AQUARIUM DISEASE PREVENTION;
Steps to a Healthy Aquarium & Sick Fish
A Healthy Aquarium; Disease Prevention;
Disease prevention is probably one of the most important aspects of keeping a healthy aquarium, although a generalized statement.
I have kept up many aquariums (marine and freshwater) during my years of aquarium maintenance.
So over the years, I have experimented with many methods to lower disease incidence and increase fish longevity. Since I had many clients with dozens of aquarium under contract, which allowed me to utilize controlled tests to back up my observations in my literally 1000s of aquariums under my care over the years.
Taking measures to lower the chances of fish becoming sick is the best remedy for avoiding illness-related issues.
These diseases are often the result of poor water quality management which can be outright prevented.
It is also noteworthy that all the medications in the world will not cure a fish when poor water parameters and related issues exist in an aquarium; these issues MUST be corrected first!!
Here is the progression of how much of what I recommended came into full fruition:
My experience maintaining literally 10s of 1000s of aquariums gave me a unique perspective as compared to a pure hobbyist.
In fact, my largest client (the Bahooka Restaurant) was gained because an employee of the restaurant had an Arowana that was sick and none of the medications being advised to her by others were working.
I later utilized about a dozen aquariums in a room as well as the use of multiple aquariums at my now largest client (Coaster Co. of America).
More recently I have spent 1000s of hours in researching many of the results from my tests along with other's tests in order to provide a better explanation of these results. I do this to separate real fish keeping facts from anecdotal observations.
Back to the subject; during my time performing aquarium maintenance, I had to look at EVERY parameter and way to keep a healthy aquarium.
Reference: Aquarium Nitrogen Cycle; Raw Shrimp Cycling
Another example of one such myth is one about bio wheels.
This aspect of chemistry along with Redox, The Nitrogen Cycle, and the use of UV Sterilizer are among some of the most misunderstood aspects of aquarium keeping I have found based on conversations, emails, forum posts, etc.
What I found is that if ALL points of disease prevention are practiced; the healthier, more colorful, and long-living your fish will be.
I have had many forums criticize me for trying to scare aquarists into needing equipment such as "true" UV Sterilizers (not the UV clarifiers that are passed off as Sterilizers sold on Amazon & elsewhere) or for explaining the science in my aquarium chemistry article.
I personally have resisted adding disease charts because these proliferate all over the internet & elsewhere.
I recommend reading the companion article below about Medications/Treatments for more information that will help you make an educated choice when treatment of fish is required, rather than using a “dart on the wall” approach.
Also, I recommend reading some of the specific disease articles such as “Columnaris/ Saprolegnia” and many others found Here (or other disease specific articles found on the internet or elsewhere):
Please read on; Each step listed below is an important part of the Aquarium/Pond disease prevention puzzle (in particular steps 1-10)!
If what you want is a healthy successful aquarium, it is important that ALL steps are followed with the exception of step #13 (which is an important step if you are starting over after constant problems).
Please note that these steps ARE NOT in order of importance!!
 Cleanliness (Aquarium Cleaning):
The use of a recirculating cleaning filter such as a simple Sludge Remover Vacuum in between water changes can increase the efficiency of a cleaning where a tank has high amounts of organic mulm or has been through a period of disease exposure.
You also want to de-chlorinate the water so as to not add stress to the fish or environment.
Regular small incremental water changes are one of the best maintenance procedures you can perform (if not over done).
Here is a list of Reasons why Water Changes/Tank Maintenance on a regular basis is often important:
Please see this article for expanded information of these “Reasons”:
“AQUARIUM CLEANING; Reasons for Water Changes”
Another note to regular water changes; these are also important WHEN your fish are sick as well, being performed before each treatment.
Generally when fish are present, changes over 50% are not recommended as larger water changes can be difficult for fish to cope with large changes in mineralization, pH, etc. (which affect osmoregulation).
This again is where a Sludge Removing Vacuum can be a good idea to lower decomposing organic mulm that can affect water parameters and in turn lower fish disease resistance and even harbor disease pathogens such as Aeromonas.
