VIRAL INFECTIONS


An upclose shot of VHS, or Viral Hemorrhagic Septicemia, a very fatal and contagious disease in freshwater aquaria.

VIRAL HEMORRHAGIC SEPTICEMIA (VHS/VHSV/Egtved Disease/Egtved Virus/Red Pest):

Usually FATAL within 4-6 days. Highly Contagious. ISOLATION REQUIRED. Fish who are successfully treated are capable of carrying the viral infection and spreading it for the rest of their lives and should remain either with other surviving fish or on their own to avoid the further spread and development.

May or May Not Show Symptoms

  • Viral Bloodstream Infection. The virus is spread through the urine, feces, and reproductive fluids (ovarian fluids or sperm).
  • The virus may enter a fish’s system through the gills, open wounds, and digestive tract.
  • Incubation period lasts 1-2 weeks in warmer water and 3-4 in cooler water.
  • Replication of the virus is most efficient at 14-15 degrees celsius, or 52.7-59 degrees fahrenheit, and a pH between 7.4-7.8 ppm. Above 68 degrees fahrenheit (20 degrees celsius), reproduction of the virus itself becomes inactive and it depends on the spread from fish to fish.
  • Red streaks under scales
  • Open Wounds and Ulcers
  • Hemorrhages in muscle or organ tissues, on body, eyes, gills, base of fins
  • Fluid Retention in Abdominal Region
  • Darkened Coloration
  • Abnormal Swimming Behavior
  • Popeye can occur as secondary infection
  • Lethargic, Clamped Fins
  • Fish may become hyperactive, show erratic swimming. It may twist it’s body, make corkscrew movement, circles.
  • Internal hemorrhages can be found in the heart, swim bladder, kidneys, or liver.
  • Liver and Kidney abnormalities may form
  • Bleeding in the organs may develop.
  • VHS originates from the family Rhabdoviridae , which includes the rabies virus.

CAUSES:

  • Direct contact with infected fish, body fluids, feces, water, or even contaminated equipment.
  • Injury makes a fish more likely to become infected
  • Consumption of an Infected Tankmate
  • Stress
  • Poor Water Quality

TREATMENT:

  • 25% Daily changes
  • UV filtration devices will kill the virus
  • Medicate (Kanaplex, Maracyn, Maracyn-Two, Jungle Antibacterial Fish Food)
  • Clean all equipment. sodium hypochlorite (bleach), 10% chlorine, and iodophor (iodine solutions) are effective in treating decorations, tank interiors, and equipment.
  • Quarantine new and ill fish, isolate surviving fish.

VIRAL LYMPHOCYSTIS (Lymphocystivirus/Lymphocystis disease virus/LCDV) :

  • Common viral infection
  • Chronic
  • Member of the Iridoviridae family.
  • Cream or grey colored pebble or wart-like nodules may appear on the fins, skin, and gills (most commonly).
  • Potentially FATAL in heavily infected fish
  • catfish (Order Siluriformes), cyprinids (goldfish, koi, barbs, or danios; Family Cyprinidae) and salmonids (Family Salmonidae) are not known to be affected by this virus
  • Popeye may develop as secondary illness, or lymphocystis masses may develop behind the eye and push it out of the socket.
  • Swimming and breathing problems may be affected
  • Some organs such as the spleen may be affected by this virus
  • In early stages, this is easy to misidentify as ich, white grubs, skin cancers, fungus clumps, Epistylis (a stalked, ciliated, protistan parasite), or even epitheliocystis (an intracellular bacterial disease).

CAUSES:

  • Direct contact with contaminated equipment or other fish
  • Open wounds make a fish more likely to succumb to this
  • Overcrowding and other stress factors are also causes
  • Lymphocystis disease virus 1 (LCDV-1) contamination.

TREATMENT:

  • Usually Self Resolved. No Known Efficient Treatment.
  • Maintain proper social group sizes, water quality, proper diet, etc for optimal fish health.

Cleaning Equipment to Prevent the Spread:

  • Multiple methods have been proven effective to treat equipment after contact with infected fish or water:
    • 15 minutes at 77°F (25°C)
    • potassium permanganate (100 mg/L or higher)
    • formalin (2000 mg/L or higher)
    • sodium hypochlorite (liquid bleach—various formulations) at 200 mg/L or higher
    • Be sure to use proper precautions (adequate ventilation and personal protective equipment) when handling chemicals.
    • May also be inactivated by raising the pH to 11 or greater for 30 minutes or more with high temperatures (122°F [50°C] minimum for 30+ min).

HERPES VIRUS IN FISH:

The following information is about all the herpes viruses which could be found in a home aquarium or pond. Not all known herpes viruses known to affect fish or animals are listed here, only the ones that may make their way to pet fish or ornamental fish. While there are many types of herpes viruses, the following mainly pertain to carp and carp hybrids but can spread to almost every other species of fish which contracts in, channel catfish, and black bullhead catfish. While not all fish are the main hosts of these, related species may still be able to contract it. The majority of these diseases have a lack of information regarding treatment and and even symptoms, making it difficult to gather more accurate information for varying sources.

Note: Based on research, IcHV-1 and IcHV-2 (not included due to lack of available information) don’t have any mentioned hosts which might be in the average home aquarium. IcHV-1 has been included because some aquarists will maintain species such as channel catfish, and there isn’t enough research to say if it can be contracted to other, more common species which are related or similar to channel catfish or black bullhead catfish.

