Betta Fish Diseases and Symptoms: Complete Identification Guide

Recognising disease early is the difference between a quick recovery and a lost fish. This betta fish diseases symptoms identification guide from Gensou Aquascaping at 5 Everton Park, Singapore, walks through the most common illnesses affecting Betta splendens, their visual signs, and first-response treatments. With over 20 years of hands-on experience, we have treated hundreds of sick bettas — and the single most consistent lesson is that early detection saves lives.

Ich (White Spot Disease)

Ich is caused by the protozoan parasite Ichthyophthirius multifiliis and presents as tiny white granules scattered across fins and body — like grains of salt. Affected fish often flash (rub against surfaces) and clamp their fins. Ich thrives when temperature fluctuates or drops below 25 °C, making it a particular risk in air-conditioned rooms in Singapore.

Treatment: raise temperature gradually to 30 °C over 24 hours and add aquarium salt at 1–2 grams per litre. The heat accelerates the parasite’s lifecycle, pushing it into the free-swimming stage where salt and medication can kill it. Maintain elevated temperature for 10–14 days, then gradually return to 26–28 °C.

Fin Rot

Fin rot is a bacterial infection that erodes fin edges progressively. Early signs include ragged, uneven fin margins with white, brown, or reddish tips. Advanced cases show significant tissue loss, sometimes reaching the body. Fin rot almost always traces back to poor water quality — elevated ammonia or nitrite, infrequent water changes, or overcrowded conditions.

Mild cases respond to improved water quality alone. Perform 25–30 % daily water changes for a week, ensuring water is dechloraminated and temperature-matched. If deterioration continues, treat with an antibacterial medication containing methylene blue or erythromycin, available at local aquarium shops for $5–$10.

Velvet (Gold Dust Disease)

Piscinoodinium pillulare causes velvet — a parasitic infection that coats the fish in a fine gold or rust-coloured dust, visible under angled light. Bettas with velvet clamp fins, lose appetite, and become lethargic. The dust-like appearance is subtler than ich spots and often missed until the disease has advanced.

Darken the tank (the parasite photosynthesises) and treat with copper-based medication following the product’s dosage instructions precisely. Copper is effective but toxic at high concentrations, especially to snails and shrimp — remove invertebrates before treatment. Raise temperature to 28–30 °C concurrently.

Dropsy

Dropsy is not a disease but a symptom — fluid accumulation in the body cavity causing the abdomen to swell and scales to protrude outward in a pinecone-like pattern. By the time pineconing is visible, internal organ damage (typically kidney failure) is severe. Causes include chronic poor water quality, bacterial infection, and internal parasites.

Honest assessment: dropsy at the pinecone stage carries a very poor prognosis. Epsom salt baths (1 tablespoon per 20 litres) may reduce swelling temporarily. Antibacterial food containing kanamycin offers the best chance if the fish is still eating. Prevention through proper tank cycling and consistent maintenance is far more effective than any cure.

Swim Bladder Disorder

A betta floating at odd angles, struggling to dive, or sinking to the bottom likely has swim bladder problems. Causes range from constipation (the most common) to bacterial infection or physical injury. Overfeeding and low-quality dried foods that expand in the stomach are frequent triggers.

Fast the fish for 48 hours, then offer a small piece of blanched, de-shelled pea. If the issue is constipation, this usually resolves symptoms within a day. Persistent swim bladder dysfunction after fasting suggests a deeper cause — bacterial infection or organ damage — requiring medication or veterinary assessment.

Columnaris (Cotton Wool Disease)

Columnaris is a bacterial infection (genus Flavobacterium) that produces white or greyish cotton-like growths on the mouth, body, or fins. It progresses rapidly — a fish can go from initial spots to severe tissue damage within 48 hours. Columnaris thrives in warm, hard water, though Singapore’s soft tap water reduces but does not eliminate risk.

Treat aggressively with antibacterial medication. Lower temperature slightly to 24–25 °C, as columnaris bacteria multiply faster in warmer water — opposite to the ich treatment protocol. Do not add salt, which can worsen columnaris in some strains.

Prevention: The Best Medicine

Nearly every betta disease links back to stress and poor water conditions. A cycled tank, stable temperature, appropriate feeding, and weekly water changes prevent the vast majority of illness. Quarantine all new fish and plants for two weeks before adding them to an established tank. Keep a basic medication kit — methylene blue, aquarium salt, and an antibacterial — on hand for emergencies.

This betta fish diseases symptoms guide covers the most frequent conditions, but observation remains your most powerful tool. Know what your betta looks like when healthy, and you will spot problems the moment they begin.

Related Reading

• Why Is My Betta Fish Turning White? Causes and Treatment
• Why Is My Betta Fish Bloated? Dropsy, Constipation and Swim Bladder
• Betta Fish Water Temperature Guide: Ideal Range and Heater Tips
• Betta Fish Feeding Guide: How Much, How Often and Best Food
• How to Cycle a Betta Tank: Fishless and Fish-In Methods