Yellow Fungus in Reptiles
Reptile Health Guides · Conditions
Bearded Dragon Yellow Fungus (CANV): Signs, Spread & What To Do Tonight
If you are reading about bearded dragon yellow fungus, a reptile-experienced veterinarian is the best first step. This guide explains what owners commonly see and what to do next. It does not diagnose or prescribe.
Bearded dragon yellow fungus is a serious, contagious fungal skin infection. It is caused by fungi in the Nannizziopsis group, and you may also see it called CANV. The infection starts in the skin but can spread deep into muscle and organs.
It is often mistaken for stuck shed at first. Because it spreads easily between reptiles and can be fatal, any crusty yellow or brown patch that does not shed normally needs a vet.
Important: Yellow fungus needs a vet diagnosis and a long course of prescription antifungal treatment. Do not try to treat it with creams or soaks alone, and keep the affected reptile away from others.
What Yellow Fungus Is
A Contagious Fungal Infection
Nannizziopsis fungi infect the outer skin and can invade deeper tissue. Bearded dragons are most often affected, but other lizards can be too.
Why It Is Serious
Without treatment, the infection can spread through the body. Even with treatment, it takes weeks to months to clear.
How Vets Confirm It
Your vet usually takes a skin sample or biopsy and sends it for culture or testing, because other skin problems can look similar.
How Owners Spot Yellow Fungus
Yellow or Brown Crusts
Raised, crusty, yellow, tan, or brown patches that look like stuck shed but do not come off.
Thickened or Darkened Scales
Scales that thicken, darken, or turn grey-black, often on the head, limbs, or sides.
Sores Under the Crusts
When crusts fall off they can leave raw, open sores.
Weight Loss and Lethargy
In advanced cases, appetite drops and the dragon loses weight and energy.
How Yellow Fungus Spreads
Direct Contact
Reptiles housed together, or sharing basking spots, pass it on through skin contact.
Shared Equipment and Hands
Fungal spores survive on décor, substrate, enclosures, and hands. Wash hands and disinfect tools between reptiles.
Stress and Weak Immunity
Poor husbandry, other illness, and stress make infection more likely and more severe.
How Vets Treat Yellow Fungus
Prescription Antifungals
Treatment usually means weeks to months of a prescription antifungal by mouth, often with topical treatment. Doses are set by your vet and need follow-up.
Supportive Care
Many dragons need fluids and nutrition support during treatment. See reptile supportive care.
Enclosure Disinfection
Your vet will advise on cleaning. Porous items like wood and cork are hard to disinfect and are often thrown away.
What To Do Tonight
Early
One or two small crusty patches that do not shed: isolate tonight and see a reptile vet within days. Early treatment works best.
Severe / urgent
Spreading patches, open sores, weight loss, or lethargy: see a reptile vet promptly.
Related products
Supplement listing. Follow the label, and check with your reptile vet first for a sick, gravid, very young, or underweight reptile.
View product →Free shipping on orders $75+. Prices and stock update automatically. Products are listed for education; medicines are used only when a veterinarian directs care. This page does not diagnose or prescribe.
Related Reptile Health Guides
Back to Reptile Health Guides →Yellow Fungus in Reptiles FAQ
What does yellow fungus look like on a bearded dragon?
Raised, crusty yellow, tan, or brown patches that look like stuck shed but do not come off, sometimes turning darker or leaving sores.
Is yellow fungus contagious?
Yes. It spreads through contact and on shared equipment and hands, so affected reptiles must be isolated.
Can yellow fungus be cured?
Many dragons recover with early, long-term vet treatment, but advanced cases can be fatal. Starting treatment early gives the best chance.
Is CANV the same as yellow fungus?
Yes. CANV is an older name; the fungi are now grouped as Nannizziopsis. Both names refer to the same disease in bearded dragons.
Can antibiotics like Baytril treat yellow fungus?
No. Antibiotics treat bacteria, not fungus. Your vet may still use one if sores become infected with bacteria.
Is this Yellow Fungus in Reptiles guide a substitute for a vet visit?
No. It is educational only. A veterinarian experienced with reptiles should guide diagnosis and any treatment.
Can I work out a medication dose from this page?
No. Never work out doses from product strengths or internet pages. Reptile doses depend on the species, weight, temperature, and health of the individual animal, so they must come from your veterinarian.