As an example of what I am talking about based on my tests/studies, here are a few examples of why water changes are not a 100% positive method of eradication:
Another risk in "too large" of a water change is pH stress if new water alters the pH more than .5 on the logarithmic pH scale. Similar would be oxidative stress from too large a change in Redox.
The above examples are NOT to say that water changes (in particular a double 100% water change) do not improve the above situations, it is just that they should not be depended upon to be fail safe.
On the flip side, these large changes may be a good start in taking care of a non lethal detritus worm infestation, bacterial cloud, or even after certain methods of fishless cycling where being 100% certain is either not necessary or less of a concern.
For more about Aquarium Cleaning, please see this article:
 Good Filtration/Circulation:
I recommend two filters for redundancy, and I never totally throw out all media, rather I rinse part of the filter media in used aquarium water so as to preserve beneficial (aerobic) bacteria for proper biological filtration (ammonia and nitrite removal).
Keep in mind that the primary function of filters is to remove waste mechanically and biologically (& possibly chemically as well).
One question I am often asked is “Can I have too much Filtration”, the answer is yes, however let me qualify this answer; as many Reef Keepers can attest to.
So the point is to counter your aerobic bio filtration (which removes ammonia & nitrites but results in ever increasing nitrates) with water changes, use of micron cleaning filters, live plants such as Hornwort, products such as Purigen, Matrix, or Algone as well as de-nitrifying filter methods such as the use of live rock crumbles (marine tanks only), volcanic rock or similar that allows for anaerobic de-nitrification while not producing Hydrogen Sulfides.
Circulation goes hand in hand with filtration and often with more than one filter you will achieve good circulation and gas exchange (oxygen/CO2).
As with filtration, the question can be asked is "Can I have to much circulation?"
Here are a few suggested aquarium turnover rates:
 Use Level One or Higher Capable Ultra Violet Sterilization:
True Level One UV sterilizers help prevent many bacterial, fungal, and protozoa diseases.
The picture to the right documents this ability of a level one UVC Sterilizer to consistently lower oxidative stress in an aquarium!!
I would also state that some of the statements that UV Sterilizers are useless are FALSE and NOT based on any real scientific evidence, as they DO help for all fish.
Product Resource: Level One UV Sterilizers for Aquarium or Pond
Many quality UV sterilizers are not all that expensive especially when the cost of your fish, your time, and often the medications that may not be used are considered (which can easily cost more than the UV Sterilizer).
Another point to the use of UV Sterilizers is proper maintenance; often aquarium keepers install a UV Sterilizer and then forget about this device, however it is important to change your UV-C Bulb every six months for optimum performance!
Although no one step as outlined here in this article will solve all your aquatic problems, it is noteworthy that the use a properly installed UV Sterilizer is a one of the more proven steps to a healthy aquarium & fish longevity.
Testimonial from Everything-Aquatic Forum:
 Do not over feed!
Although this is an area where I have incomplete evidence (this does not mean the assumptions are wrong, just not totally proven), it is still an area where one should not short change your fish. I should also note that this IS a proven area when it comes to healthy anemones and coral in marine aquariums and plants in freshwater. The theory (and also as per my more limited tests/observations) is that the wavelengths that are beneficial for many animals such anemones as well as plants benefits fish in proper assimilation of nutrients as well as aiding in an balanced Redox Environment.
This starts with adequate lighting (the watts per gallon suggestion is outdated but still a good starting place) as per watts, lumens per watt and PAR (Photosynthetically Active Radiation).
The SHO & T2 lamps/fixtures are an another alternative, while the Premium AquaRay GroBeam LED Lights are second to none in the light energy produced and how close these lights duplicate natural sunlight.
UPDATE: From Redox Potential; As it Pertains to Aquariums
Please read this article for MUCH more about correct aquarium lighting:
I will also add as to lighting, although this is not as important a piece of the fish health puzzle as say Aquarium Cleaning/water changes, it is still a part especially when view as how many aspects of life can be traced back to the sun, even if indirectly. As well this new evidence as per the Aquarium Redox and wound healing further proves the importance of CORRECT lighting for fish only aquariums.
