We have recently been posting about the different types of bacteria and parasites that are commonly found in your koi fish.
Here is a combined list of those common illnesses and “diseases” we have posted about, highlighting how you can identify and treat them.
NOTE: Whenever you use chemicals or medications to help combat a particular affliction ALWAYS, ALWAYS use the manufacturer’s recommended dosage. Failure to do so can result in the death of the koi in treatment as well as its pond or tank mates.
Click on the nameto jump to the topic
Aeromonas
Chilodonella
Fish Lice
Ich
Anchor Worms
Columnaris
Costia
Dropsy
Carp Pox
Aeromonas
Type:Bacteria
AKA:Aeromonas hydrophila, Ulcer Disease, Hole In the Side disease
How to Diagnose
- Flashing
- Lethargy
- Loss of appetite
- A small red or white pimple forms on the skin
- A lesion with scales missing
How to Treat
- Quarantine
- Raise water temperatures to 80-82ºF
- Feed Medicated food
- Clean the wound with Hydrogen peroxide
- Add topical antibacterial or inject baytril
- Bathe in tricide-neo
- Raise salinity
Chilodonella
Type: Protozoan parasite
AKA:Lernaea elegans
How to Diagnose
- Need a microscope for proper diagnosis
- Ear- or heart-shaped with cilia (small hairlike structures) on the ventral side
- Fins clamped
- Flashing
- Rubbing
- Gasping at the surface
- Floating on their sides until disturbed
- More time near airstones or waterfalls (increased oxygen areas)
- Increased mucous production
- Skin looks cloudy
- Appetite loss
- Weight loss
How to Treat
- Standard parasite protocols are effective
- Malachite Green and Formalin
- Potassium permanganate bath
- Salt dip (2.5%)
- Salt bath (0.5%)
- Extra aeration
- Smaller doses of food
Fish Lice
Type: Crustacean ectoparasite
AKA:Argulus foliaceus
How to Diagnose
- Visible to the naked eye
- Look for pencil-lead sized, algae-colored, horseshoe-crab shaped creatures
- Rubbing
- Flashing
- lethargy
- Appetite loss
- Red lesions (where the parasite has attached)
How to Treat
- Dab Potassium permanganate on the lice directly
- Carefully remove lice with tweezers
- Use topical antibacterial ointment on open lesions
- Medicated food
- Follow up treatments may be necessary due to egg life cycle and adult-stage hardiness
Ich
Type:Protozoan parasite
AKA:Ichthyophthirius multifilis
How to Diagnose
- Need a microscope for proper diagnosis
- U- or horseshoe-shaped nucleus in a round body
- Flashing (rubbing against the sides or bottom of the pond bottom),
- Lethargy
- Appetite loss
- Small white spots like grains of salt
How to Treat
- Difficult to treat while on the host koi
- Salt solution of 0.3%-0.5% at no more than 80ºF
- Raise salinity slowly to acclimatize fish
- Monitor water temps for salting periods
- 50ºF 14-21 days
- 60ºF from 10-12 days,
- 65-70ºF from 7-8 days
- 75-80ºF 2-5 days
- Try malachite green and formalin if salt is ineffective
- Clean media where possible
- Gradual 30-40% water changes
Anchor Worms
Type:Crustacean parasite
AKA:Lernaea elegans
How to Diagnose
- Visible to the naked eye
- Look like greenish white threads or pieces of floss
- Flashing
- Red, inflamed spots (where the parasite is embedded)
- Ulcerations on the skin
- Difficulty breathing
- Lethargy
- Loss of appetite
How to Treat
- Standard parasite protocols are most effective
- Potassium permanganate—either as a dip in a quarantine tank or entire pond (5-10ppm)
- Dimilin
- Formalin (exercise caution if it has open wounds, though)
- Salt dip (to lessen secondary infection)
- Anchor worms can be removed with tweezers
- Grab them as close to the entry point as possible
- Make sure that the entire parasite is pulled
- Disinfect the wound afterwards (to minimize infection)
- Only keep the koi out of the water for a few seconds at a stretch (and especially if it is already stressed)
- Removal may cause more stress and trauma than leaving it in, so treating them chemically can be a better alternative
Columnaris
Type:Bacteria
AKA:Cottonmouth, Fin Rot, Tail Rot, Saddleback disease, Flavobacterium columnare
How to Diagnose
- The fins and tail look ragged
- Sores or lesions will develop on the body, eventually becoming ulcers
- A lesion around the dorsal fin is common, banding around the fish
- Koi develops a white milky sheen in patches over the body
- Discolored mucous around the mouth, eyes and on the head and dorsal regions.
- Gills will become a discolored, brown color
- Breathing shallowly and rapidly
- Lethargy
- Appetite and weight loss
- Lot of time near the surface
- Resting for long periods on the pond/tank bottom
How to Treat
- Quarantine immediately
- Lower the tank temperature to reduce virulence
- Start with 0.5% solution salt bath
- 30-50% water change to reduce risk of spreading rapidly through the water column
- Clean the pond floor media to remove as much waste as possible
- Potassium Permanganate bath is the most common treatment
- Treating external infections with hydrogen peroxide
- Use Nitrofuran-based antibiotics (like Nitrofurazone or Furazolidone)
- Feed koi antibiotic medicated foods
- Finish the course to limit chance for future resistance
- Clean all tanks thoroughly
Costia
Type:Flagellate protozoan parasite
AKA:Ichthyobodo necatrix
How to Diagnose
- Need a microscope for proper diagnosis
- Look for fast-moving, kidney-shaped body with two flagella
- Loss of appetite
- Lethargy (long periods of not moving)
- Fin clamping
- Labored (or “heavy”) breathing
- Rubbing
- Red lesions with white slime
- Increased slime production (which appears blue-grey in color)
- Mucous coming out of the gills
How to Treat
- Start with single Potassium Permanganate treatment
- should not be used if there is gill damage
- turn off UV light (where applicable)
- Salt treatment (either in a separate bath or as a long-term pond treatment)
- 3% Hydrogen peroxide on the open lesions to slow its growth
- Single dose of anti-parasite treatments (like malachite green and formalin)
- Raise the water temperature to the low 90ºF range
Dropsy
Type:Multifaceted causes (viral, parasitic bacterial, congenital), but damage mostly due to bacterial infection
AKA:Pinecone, Bloater disease, Pop-eye disease
How to Diagnose
- Eyes bulging out
- Distended (bloated) stomach
- Raised scales (so it looks like a pine cone
- Gasping
- Unbalanced swimming (as the swim bladder is affected by the excess fluid, too)
- Appetite loss
- Once these physical symptoms are noticeable, it is usually too late
How to Treat
- Act quickly
- Isolate affected koi
- Raise water temps
- Increase oxygenation
- Adopt antibacterial regimen
- Antibiotic regimen may include tetracycline, naladixic acid, penicillin or baytril
- Use antibiotics (either injected or in feed)
Carp Pox![How to Recognize and Treat Common Koi Fish Illnesses (9) How to Recognize and Treat Common Koi Fish Illnesses (9)](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)
Type:Virus
AKA:Cyprinid Herpesvirus 1
How to Diagnose:
- White, grey, blue or pinkish spots that look like molten wax
- Look for spots on head, shoulders and fins (sometimes they will cover the whole body)
How to Treat
- As a virus, and without an effective antiviral option, prevention of an outbreak is the best treatment
- Reduce potential stressors:
- lower your fish load
- optimal water parameters
- high dissolved oxygen levels
- be vigilant of ammonia
- monitor pH closely
- Periodic Chloramine T dosing (reduces opportunistic pathogen instance)