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Care library / Health

Health guide, not a diagnosis · Mild

Swim bladder disorder

Also called buoyancy disorder, positive / negative buoyancy disorder, gas bladder disorder

Facts checked against sources on 16 Oct 2026. See sources

Signs

Abnormal buoyancy: floating at the surface (positive buoyancy), lying upside down, or sinking/scooting on the bottom (negative buoyancy)
difficulty staying level

Cause

Usually not a primary swim-bladder disease. Most floating, sinking or lethargic fish have poor water quality or diet problems. Floating after meals is mainly from gulping air while feeding at the surface (goldfish and koi are physostomous: the swim bladder connects to the gut). Body shape of fancy goldfish predisposes them; true swim bladder disease can be bacterial infection (e.g. Aeromonas), and fluid in the bladder or deformities also occur.

What to do

Check water quality first. For floaters, switch from floating to sinking food and reduce feeding competition; peas help mainly because they sink (they are not a complete diet). Fish with buoyancy problems often need MORE food, not less (supplemental feeding with a vet). Persistent cases need a vet (radiographs; possible antibiotics if infection is confirmed, or surgery).

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

Prevention

Feed sinking or pre-soaked food, change diets gradually, avoid crowded surface feeding, keep water clean, and quarantine new fish.

Sources

5 facts checked with sources

CausecorrectedFish Vet (Dr. Jessie Sanders, DVM, DABVP Fish Practice): How to Fix Swim Bladder Disease in Fish · Canadian Veterinary Medical Association: Swim Bladder Problems in Goldfish (2012) · Fish Vet (Dr. Jessie Sanders, DVM, DABVP Fish Practice): Top 5 Most Common Goldfish Diseases · Sirri et al. 2020, Swim Bladder Disorders in Koi Carp (Cyprinus carpio), Animals 10(11):1974 (doi:10.3390/ani10111974), PubMed abstract
SignsCanadian Veterinary Medical Association: Swim Bladder Problems in Goldfish (2012) · Merck Veterinary Manual (pet owner): Routine Health Care of Fish
What to docorrectedFish Vet (Dr. Jessie Sanders, DVM, DABVP Fish Practice): How to Fix Swim Bladder Disease in Fish · Fish Vet (Dr. Jessie Sanders, DVM, DABVP Fish Practice): How to Fix a Floating Goldfish · Canadian Veterinary Medical Association: Swim Bladder Problems in Goldfish (2012) · Merck Veterinary Manual (professional): Management of Aquarium Fish
PreventionCanadian Veterinary Medical Association: Swim Bladder Problems in Goldfish (2012) · Fish Vet (Dr. Jessie Sanders, DVM, DABVP Fish Practice): How to Fix Swim Bladder Disease in Fish
Other namescorrectedFish Vet (Dr. Jessie Sanders, DVM, DABVP Fish Practice): How to Fix Swim Bladder Disease in Fish · Merck Veterinary Manual (professional): Management of Aquarium Fish

Species often affected

60 species

White cloud mountain minnowTanichthys albonubes

Easy4 cm14–22 °C

BettaBetta splendens

Easy6.5 cm24–28 °C

Honey gouramiTrichogaster chuna

Easy5.5 cm22–27 °C

Pearl gouramiTrichopodus leerii

Easy12 cm24–28 °C

Three-spot gouramiTrichopodus trichopterus

Easy15 cm24–30 °C

Kissing gouramiHelostoma temminckii

Moderate30 cm22–30 °C

Sparkling gouramiTrichopsis pumila

Easy4 cm24–28 °C

Giant gouramiOsphronemus goramy

Moderate70 cm22–28 °C

Paradise fishMacropodus opercularis

Moderate6.7 cm10–22 °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

Moonlight gouramiTrichopodus microlepis

Easy15 cm25–30 °C

Snakeskin gouramiTrichopodus pectoralis

Easy30 cm22–30 °C

Thick-lipped gouramiTrichogaster labiosa

Easy10 cm22–27 °C

Banded gouramiTrichogaster fasciata

Easy10 cm21–28 °C

Croaking gouramiTrichopsis vittata

Easy7 cm22–28 °C

Three-striped croaking gouramiTrichopsis schalleri

Easy5 cm22–28 °C

Chocolate gouramiSphaerichthys osphromenoides

Moderate6 cm26–31 °C

Vaillant's chocolate gouramiSphaerichthys vaillanti

Moderate5.5 cm21–25 °C

Licorice gouramiParosphromenus deissneri

Moderate4 cm22–27 °C

Nagy's licorice gouramiParosphromenus nagyi

Moderate4 cm22–27 °C

Frail gouramiCtenops nobilis

Moderate10 cm15–25 °C

Round-tailed paradise fishMacropodus ocellatus

Moderate8 cm10–22 °C

Black paradise fishMacropodus spechti

Easy8 cm20–30 °C

Red-finned paradise fishMacropodus erythropterus

Easy8 cm20–30 °C

Spotted gouramiMalpulutta kretseri

Easy5 cm23–26 °C

Java combtailBelontia hasselti

Moderate20 cm21–26 °C

Ceylonese combtailBelontia signata

Moderate18 cm22–27 °C

Red-tail giant gouramiOsphronemus laticlavius

Moderate50 cm22–30 °C

Peaceful bettaBetta imbellis

Moderate6 cm24–28 °C

Emerald bettaBetta smaragdina

Moderate7 cm24–28 °C

Mahachai bettaBetta mahachaiensis

Moderate6 cm22–28 °C

White-margined bettaBetta albimarginata

Moderate3 cm24–28 °C

Channoides bettaBetta channoides

Moderate4 cm24–28 °C

Brunei beautyBetta macrostoma

Moderate10 cm20–25 °C

Javan mouthbrooding bettaBetta picta

Moderate5 cm22–27 °C

Wine-red bettaBetta coccina

Moderate5.6 cm22–27 °C

Brownorum bettaBetta brownorum

Moderate3 cm24–30 °C

Persephone bettaBetta persephone

Moderate3.5 cm22–27 °C

Foerschi bettaBetta foerschi

Moderate7 cm24–28 °C

Akar bettaBetta akarensis

Easy8 cm22–27 °C

Spotted bettaBetta unimaculata

Moderate11.5 cm21–26 °C

ShubunkinCarassius auratus

Easy30 cm4–26 °C

Golden orfeLeuciscus idus

Moderate50 cm4–20 °C

Rosy red minnowPimephales promelas

Easy10 cm4–26 °C

European bitterlingRhodeus amarus

Pumpkinseed sunfishLepomis gibbosus

Moderate20 cm4–25 °C

Bluegill sunfishLepomis macrochirus

Moderate19 cm4–26 °C

Blue-spotted sunfishEnneacanthus gloriosus

Moderate7.5 cm10–22 °C

Banded sunfishEnneacanthus obesus

Moderate9 cm10–22 °C

Everglades pygmy sunfishElassoma evergladei

Moderate3 cm10–26 °C

Three-spined sticklebackGasterosteus aculeatus

Moderate8 cm4–20 °C

Nine-spined sticklebackPungitius pungitius

Moderate6.5 cm10–20 °C

Sterlet sturgeonAcipenser ruthenus

Hard100 cm4–18 °C

TenchTinca tinca

Easy60 cm4–25 °C

Golden ruddScardinius erythrophthalmus

Easy50 cm4–22 °C

SunbleakLeucaspius delineatus

Easy9 cm4–22 °C

Vietnamese white cloudTanichthys micagemmae

Easy3 cm18–23 °C