrasse (Images: T. lucasanum) group perishes? The highest ranked female becomes the dominant male within a few weeks. How many Heniochus should be kept together? The more the merrier.


C) Foods/Feeding as Aspects of Environmental Stability:

The types, format, quantity, food value, frequency and method of delivery are all important parts of the behavior and nutrition of feeding. Think how stressful it is to you to not get the foods you prefer properly prepared and presented, at a regular interval, nutritionally complete, in a "conducively" pleasant consuming environment.

D) Almost Infinity:

How many more environmental criteria can you think of? Obviously this is not an exhaustive list of contributing environmental factors, such a counting would be vast indeed, detailing all interactions, chemical, physical, and biological, conscious and not that each organism has with their world.

3. Presence and Degree of Pathogenicity of Disease-Causing Organisms 

Absolutely no infection or parasitic disease can occur without its causative biological mechanism. Where would black spot disease (Images: Paravortex, Yellow Tang) come from if not imported into a system on  Yellow Tang host? Certainly not from thin air. Specific pathogen free livestock is a dream that is near impossible to attain, but much can and should be done to "knock off" the majority of external parasites and weaken the rest. 

Consideration of biological agent disease principally involves:

The number of parasitic and infectious species,

Their respective population, or load of agents per host, and

Their degree of infectiousness, or hyperinfectivity.

Having more types and numbers of parasitic and/or infectious (bacterial, fungal, viral (Image: Lymphocystis on a Queen Angel) species on a host is directly positively correlated with a loss of vitality and increased mortality. Less well elucidated is the synergism of hyper-infection in aquarium livestock. Once a biological agent problem "gets going" our subjective evaluation of the condition switches from "chronic" to "acute". An excellent though sad example is the occasional pandemic of "ana aki" (Japanese), "hole in the side" or furunculosis sores (Image: koi with ventral sore) associated with Aeromonas bacteria. In "good" years, this condition appears as a non-debilitating disfiguring open wound on one or a few coldwater fishes in a pond. In bad years, many or all piscine livestock die within a few days to weeks with massive internal bleeding.

What triggers this change in infectiousness? Is it a genetic nuance such as this and that new strain of influenzas in humans? Is it somehow related to that elusive sylph "water quality", the polyglot which is "nutrition"? Poor development or a result of built-in difficulties pre-Diaspora from the livestock's' common origins, i.e. a genetic "time-bomb"?

Do you start to see the usefulness of this "Three sets of factors" model? All three of these sets of factors are intimately tied together in outright determining the health of your livestock. By investigating, testing, and acting on these parameters you can strongly tilt the balance of health/disease in your livestock's favor.

Let's carry this discussion along to consider specifically what you can do to optimize each of these three sets of factors determining livestock health in terms of

Aspects of Prevention & Control: 

Doing the best you can for your aquatic charges in two of the three sets of factors listed will get you by in many if not most cases. The conscientious aquarist will shoot for all three. This lofty goal is within your grasp. Here is an itemization of specific actions for your edification.

1. Initial State of Health:

Selection; a/the secret of keeping healthy livestock is no mystery at all. You want to start with the healthiest, most likely to flourish-in-your-care individual/s. This can be a little tricky, as wild stocks purposely disguise any infirmity (lest predators seeking the easiest prey consume them). How can you tell how roughly the handling and shipping has been?

Appearance, behavior: Knowledge is paramount here. What does a healthy individual look like? How does it behave? Should it be "out and about" or is skulking in the corner ala the basses like (Images: Liopropoma, Epinephelus merra) … natural? Is the animal curious about its surroundings, your presence? Is its bright coloring a warning sign that it's been cyanided?


Source: can be extremely important; the regal angel, Pygoplites diacanthus rarely lives collected out of the Indo-Pacific ; ones from the Red Sea are quite hardy (Images: from both). Likewise, here again the example of the wrasse called the Harlequin Tuskfish. It's tough when it hails from Australia and frail from the Philippines. Ask your dealer, or better still check their manifest/invoice for the source of your livestock. Captive bred and preferred-places of origin are better than cheap, sick and soon-dead livestock.

Feeding: is it? Though not foolproof, the fact that a captive is feeding is a strong indication of its viability. Sufficiently cyanided organisms rarely eat, or if they do, perish soon afterward. A feeding response is indicative of further adaptive behavior.

Time on Hand: how long has the specimen been there? The vast majority (99%+) of marines and more than half of freshwater livestock is wild-caught. Generally there is a matter of days to a couple of weeks time between its capture and your seeing it. When do most losses occur? Right around this time, dropping off rapidly as time goes on. When in doubt as to a purchase, wait. Which brings us to

Purchasing Techniques:

a. Assessing the store, personnel: how much they know, care and practice contributes/detracts from the health of their livestock. How do they rate? Would you put your fishes, non-fishes in their systems? If not, then why buy from them? (Image: Wet Pets LFS)


b. The deposit & waiting game: especially for expensive and questionable buys, putting earnest money down to "hold" a purchase for a few days to a couple of weeks should work out as an advantage to everyone. You for the possibility of avoiding "anomalous loss", and the retailer for the same, plus "free advertising" of the livestock for future purchasers.