This chart is from Herpesviruses of Fish, Amphibians and Invertebrates. http://cdn.intechopen.com/pdfs/31266/InTech-Herpesviruses_of_fish_amphibians_and_invertebrates.pdf). See References for full citation


CYPRINID HERPESVIRUS-1 (CyHV-1/Carp Pox/Fish Pox/Papilloma Virus):

  • Also called: epidermal hyperplasia; epidermal proliferation; epithelioma papulosum; epithelioma papulosum cyprini; herpesviral epidermal proliferation in carp; herpesvirus septicaemia in carp; papillomatous skin growth
  • Lesions may develop across the body, but are more notably seen at the base of fins.
    • These lesions may flat, firm, smooth and translucent at first. They will grow larger with time.
  • Enlargement of scales may occur all over the body
  • Milky to greyish white soft growths may occur which are several centimeters long and 4-6mm thick. They may appear to have a wart covered surface as well. Potentially pink tinted.
  • Emaciation
  • Growth Stunting
  • Rubber Bones may develop (similar to MBD) which may cause deformed spines.
  • Lack of information regarding treatment. Not much information is known about it

Internal Identification Factors:

        • Necrosis of liver, kidney, and intestinal mucosa

CAUSES:

  • Viral infection caused by CyHV-1 from the family Alloherpesviridae

TREATMENT:

  • Maintain proper water quality and diet
  • If rubber bones develop, incorporate more, easily absorbed, sources of calcium to the diet. DO NOT OVERDO.

CYPRINID HERPESVIRUS-2 (CyHV-2/GHV/Goldfish Haematopoietic Necrosis Virus/Herpesviral hematopoietic necrosis virus/HVHN):

  • Anemia
  • Pale Head and Gills
  • Patchy gill necrosis
  • Loss of skin mucus
  • Lack of information regarding clinical symptoms.

CAUSES:

  • Viral infection caused by CyHV-2 from the family Alloherpesviridae

TREATMENT:

  • Elevate temperatures into the 80’s (Farenheit)
  • Lack of information regarding treatment. Not much information is known about it

CYPRINID HERPESVIRUS-3 (CyHV-3/Koi Herpesvirus Disease/KHV/KHVD/Carp Interstitial Nephritis/Gill Necrosis Virus):

  • FATAL. NO TREATMENT. HIGHLY CONTAGIOUS. ISOLATION REQUIRED.
  • Only affects fish between 64.4 degrees fahrenheit and 82.4 degrees.
  • Effects all common carp (Cyprinus carpio) and all ornamental varieties such as koi and all carp hybrids.
  • Pale, discolored skin and gills and rough, sandpaper-like skin texture
  • Focal or total loss of epidermis and irregular skin patches with skin blistering
  • Over and underproduction of slime coat covering skin and gills
  • Enopthalmia (sunken eyes)
  • Hemorrhages at base of fins and skin, skin and fin erosion possible
  • Lethargic and/or anorexic. Fish may isolate themselves. Hyperactivity and erratic swimming are also possible. Loss of balance.
  • Fish may lie on the bottom of the tank, inactive, with the dorsal fin folded
  • Necrosis of the gills may be visible
  • Gasping for air
  • Similar to Epizootic ulcerative syndrome and spring viraemia of carp

Internal Identification Factors:

        • adhesions in the abdominal cavity with or without abnormal colouration of internal organs (lighter or darker)
        • kidney or liver may be enlarged, and they may also exhibit petechial haemorrhages
        • Inflammation and necrosis of gill tissue adhesion of gill filaments
        • nuclear swelling, margination of chromatin and pale eosinophilic intranuclear inclusions of the epithelium
        • non-specific inflammation and necrosis in other organs.

CAUSES:

  • Viral infection caused by CyHV-3 from the family Alloherpesviridae
  • Direct fish to fish contact with infected fish and infected water
  • The virus is shed through feces, urine, as well as gill and skin mucus.
  • Occurs between 60.8 degrees Fahrenheit and 77 degrees fahrenheit.
  • Skin abrasions offer susceptibility.
  • Virus enters fish via the skin and gills, as well as orally through infected food or consumption of deceased host.

Control:

  • If possible, raise temperature to or above 82.4 degrees Fahrenheit
    • The virus’ course will run for longer in cooler temperatures ( < 73.4 degrees Fahrenheit)
  • For disinfecting eggs: iodophor at 200 mg litre–1 for 30 seconds at 59 degrees Fahrenheit (15°C)

ICTALURID HERPESVIRUS-1 (IcHV-1/CCV/CCVD/Channel Catfish Virus):

Easy to misidentify as Enteric Septicemia of Catfish (ESC)

  • Potentially FATAL and HIGHLY CONTAGIOUS.. Survivors of the infection are still capable of carrying and spreading the disease, and must be ISOLATED. UNTREATABLE.
  • Only reported in Channel catfish, closely related blue catfish, and channel catfish hybrids.
  • Bloated, fluid filled abdomen
  • May develop with a columnaris infection
  • Spiral movements in water
  • Exophthalmos may occur
  • Swimming in a vertical position

Internal Identification Factors:

        • yellow ascites, swollen spleen and posterior kidney.
        • edema of the liver and gastrointestinal tract
        • necrosis of pancreatic tissue
        • congested spleen

CAUSES:

  • Direct fish to fish contact or contact with infected water where virus is present and active.
  • Viral infection caused by IcHV-1 from the family Alloherpesviridae

Control:

  • Isolate infected fish and maintain in their own tanks. DO NOT CROSS CONTAMINATE.
  • UNTREATABLE.
  • UV Filters can deactivate the virus in an aquarium’s system