Tag Archives: sick fish


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



Koi Pox; herpes virus.


Koi herpes virus (KHV), a viral disease highly contagious to fish, may cause significant morbidity (sickness or disease) and mortality in common carp (Cyprinus carpio) (Hedrick et al., 2000; OATA, 2001). This species is raised as a food fish in many countries and has been selectively bred for the ornamental fish industry, where it is known as koi. Historically, the first outbreak of KHV was reported in 1998 and confirmed in 1999 in Israel.
Since then, other cases have been confirmed in the United States, Europe and Asia (Hedrick et al., 2000; OATA, 2001; Anonymous, 2003). This information sheet is intended to inform veterinarians, biologists, culturists, and hobbyists about KHV.

What Is KHV?
KHV is currently classified as a DNA-virus belonging to the virus family Herpesviridae (i.e., a herpes virus). Although there has been some scientific discussion regarding the accuracy of this classification (Ronen et al., 2003), more recent work (Waltzek et al., 2004) shows strong evidence that KHV is indeed a herpesvirus, based on morphology and genetics. KHV disease has been diagnosed in koi and food fish carp (Hedrick et al., 2000; OATA, 2001). Other related cyprinid species such as the common goldfish (Carassius auratus) and grass carp (Ctenopharyngodon idella) seem to be unaffected by KHV. As with other herpes viral infections, KHV is believed to remain in the infected fish for life, thus exposed or recovered fish should be considered as potential carriers of the virus (OATA, 2001).
KHV disease may cause 80-100% mortality in affected populations, and fish seem most susceptible at water temperatures of 72-81°F (22-27°C) (OATA, 2001). This viral disease affects fish of various ages, but cohabitation studies show that fry have a greater susceptibility than mature fish (Perelberg et al., 2003).

What Are the Signs of KHV?
Clinical signs of KHV are often non-specific. Onset of mortality may occur very rapidly in affected populations, with deaths starting within 24-48 hours after the onset of clinical signs. In experimental studies, 82% of fish exposed to the virus at a water temperature of 22°C died within 15 days (Ronen et al., 2003). KHV infection may produce severe gill lesions and high mortality rates. In some cases, secondary bacterial and parasitic infections may be the most obvious problem, masking the damage caused by the primary viral infection. Behaviorally, affected fish often remain near the surface, swim lethargically, and may exhibit respiratory distress and uncoordinated swimming.

Koi Pox External signs of KHV may include gill mottling with red and white patches (see picture) (similar to Columnaris disease), bleeding gills, sunken eyes, pale patches or blisters on the skin. Microscopic examination of gill biopsies often reveals high numbers of bacteria and various parasites (Hedrick et al., 2000; OATA, 2001; Goodwin, 2003).
Internal signs of KHV are inconsistent and non-specific, but they may include adhesions in the body cavity and a mottled appearance of internal organs (Hedrick et al., 2000; Goodwin, 2003).

How Do Fish Get Infected with KHV?
The herpes virus that is responsible for KHV seems to spread in the same ways as most herpes viruses. Methods of transmission include direct contact with infected fish, with fluids from infected fish, and/or with water or mud from infected systems. Depending upon water temperature, fish that are exposed and susceptible may become infected and either develop the disease and die or become carriers of the virus (OATA, 2001). Goldfish and other fish in the carp family are not susceptible to KHV disease, and they do not appear to act as carriers of the virus (Perelberg et al., 2003; Ronen et al., 2003).

Level One UV Sterilization is very effective against this virus and although not a treatment for infected fish, a properly installed/quality UV Sterilizer should be employed for prevention.
If your pond (or aquarium) already has a UV Sterilizer, it is also imperative to change your UV Bulbs every six months for level one UV Sterilization maximum effectiveness.


*Pond Care Information
An easy to follow article about pond care with many more in depth resources as well as product resources cited

*Aquarium Lighting Information
An in depth article that I recommend and have found to be the most up to date anywhere. It includes information about the many types of lights including LED Aquarium Lights.

*Aquarium Chemistry
Probably the best article on the subject of aquarium chemistry I have found. The author gets it right with the science behind electrolytes, GH, KH and more

Copyright 2019, By Steve Allen