Tag Archives: Redox


Iridovirus in Gouramis

Further Revised 1/8/19

From the full article: “EDIS; Iridovirus in Gouramis”
By RuthEllen Klinger, Ruth Francis-Floyd, John Slaughter and Craig Watson

What Are Iridoviruses?

Iridoviruses are a family of viruses (130–300 nanometers in size) that contain DNA as their genetic material and have an icosahedral (20-sided) capsid. Iridoviruses have been found in a wide variety of fish, including both freshwater and saltwater species.
Some iridoviruses have been associated with serious diseases (e.g., viral erythrocytic necrosis of salmonids) while others have only been found in apparently healthy animals (e.g., goldfish iridovirus).
One iridovirus causes a disease called lymphocystis which causes unsightly skin lesions on infected fish, but otherwise is of little consequence.

Iridovirus in Gouramis

An iridovirus was found in spleen and intestinal tissue of gouramis from the genus Trichogaster that were dying with signs of systemic disease. Mortality rates of affected fish have varied from low (0.5–10%) to moderate (50%) with death usually occurring 24–48 hours after the onset of signs. Clinical signs associated with the presence of the iridovirus have included darkening of body coloration and lethargy. Sick gouramis often stop eating and the abdomen may be distended. Internally, an enlarged spleen has been the most notable abnormality. The intestine may be reddened, and a clear amber fluid may be present in the body cavity. Laboratory examination for bacterial, fungal, or parasitic agents has frequently been negative. Through electron microscopy (EM), abundant iridoviral particles have been found in the spleens and intestines of dying fish.

An iridovirus has been isolated in cell culture and cytopathic effect (death of infected cells) has been observed. Although the iridovirus has been implicated as a possible cause of disease in gouramis, efforts to reproduce the disease under laboratory conditions have not yet been successful.

The picture below shows a Dwarf Gourami displaying symptoms that are sometimes found with DGIV (Dwarf Gourami Iridovirus). Often darkening of the body is also a classic symptom too.

Iridovirus in Dward Gourami, DGIV

Very little can be done for a fish with Iridovirus, often euthanasia is the best course of action.
Treatments to consider would be a Medicated Fish Bath along with a Medicated Wonder Shell in tank.
*Fish Baths, Dips, Swabs
*AAP Wonder Shells; Regular & Medicated. The ONLY Authorized online seller

Level One UV Sterilization can also help with prevention both by killing any viruses outright that pass through the ‘Category A’ UV Sterilizer and by improving Redox Balance.
Proper flow rate, installation, even the correct UV (as many now sold are junk), and proper maintenance (which includes changing the UV Bulb) are essential this tool being effective for prevention of Iridovirus in Gouramis.

Further reference:
RuthEllen Klinger, Biological Scientist, Fisheries and Aquatic Sciences; Ruth Francis-Floyd, Associate Professor, Fisheries and Aquatic Sciences; John Slaughter, Veterinarian, Hillsborough County Extension Service; Craig Watson, County Extension Agent, Hillsborough County Extension Service; Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.


*A Healthy Aquarium, Disease Prevention
An excellent step by step scientifically tested method to keep more disease free fish in an aquarium (or pond)

*Columnaris; As well as Fungus in Aquarium Fish
The Internet’s premier article on the subject of Columnaris. By far the most in depth and research/experience based article on the subject.

*How Aquarium or Pond Fish Medications Work
A very in depth article, divided into 4 total web pages

*Aquarium Lighting Facts & Information
In my experience, this is by far the best and most accurate article on the subject. Any obvious biases are well backed up by factual research.
It includes information about the growing in popularity LED Aquarium Lights.

Copyright 2019, By Steve Allen



Copyright 2014, By Steve A
Revised 10-18-19

I am using this article for the first “aquarium article digest” entry as this seems to be an area of aquarium/pond keeping with MUCH misunderstanding, and even as of the most recent revisions, continues to be if not more so than when I first wrote this article in 2009.

Ultra violet ‘C’ sterilization is a process that is one of the most effective means of disease prevention in aquariums and ponds and for general water quality control in aquariums and ponds.
A correctly installed, quality UV Sterilizer helps provide and improve a fish’ chances in fighting difficult diseases such as ich even though UV Sterilization is less effective directly in destroying this disease pathogen.
See this example of an online seller of good to premium quality Sterilizers: Aquarium & Pond UV Sterilizer

Aquarium UV Sterilizer Clears OxidizerPart of the reason for aid in fish immunity, is that UV Sterilization is that the UVC irradiation which is contained in the unit will break down oxidizers in the water column that would otherwise lower a fish’ immunity (Redox Balance), this aspect is often missed as many persons use only focus on the germicidal/algacidal properties of UV Sterilizers.