2. Suitability of the Environment:

Here the key words are Optimized and Stabilized; utilizing a

System as large as possible,

Properly set-up

Testing/Monitoring your water quality.

Utilizing appropriate Decoration/Habitat for your livestock beyond/beside aesthetic considerations, and carefully

Observing Your Livestock

Per their health, interaction on acclimation, introduction, feeding and

Routine maintenance, especially frequent, partial water changes.

Patience & Moderation (Yours): Never to discount the human factor, you've got to take your time in

Initial set-up. Planning, assembling, testing all gear.

Stocking. Per a scheme built around a central theme, biotope, and compatible livestock.

Feeding. Varied foods, assuring all are getting nutrified, not just ingesting.

Treatments. If/when necessary, which brings us to

3. Presence and Degree of Pathogenicity of Disease-Causing Organisms: 

Once again:

Knowledge and intelligence on your part are requisite. What is the root cause of your apparent difficulty? Are you really sure you are witnessing a biological disease agent, and not just a poor water-quality, incomplete nutrition, anti-social reaction? How are you going to be aware of what to do? Reading (Image48: Baensch books) on the subjects, discourse with other hobbyists, attending shows, talks, videos.

Quarantine/Dips-baths. All new livestock should be kept apart from established stock, out of the main-display system for a good two weeks. For collectors, transhippers, wholesalers at least routine dipping, preventative baths should be administered to fishes and corals (Images49,50: brown jelly infection of coral, cut marks on a Hemitaurichthys). If this advice is followed, medications should only be administered within a
Treatment Tank. Were all this so, our hobby interest would be ten times the size and vigor, as many fewer organisms would be unnecessarily lost, and the hobbyist discouraged to the point of dropping out. A separate tank with filtration, heating, a cover should be available to run in tandem with your main-display tank(s).
Treatments themselves are/should be a last resort. Many are quite toxic and you would be hard-pressed to find a few retailers that would agree that more livestock is killed by disease than by treatment. You are treating the whole system when you administer a chemical to your livestock; even with medicated foods (Image51: Making medicated food). There is an order of preference in treatment modes:

Biological, as in the use of cleaner shrimps and gobies (Images52,53: shrimp & goby) in saltwater systems.

Environmental manipulation, such as lowering specific gravity (or adding salt in freshwater systems), changing lighting, temperature… can be done to favor the hosts (your livestock) and disfavor their disease agents.

Chemical Treatments must involve consideration of efficacy: effectiveness, specificity, safety, and cost-effectiveness. As you would do with your own health or those of other humans entrusted in your care, investigate potential treatments before administration. Don't simply poor such and such in on one persons say so. Most such treatments do little good, indeed, more often cause more harm than good (Images: Dropsical goldfish, eye "fungus", Lymphocystis).

Per the model presented here, REVIEW the three principal sets of factors that determine the health of all systems and their sub-sets and make a concerted, coordinated effort to disclose the root causes of a problem. Seek to cure or ameliorate those conditions, only lastly resorting to outright chemical treatments; and then only knowing what you're treating for and how.

Bibliography/Further Reading:

Bassleer Biofish (for books, videos on disease)  

http://www.aquaworldnet.com/awmag/diseases.htm Fenner, Bob & Dave Huie. 1987. A livestock treatment system. FAMA 1/87.

Fenner, Bob. 1989. Parasitic diseases of cultured fishes: methods of their prevention and treatment. FAMA 10/89

Fenner, Bob 1992. Copper poisoning. FAMA 3/92.

Fenner, Bob. 1993. Chlorine, chloramine poisoning; or, how I treat my tapwater. FAMA 3/93.

Fenner, Bob 1993. An argument against "feeder" goldfish. FAMA 11/93.

Fenner, Robert 1998. Organism selection for the saltwater aquarist, pt.s 1-4. TFH 5-8/98.

Fenner, Robert M. 1998. The Conscientious Marine Aquarist; A Commonsense Handbook for Successful Saltwater Hobbyists. Microcosm, VT. 432pp.

Guerri, Elmer A. 1998. It's the stress; using the techniques of professional aquarists. AFM 3,4/98.

Halver, J.E. (ed.). 1989. Fish Nutrition. Academic Press, London. 798pp.

Hiatt, Snake. 1998. Major, macro, micronutrients. TFH 7/98

Johnson, Erik L. 1993. The insidious threat of stray voltage. TFH 7/93.

Noga, Edward J. 1996. Fish Disease, Diagnosis and Treatment. Mosby-Year Book Inc., St. Louis. 367pp.

Steffens, W. 1989. Principles of Fish Nutrition. Ellis Horwood, Chichester, UK. 384pp.

Watson, Thomas T. 1983. An ounce of prevention. TFH 9/83.

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