 Too Much Care
This section may sound ridiculous, however in both observations of customers who took care of their own aquariums (admittedly anecdotal) and my own my scientific tests of service clients aquariums I have noted that when a tank is “over cared for” that the end result is a more problematic aquarium.
What I mean by this statement are these points where both in tests and observations can have detrimental effect on an aquarium environment:
 Fish Old Age, Genetics, Irreversible Tissue Damage, or When NOT to Treat:
My apologies ahead of time for this section, as while I may seem harsh, it would not be honest of me to not provide a bit of a reality check in the care of certain fish. This does not mean we do not love our finned friends and provide them the best care possible, but sometimes this best care may not include dumping loads of medications in the water.
This is a subject I have made many observations over the years in fish "doctor" calls, etc.
An analogy would be expecting a miracle cure for a 70 year old person that has smoked a carton of cigarettes every day since 16 and who has had both parents die before 70 to respond the same way a 30 year old who never smoked, and still has grandparents alive in their 80s.
One thing is certain though and that is if a fish is not responding after making a couple legitimate attempts to treat, it is best to cease treatment, at least for a week.
As per "Old Age", this can vary greatly from fish to fish with genetics and water temperature playing a role as well.
While this might be more subjective in determining that this is the cause, what is not subjective is what to do to keep a fish comfortable during his/her last weeks as possible prolong the fish' life in a reasonably comfortable way (a fish that is still feeding is a good gauge from my experience).
Essentially most of the points outlined in this article apply just as much or maybe even more so to a weak geriatric fish!
As per medication use in older, genetically weak, or damaged fish; certainly the use of proven stronger medication therapy is worth attempting, however you will be doing yourself and your fish a favor to save your money and cease treatment if no improvement is forthcoming after a strong medication use is attempted.
Often with weak or older fish using generally more mild but safer treatments or simply boosting natural fish resistance is the best rout to follow
In the end if the fish ceases to eat, euthanization may be the best recourse.
 When you do treat for disease:
Another point is a that often a weak, old, or constantly stressed fish (such a Mbuna Cichlid that is at the bottom of the “pecking order” that is constantly harassed), will often be a starting point for opportunistic infections and as hard as it may be to do, removal of these fish which includes putting the fish down (out of his/her misery) is often albeit sadly a must do!
Also note that all the medication in the world will not help if you have not followed the above steps and keep good water conditions.
With this in mind, I strongly urge readers to read this article about the basics of successful fish treatment:
 Here are a Medications/ Treatments that SHOULD be kept on hand BEFORE you need them in an Emergency along a link for a product resource and with some information about each:
Please also remember to support the provider of largest FREE Aquarium/Pond information library ANYWHERE on the Internet before you utilize this information to purchase at Amazon, eBay or elsewhere. The provider is American Aquarium Products who also owns the "Aquarium/Pond Answers" website as well as sponsoring the excellent "Fish Beginner" website.
For more information about Aquarium Medications, please see this article:
“AQUARIUM MEDICATIONS, treatments, how they work, and which ones to use and not to use.”
 Purchase Fish from a Reputable Source:
This cannot be emphasized more, yet is quite simple, if you continue to have problems with a current source from your fish, try another (maybe you can get a good recommendation from a friend, etc.) If you find a good source, stick with it, even if the price is higher.
 When you purchase fish (Quarantine, baths, dips);
This is also an important step that both retailers and retail buyers of fish often miss the importance there-of.
Additional Marine Fish Acclimation Info:
*Besides the above, I ALWAYS at minimum provide a 3-5 minute pure freshwater dip (acclimated with marine buffers to the correct pH/KH to prevent stress)
This is 90% effective for prevention of Cryptocaryon and Oodinium. Consider the more advanced quarantine below.
Better or for fish shipped over longer time periods (such as fish purchased online or from overseas breeders, etc.)