This not only has been proven in controlled tests by gurus in aquarium research such as Carl Strohmeyer, it is easy to demonstrate by adding an oxidizer such as Potassium Permanganate that colors the water and running a level one UV sterilizer against a control aquarium with none (all parameters, bio load, etc. otherwise equal) and noting the considerable speed the Potassium Permanganate is cleared from the aquarium utilizing the UV Sterilizer.

The photo to the above/right demonstrates this.
Credit: Aquarium & Pond UV Sterilization | How to use a UVC Sterilizer

Further Reference: Aquarium Redox Balance

Please read this article for more about this subject:
“Fish Immune System and UV Sterilization”.

Unfortunately many aquarium/pond forums also focus only on the aspect of irradiation of disease (which can be hit or miss depending upon installation and UV quality), but miss the aid UV Sterilizer provide in improving Redox balance.
Many of my friends in the professional aquarium & pond maintenance business have cited many times that a new customer would call them out for help complaining the UV Sterilizer they purchased elsewhere was useless, but after investigating these professionals would find that the UV was of poor quality and/or incorrectly installed.

This has been especially common of late with the influx of low quality UVs such as the Green Killing Machine, Submariner, Jebo, AquaTop, and many others which is what you get for under $50 on eBay or Amazon, as well as some of the many low end online retailers.

The unfortunate aspect of purchasing these low end UV Sterilizer is that these are not really sterilizers at all, rather just clarifiers.

So what often happens is a person purchases one of the cheap UV units, then sees no improvement in fish health, then goes onto some aquarium forum, Facebook, Youtube, Yahoo Answers, etc. and reports that the device was useless.
The problem is the devise they purchased was useless for true level one UV Sterilization, but the process and the concept is not.
This very common problem is analogous to purchasing a thin plastic tarp to cover ones swimming pool and then when a child still falls in, stating pool covers are junk, when in fact a pool cover designed for protecting children from the pool should have been used and would have worked!!
Example: http://www.poolcoversinc.com/benefits.shtml

Excellent video on the subject:
Do I really need a uv sterilizer
Do I Really Need UVC?

What are we looking for to properly utilize UVC energy for irradiation?

  • Water flow rate through the UV Sterilizer. This is often expressed as “gallons per hour” or gph per watt of UVC energy
  • Dwell time (related to flow rate). This is the time the water stays inside the UVC irradiation chamber
  • An actual High Output (HO) low pressure UV Lamp/Bulb. The difference between the more commonly used medium pressure UV lamps is as much as FOUR TIMES the UVC output. Even in a less expensive Chinese built UV Sterilizer this can mean the difference between a TRUE UV Sterilizer and a UV Clarifier.
    Most sold via Amazon and other discounters DO NOT utilize HO UV lamps.
    Further Reading: Actual UV-C Emission from a UV Bulb; Aquarium or Pond
  • Water Turnover in pond or aquarium per hour. This is how many times per hour the water is passed through the UV Sterilizer as per a given unit of water in the aquarium or pond
  • Distance of UV Lamp from UV Sterilizer containment ‘wall’. This should be no more than 3 mm, which many “built in” canister aquarium or pressurized pond UVs are much greater than.
  • Temperature of water. UVC is effective is between 20 C (68 F) and 40 C (104 F)
  • Pre-Filtration including Turbidity of water. Particulates in the water can & do have a affect the ability of the UVC to damage or destroy pathogen, algae, or reduce oxidizers (Redox)


There is a lot of new evidence as to the benefits of UV sterilization for ALL fish, and many myths have been dispelled such as “UV Sterilizers destroying beneficial nitrifying bacteria”.
I will try and present material in as readable a format as possible, rather than get down to too much scientific jargon that is difficult for many to understand as many facts can often be presented without every technical term applied.

UV Sterilization is also effective for controlling suspended algae (green water) in ponds, along with proper filtration such as Veggie Filters/pressurize filters, please see this article:
“A Clear Pond; pond information”.

True Level One UVs are also useful in Reef aquaria, especially new ones where the chance of disease introduction is high, as well the UVs help in keeping a balanced Redox Potential which is useful for disease prevention via boosting the fish’ own immune response.
As the reef aquaria ages the sterilizer can be placed on a timer or turned on and off as needed (although I still recommend running 24/7 in many reef aquariums).

