Iridovirus in Gouramis

Iridovirus in Gouramis
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.

For the full article (including management & summary) please follow click here:
EDIS; 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.

Koi Pox; herpes virus

Koi Pox; herpes virus.
From the full article: Koi Herpes Virus (KHV) Disease

Introduction;

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.

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).

For the full article (including treatment) please follow click here:
Koi Herpes Virus (KHV) Disease

UV Sterilization

From the Article “UV Sterilization”

I am using this article for the first article digest as this seems to be an area of aquarium/pond keeping with much misunderstanding or even blatant misinformation.

Overview
Ultra violet sterilization is one of the most effective means of disease prevention in aquariums and ponds and for general water quality control in aquariums and ponds, which is part of where a properly installed UV Sterilizer helps provide improves a fish’ chances in fighting diseases such as ich that UV Sterilization is less effective directly in destroying. Part of the reason for UV Sterilization (which is often missed) is that the UVC radiation 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 only focus on the germicidal/algaecidal properties of UV Sterilizers. Please read this article for more about this subject: “Fish Immune System and UV Sterilization”.

Benefits
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 (although at times I may have too). I am also constantly researching this subject, so this article may not be the same article in three months, so please read on.

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”)

UVs are also useful in Reef aquaria, especially new ones where the chance of disease introduction is high and the UVs help in keeping a balanced Redox Potential is useful. As the reef aquaria ages the sterilizer can be placed on a timer or turned on and off as needed.

As for the Redox Balance, this is an often overlooked aspect of both freshwater and saltwater aquarists. 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,
For more information about the Redox Potential:
Aquarium Redox Balance

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).
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. Also this is great for 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 have dealt with in the 100s of aquariums I have serviced.

Maintenance
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)

For the full in depth article “UV Sterilization”