*Lees Air Line Control Valve
*Hydor UG Heaters (these are safe in low water environments, unlike glass heaters)
Here is a video about "Basic" new fish acclimation:
Best Acclimation from Fish Store
Obviously time in shipment, amount of food in the fish’ gut at time of shipment, amount of fish and air in the bag will all affect how stressed the fish will be upon arrival especially as per CO2, ammonia/nitrites.
I should note that Kordon makes a “breathable” shipping bag that has quite an internet “buzz” going, however my interviews with several international shippers gives a mostly thumbs down to this product.
Here are a few points (+ or -) about this bag:
+ The bags allow oxygen and CO2 exchange which also lowers pH shock upon arrival.
+ Lowers size of shipping container as NO air needs to be added to the bag.
- The bags rupture easily; many shippers have told me that bag ruptures are triple normal.
- They still do not aid with ammonia/nitrites
- If bags come in contact with each other, they do not work well and packing them for the inevitable rough handling of shipping is nearly impossible or at least very time consuming.
- The bags do poorly with multiple fish per bag, in part because the bags are designed to hold small amounts of water so that fish can come close to the sides of the bags which multiple fish per bags usually does not allow.
- Higher cost.
- The bottom line is that the shippers I asked reported HIGHER losses with these bags.
Do not get me wrong, I think these are a unique idea, especially for smaller individual shipments, however based on my discussions with real world shippers that do not work well.
Cross Contamination of Equipment
As an aquarium maintenance professional for a few decades, this was a major concern and should be for any aquarium keeper who has more than one aquarium.
This becomes even more acute when one adds new fish to one tank/aquarium that this aquarium and any others do not come in contact in any way.
Steps to take (All are Important):
QUARANTINE OR HOSPITAL TANKS
If possible a quarantine or baths are good disease transfer preventative steps.
For a quarantine tank I recommend as large and aquarium as space allows for this, generally at least a 10 gallon (although this is not always possible and even a sterile 5 gallon bucket or Rubbermaid type container can work if need be).
Having this tank running constantly OR at least adding aged filter media is very important so as to not have ammonia spikes that will defeat the purpose of quarantine.
I recommend a bare tank with a seasoned high capacity Sponge Filter such as the AAP Hydro Sponge Filter. Running this sponge filter with an air pump is recommended over a power head water pump as the air pump method will provide a more gentle current that is generally less stressful to new fish.
After use of any treatment a bag of activated carbon can be placed under the base of the Sponge Filter for help in removal of medication.
Reference: Sponge Filter Use Information
A saltwater quarantine tank for prevention or treatment may be set using live rock and an air stone for bio filtration.
Product Resource: AAP HydroSponge Premium High Bio Capacity Aquarium Sponge Filters
It is important to note that when quarantine tanks/hospital tanks are employed that I have aquarists inadvertently cause more stress using this quarantine/hospital due to high ammonia/nitrite levels which is why I strongly recommend keeping a running sponge filter or similar for your quarantine/hospital tank. Simply moving a seasoned sponge filters or a piece or two of live rock from your display tank (for saltwater) is often all is required. If Methylene Blue is used, this may temporarily destroy your bacteria in you bio filter or live rock, however this is still a minor price to pay so as to not add further stress from high ammonia/nitrites, especially when the quarantine lasts more than 48 hours.
For treatment I recommend a Medicated Wonder Shell OR (not “and”) Methylene Blue combined with a Malachite Green products such as ParaGuard (use MG at half dose). For delicate fish, the Medicated Wonder Shell would be my choice since medications within the shell are introduced more slowly and this product also helps maintain a better Redox balance (which helps with fish immunity).
Monitor ammonia and other parameters (make sure there are no pH swings) while the fish are in quarantine.
Generally if your fish come from a good source 48 hours is enough, however up to a week up to six weeks may be needed for delicate or disease prone fish.
Metronidazole can be added to either the MB/ParaGuard method or Wonder Shell for added Trematode, Nematode, Monogenean Parasite prevention.
