Care library / Health

Health guide, not a diagnosis · Serious

Ulcers & red sores

Also called ulcer disease, aeromonas, red sores

Signs

Open red sores on the body
Red streaks in fins
Scale loss

Cause

Bacteria such as Aeromonas, often after poor water or injury. Common in goldfish and koi.

What to do

Improve water at once and use an antibacterial treatment; isolate badly affected fish.

If a fish is badly ill, talk to an aquatic vet.

Prevention

Clean water and quarantine.

Medicines used for it

Always read the label first

Antibacterial treatmentsAntibacterial

Aquarium saltSalt & water care

Species often affected

21 species

White cloud mountain minnowTanichthys albonubes

Easy4 cm14–22 °C

Fancy goldfishCarassius auratus

Easy20 cm10–24 °C

Comet goldfishCarassius auratus

Easy30 cm10–24 °C

KoiCyprinus rubrofuscus

Moderate70 cm4–25 °C

MedakaOryzias latipes

Easy4 cm16–22 °C

ShubunkinCarassius auratus

Easy30 cm4–26 °C

Golden orfeLeuciscus idus

Moderate50 cm4–22 °C

Rosy red minnowPimephales promelas

Easy10 cm4–26 °C

European bitterlingRhodeus amarus

Moderate8 cm5–22 °C

Pumpkinseed sunfishLepomis gibbosus

Moderate20 cm4–25 °C

Bluegill sunfishLepomis macrochirus

Moderate25 cm4–26 °C

Blue-spotted sunfishEnneacanthus gloriosus

Moderate9 cm8–24 °C

Banded sunfishEnneacanthus obesus

Moderate9 cm8–24 °C

Everglades pygmy sunfishElassoma evergladei

Moderate3 cm10–26 °C

Three-spined sticklebackGasterosteus aculeatus

Moderate8 cm4–22 °C

Nine-spined sticklebackPungitius pungitius

Moderate6 cm4–20 °C

Sterlet sturgeonAcipenser ruthenus

Hard100 cm4–20 °C

TenchTinca tinca

Easy50 cm4–25 °C

Golden ruddScardinius erythrophthalmus

Easy40 cm4–25 °C

SunbleakLeucaspius delineatus

Easy9 cm4–22 °C

Vietnamese white cloudTanichthys micagemmae

Easy4 cm16–24 °C