As for the Redox Balance, this is an often overlooked aspect of both freshwater and saltwater aquarists that HAS BEEN PROVEN in well funded studies to aid in immune response.
Unfortunately some aquarium forums choose to ignore this science or push low end UVs (often under $50) that cannot product level 1 UVC

The Redox Balance is basically the oxidation and reduction properties of water.
This is VERY important for proper breakdown of organic waste (the oxidation side of Redox)! Especially in aquariums where the fish/invertebrates come from waters of low turbidity (African Cichlids) or tend to produce a lot of waste (Goldfish).
“Most experts now agree that the Redox should be +300 to -100 mV for marine or +125 to -200 mV for freshwater for healthy fish immunity, which a UV Sterilizer can help maintain.”
Used with permission From: “Aquarium & Pond UV Sterilization

For more information about the Redox Potential, please reference:
Aquarium Redox Balance

Further Reference: UV Therapy

Anecdotal Arguments Against

One argument against UV Sterilizers in ponds is that they are not natural, but for the clarity most persons want out of their pond, this is not possible without either UV sterilization or a flow thru stream (although many persons with well planted, well shaded ponds do well with clarity too, but UV Sterilization further compliments these ponds too).

Many articles I have read state that a UV is not that beneficial to an established aquarium as a healthy aquarium depends on beneficial bacteria typically growing on media in your filter which neutralize ammonia.
Unfortunately the problem with this statement is beneficial bacteria belongs in the filter, not in the open water column which is all a UV Sterilizer effects.
Also this may work well for some advanced aquarists who are not adding fish and have a healthy Redox Potential/Balance, but not in the real world of average and above average aquarists that I and many of my friends have dealt with in the 100s of aquariums they have serviced.

Also it is noteworthy that an aquarium is a closed system, NOT OPEN, so inputs of added buffers, minerals, Redox reducers, etc are necessary.
The use of level 1 UVC irradiation is just one more of these inputs since Redox Balance has been scientifically proven to improve with the use of level 1 UVC.
The problem is often these persons stating they used a UV Sterilizer with no improvement in fish health, were likely not setting up the UV correctly or more likely, were using one of the many cheap UVs flooding the market such as the JBJ, AquaTop, Green Killing Machine from sellers such as Amazon.

Some Recommended Aquarium UV Sterilizers

  • AAP/TMC Vecton & Advantage Level 1 & 2 Capable UV Sterilizer
    There are simply NO BETTER UVs than these. TMC made a name for themselves with these decades ago and are still the best value (yes Aqua Ultraviolet & Emperor are also good, but these still fall short in dwell time and value
  • AAP Terminator UV Sterilizers
    While an economy UV sold under many names, these have a HO UVC Lamp that most other Economy UVs do not
  • AAP Submersible/Internal UV Pump/Filters
    While this style is not as efficient nor as long lived, it is very user friendly. Once again the AAP models is different than most in that it utilizes a HO UVC lamp along with adequate Pre-filtration that most others do not

Aqua UV versus TMC UV Sterilizer
Aqua Pond UV vs TMC AAP Pond UV Clarifier Sterilizer


UV Sterilizer maintenance is quite straight forward; make sure you keep your unit dry on the outside, if used for a pond try and protect your unit from harsh weather (most sterilizer can withstand the outdoor environment, they just last long if they can at least be partially sheltered).

Change your UV bulb every 6 months for aquariums, and also every 6 months for ponds in warm climates where there is no winter freeze.
In cool climates a pond UV bulb can be changed every season (usually late spring/ early summer).
See: High Output UVC Replacement Lamps

For a full in depth article on this subject:

How UV Sterilization Works, For True Level 1 or 2 in Aquarium/Pond

The above article should be read for much better understanding of how to correctly use your UV Sterilizer.

Unfortunately with the Google Search of late mostly becoming a Spam search for about.com (not “the spruce”), Amazon.com and others; GOOD RESEARCHED articles such as the one above are more difficult to find, but I urge my readers to read this article in full, then read it again (and maybe again until you understand the concepts presented!!
Do NOT purchase a UV Sterilizer UNTIL you read the above article

If you do decide to purchase a decent UV, not just some cheap toy calling itself a UV Sterilizer, consider this website that a professional in the industry I know with 3.5 decades of experience in UV Sterilization owns:
Good to Premium UV Sterilizers for Aquarium or Pond


*Aquarium Lighting
An in depth article that I have found to be the most accurate and up to date anywhere. It includes information about the growing in popularity LED Aquarium Lights.

*A Healthy Aquarium, Disease Prevention
An excellent step by step scientifically tested/proven method to keep a more disease free aquarium

*Aquarium Ich: Ichthyophthirius Multifilis and Cryptocaryon Irritans

*FISH COLUMNARIS | Fungus & Saprolegnia | Treatment & Prevention

*Pond Algae

*Pond Care, Information

Copyright 2019, By Steve Allen