*SeaChem ParaGuard Ich, Fungus Treatment, Prevention
*Methylene Blue at AAP
*Medicated Wonder Shells
*SeaChem Metrononidazole; Parasite, Anaerobic Bacteria Treatment
Finally, it is important to cover this quarantine or hospital tank with a towel or similar so as to keep in near total darkness. What this achieves is to calm fish, lowering stress which in fact speeds recovery and/or allows for better disease prevention of new fish arrivals in quarantine.
I also have a theory as to why keeping a hospital tank in the dark often helps considerably (sometimes even main display aquarium); Fish instinctually hide and get stressed for their own fear of being harmed or even killed by other aquatic inhabitants. This then causes fish to often get even more sick from this stress. By calming the fish, both the medications and the fish' own natural defenses can work together for a more quick recovery or sometimes recovery itself when just using medications fails.
Often a quarantine tank is not possible or practical (as in my aquarium maintenance business). This is where a 30-45 minute bath is very useful for BOTH freshwater and saltwater. I would make sure to adjust pH so that there is no pH shock, especially for saltwater fish.
A bath can be performed in as little as 1 quart of water (or even less) or in a 1 gallon Rubbermaid (or similar) container or a small BARE tank (not gravel, décor though). I generally use a 1 quart pitcher with ½ teaspoon of salt and several drops of MB (I also recommend rubber gloves and old towels, rags, paper, etc spread around since Methylene Blue is messy and stains).
For freshwater I would add Methylene Blue at double normal tank treatment strength (as per bottle instructions) then add salt (NaCl) at about 1 teaspoon per gallon (Epsom Salts can also be uses at 1/4 teaspoon per gallon in baths used for treatment, especially in cases of bloat, water retention, selling, etc.)
The salt (regular salt; NaCl) can be increased for difficult treatments, especially with salt tolerant fish such as livebearers (it is best to slowly add dissolved salt to increase levels gently in salt amounts over 3 teaspoons per gallon, even in salt tolerant fish). Generally for most fish (even catfish based on University of Florida studies) 2 teaspoons per gallon can be tolerated for up to 30 minutes (many fish can tolerate 4 teaspoons per gallon), although if unsure about your fish’ tolerance, gradually add the salt via a dissolved solution during the first half of the bath.
A few more tips:
However, if a larger fish is in poor condition and question arises that the fish is already in a severely weakened condition, a bath or better, a dip may be attempted (see below for more about “dips”)
Potassium Permanganate can be substituted for Methylene Blue for treatment baths for ailments such as Flukes, cloudy eyes, & some parasite and bacterial infections. HOWEVER for "pure" preventative baths, ammonia poisoning or unknown problems, Methylene Blue is by far the better choice.
Product Resource: Potassium Permanganate, Clear Water from AAP
See this article under Potassium Permanganate or Methylene Blue for more:
Aquarium Medications; Chemical Treatments
Another key point is that Methylene Blue can quite SAFELY be overdosed as it takes high amounts with long term exposure to be toxic, while Potassium Permanganate should never be overdosed.
For saltwater I would add Methylene Blue at double normal tank treatment strength the Dilute the saltwater to 1.015 to 1.009, making sure your pH stays up by adding any buffers necessary before adding fish (1.009 is a must for Cryptocaryon prevention/removal). The purpose of adding or lowering salt (whether SW or FW) is to change osmotic pressure which is an aid to parasite removal as most parasites such as Ich or Cryptocaryon cannot tolerate these changes as well as fish.
Medications in Baths; Another options to baths is (IN ADDITION to the salts and Methylene Blue, but NOT combined with Potassium Permanganate), you can safely add many antibiotics at double normal recommended dose for the 30 minute bath, this can both increase the effectiveness of the bath and the antibiotic added.
Medications that generally are good choices for baths are;
* Metronidazole which is s good choice for intestinal infections since it is not readily absorbed through the intestines.
* Kanaplex OR Minocyline for Columnaris, Dropsy.
