Candida albicans overgrowth in the crop — also called sour crop or thrush — is a common upper digestive infection in cockatiels, especially hand-fed chicks and adults on poor diets or recent antibiotics. Affected birds regurgitate slow-emptying crop contents that smell sour, lose weight, and develop white plaques inside the mouth. Nystatin or fluconazole resolves most cases within 7 to 14 days when paired with husbandry correction (AAV Basic Care for Companion Birds, 2019).
Last reviewed: June 2026
What Crop Candidiasis Is
Candida albicans is a yeast that normally inhabits the avian digestive tract in low numbers. Overgrowth occurs when something tips the balance — antibiotic use that wipes out competing bacteria, hand-feeding formula at the wrong temperature or with poor hygiene, stress, malnutrition, or concurrent illness. The yeast colonizes the crop, proventriculus, and sometimes the mouth, producing fermentation, slowed crop motility, and characteristic white plaques on the mucosa. As described in Carpenter's Exotic Animal Formulary, hand-fed cockatiel chicks are the single highest-risk population.
Clinical Signs
Adult cockatiels present with delayed crop emptying — the crop still contains food hours after a meal — regurgitation of fermented material with a yeasty or sour smell, weight loss, decreased appetite, and white cottage-cheese-like plaques inside the mouth and at the corners of the beak. Chicks show crop stasis, distended fluid-filled crop, regurgitation of partial feeds, and failure to gain weight. Severe cases progress to crop wall ulceration, secondary bacterial infection, and septicemia. A sudden change in vocalizations from a previously talkative cockatiel can be an early sign.
Diagnosis
Diagnosis combines history with crop gram stain or direct cytology. A crop swab transferred to a slide and stained reveals budding yeast in numbers far exceeding the normal one or two per high-power field. Fungal culture identifies the species. Complete blood count and biochemistry assess systemic effects and look for underlying immunosuppression. In chronic or recurrent cases, screening for psittacine beak and feather disease (PBFD), polyomavirus, and hepatic disease is reasonable because Candida is often a sentinel of broader compromise.
Treatment
Nystatin oral suspension is the traditional first-line treatment because it is not absorbed systemically and acts directly on the crop and upper GI surfaces. Standard dosing is 300,000 IU per kg orally twice daily for 7 to 14 days. Fluconazole is preferred when systemic absorption is needed — for severe disease, suspected proventricular involvement, or treatment failures with nystatin — at 5 to 10 mg/kg orally once or twice daily. Itraconazole is reserved for resistant cases because of higher toxicity risk in cockatiels. Avian preventive care including diet conversion and routine wellness exams is outlined in current avian veterinary owner guidance (AAV Basic Care for Companion Birds, 2019). Treatment continues until clinical signs resolve and follow-up cytology is clear.
Hand-Feeding Hygiene For Chicks
In hand-fed chicks, husbandry correction is often more important than antifungals. Use commercial hand-feeding formula prepared fresh for each feed at the correct consistency. Maintain formula temperature at 100 to 104°F at the time of feeding — too cool slows crop emptying and promotes yeast growth, too hot causes crop burns. Clean syringes, feeding tubes, and brooder surfaces between every feed. Never re-warm or save partially fed formula. Quarantine new chicks. Feeding intervals appropriate to age prevent overloading a young crop.
Underlying Cause Workup
Recurrence is the rule when underlying causes are not addressed. Look hard for: long courses of antibiotics in the recent past, low ambient temperature in the brooder or cage, dietary imbalance with seed-heavy feeding and vitamin A deficiency, concurrent viral infection (especially in young birds), hepatic disease in older cockatiels, and chronic stress from overcrowding or insufficient sleep. As described in Carpenter's Exotic Animal Formulary, a converted balanced pelleted diet with dark leafy greens corrects the most common underlying nutritional risk factor.
When to See a Vet
Call your vet today if:
- Crop empties slowly or contents visible hours after the last meal
- Regurgitation with a sour or yeasty smell
- White cottage-cheese-like material inside the mouth or at beak corners
- Hand-fed chick gaining weight slowly or losing weight
- Voice change, reduced talkativeness, or open-mouth breathing
Go to the ER immediately if:
- A hand-fed chick with a distended fluid-filled crop and lethargy
- Crop visibly burned, blackened, or with a hole (crop burn or perforation)
- Sudden severe collapse with bloody or coffee-ground regurgitation
- Active bleeding from the mouth
- Hypothermia (bird cold to the touch) with crop stasis
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Frequently Asked Questions
Why did my cockatiel get yeast after antibiotics?
Broad-spectrum antibiotics suppress the normal bacterial competitors that keep Candida populations low. Within days of antibiotic therapy, yeast can multiply unchecked and produce clinical signs. Prophylactic nystatin during prolonged antibiotic courses in birds is sometimes used to prevent this, particularly in chicks and immunocompromised birds. Discuss with your avian vet if you are starting a long antibiotic course.
How much does crop yeast diagnosis and treatment cost?
Initial avian vet exam typically runs $100 to $300, since avian exams price about 1.5 to 2 times standard. Crop gram stain or cytology adds $40 to $120. Fungal culture is $80 to $200. A 7 to 14 day course of nystatin oral suspension for a cockatiel costs $30 to $80. Fluconazole runs $40 to $120 for a course. CBC and biochemistry add $150 to $400 if underlying disease workup is needed. Hospitalization for severe cases or chicks runs $200 to $500 per day. Catching it early at the first sign of slowed crop emptying is dramatically cheaper than treating septicemia.
Can I clean the mouth plaques off at home?
No. The plaques are firmly adhered and underlying tissue is inflamed; attempts to scrape them risk bleeding, secondary infection, and stress. Antifungal therapy clears plaques over 7 to 14 days as the yeast burden falls. Focus instead on consistent dosing, husbandry, and follow-up cytology.
Is candida contagious to my other birds or to my baby?
Cockatiel-strain Candida albicans is generally not contagious to other healthy birds in well-managed environments, but hand-feeding hygiene matters because shared syringes and brooder contamination can transmit yeast between chicks. Candida in immunocompromised humans is a known risk but transmission directly from pet birds is not commonly documented. Healthy adults are not at meaningful risk from a sick bird.
Will my cockatiel relapse after treatment?
Without addressing the underlying cause, yes. Recurrence rates are high when diet, husbandry, hand-feeding hygiene, or underlying disease is not corrected. A treated bird sent home on the same seed-only diet and the same brooder routine will relapse within weeks. Treatment success depends on long-term husbandry change, not just the antifungal course.
Still Not Sure if Your Bird Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of the inside of the beak, the crop area, and any regurgitated material, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.