*Nitrofurazone for Columnaris, Aeromonas or Furunculosis
* Usnea is an experimental alternative that has similar properties to Metronidazole and can also be effective for some viruses and possibly tumors. I use about 1 tablespoon per 6 oz. preparation for a 1 quart bath.
Please see this article for more about Aquarium Medications: “Aquarium Medications/Treatments; How they work”
Dips and similar
For known problems (or sometimes as a preventative for new fish from questionable sources) a 5 minute dip is even more effective (albeit more stressful to the fish). In a dip, I again adjust pH and add Methylene Blue, however in the case of the marine fish, I will use a specific gravity of 1.001 for the saltwater fish and a specific gravity of 1.015 for the freshwater fish. This dip should be no less than 3 minutes and no more than 5 minutes to be effective.
A dip is often a better choice than a bath for a large or otherwise “spastic” fish due to the much shorter duration. As well a dip, albeit much more harsh than a bath (when used as described), may be a better choice for a very ill fish that may be “at deaths door” and the risks of a dip are low when compared to the fact of the probable imminent death of the fish. A dip is also a good choice for problems that stem from fluid build-up and poor osmotic function, such as many causes of “Pop-Eye”.
*Another similar idea is to directly swab, drop, or “paint” with a Q-Tip (or similar implement) Methylene Blue, Potassium Permanganate, or Hydrogen Peroxide onto a problem area such as Saprolegnia/fungus, Columnaris, or similar. This can be VERY effective for stubborn external infected areas on a fish.
Potassium Permanganate & Hydrogen Peroxide are generally more effective for the above noted infections, but extreme care should be exercised that Potassium Permanganate does not get into the gills. A quick bath in water with a 2-3 times dose of Prime or similar water conditioner can help if this were to occur by accident.
A generally safe alternative to strengthen the Methylene Blue swab/paint is to mix equal strengths of Methylene Blue and Maracyn Plus (Sulfamethazine and Trimethoprim), then use this to gently swab onto infected areas of a fish
Product Reference: Maracyn Plus from AAP
For an expanded article about Fish Baths & Dips, please see this article/post from Aquarium Answers:
Fish Baths/Dips -for supplemental (& even primary) treatment of Bacterial infections, wounds, sores, Fungus (Saprolegnia), parasite infestations & more
A FEW HELPFUL CONVERSIONS
(use accurate teaspoons, not silverware):
*Teaspoon = 4.929 mL
*Tablespoon = .5 fl. oz. = 14.787 mL
*For mixing salt for a dip; 1/2 dry cup will make a specific gravity of about 1.023- 1.025; For 1.015 specific gravity for a dip, use approximately 1/3 dry cup.
 Aquarium Sanitation/Sterilization (Using Bleach or Salt);
Without trying to sound too modest, I rarely had outbreaks of even common diseases such as Ich in the 100s of aquariums in my care (discounting my LFS quarantine system), as I was VERY careful to take EVERY step in preventative care which includes the optimum water parameters for the fish kept, regular and PROPER water changes (proper meaning good vacuuming procedures even in “live sand” of reef tanks that many say should not be performed, the key is the correct way), good feeding practices with a varied and healthy diet, and finally the use of properly installed well made level 1 capable UV Sterilizers using HO low pressure UVC lamps (not the cheap UVs sold by many internet retailers for $50 often using 7% output medium pressure UV lamps).
If you have found this site helpful (or the sister site Aquarium and Pond Answers), please consider a donation to help with the 100s of hours of research and regular updates that go into these articles:
| Basic_Aquarium_Principles | Basic_Saltwater | Aquarium_Disease | Aquarium_Lighting | Goldfish_disease | Aquarium_cleaning | Nitrogen_Cycle | Redox_Potential | Clear-Pond | Aquarium_Filtration | Aquarium_Medication | Aquarium UV Sterilization | Vibrio_Aeromonas | Aquarium_Ich | Columnaris | Aquarium-KH | sponge_filtration | Aquarium-Plants | Quality_Fish_Food | Oodinium |
| Return Home | Aquarium_Information | Aquarium Products | Downloads | FAQ | Other | Contact Us | View Cart |