Care library / Health

Health guide, not a diagnosis · Serious if left

Popeye

Also called exophthalmia, exophthalmos

Facts checked against sources on 16 Oct 2026. See sources

Signs

One or both eyes bulge outward
the eye surface may be white or cloudy

Cause

Fluid building up behind the eye. One eye: often injury. Both eyes: often chronically poor water or a systemic disease, e.g. bacterial infection (Aeromonas, mycobacteriosis), intraocular parasites (Tetrahymena), or viral disease.

What to do

Fix water quality and diet; swelling goes down slowly (weeks to months). Hobby source: Epsom salt 1-3 teaspoons per 5 US gallons (about 19 L) in a quarantine tank to reduce swelling; antibiotics for internal infection preferably in food. Vet sources: antibiotics should be chosen by lab testing; internal Tetrahymena is untreatable.

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

Prevention

Good water quality (avoid overstocking, overfeeding and infrequent water changes) and avoiding physical injury (gentle handling, no abrasive rocks or nets, no jumpy fish with boisterous tankmates).

Medicines used for it

Always read the label first

Antibacterial treatmentsAntibacterial

Seachem FocusAntibacterial

Seachem KanaPlexAntibacterial

API MelafixAntibacterial

Fritz MaracynAntibacterial

Fritz Maracyn 2Antibacterial

Sources

5 facts checked with sources

Species often affected

101 species

OscarAstronotus ocellatus

Moderate45.7 cm22–27 °C

Silver arowanaOsteoglossum bicirrhosum

Hard90 cm24–30 °C

Alligator garAtractosteus spatula

Spotted garLepisosteus oculatus

Rainbow snakeheadChanna bleheri

Easy17 cm14–28 °C

Red-bellied pacuPiaractus brachypomus

Hard88 cm23–28 °C

Senegal bichirPolypterus senegalus

Moderate50 cm24–28 °C

RopefishErpetoichthys calabaricus

Moderate40 cm24–28 °C

Elephantnose fishGnathonemus petersii

Hard23 cm24–28 °C

African butterflyfishPantodon buchholzi

Moderate12 cm24–30 °C

Marbled hatchetfishCarnegiella strigata

Easy3.5 cm24–28 °C

PencilfishNannostomus beckfordi

Moderate6.5 cm21–27 °C

Pea pufferCarinotetraodon travancoricus

Moderate3 cm24–28 °C

Bumblebee gobyBrachygobius doriae

Moderate3.5 cm24–28 °C

Indian glassfishChanda ranga

Easy8 cm22–28 °C

Lyretail killifishAphyosemion australe

Easy6 cm21–24 °C

Clown knifefishChitala ornata

Hard100 cm24–28 °C

Black ghost knifefishApteronotus albifrons

Moderate50 cm24–28 °C

Peacock eelMacrognathus siamensis

Moderate30 cm24–28 °C

Six-barred distichodusDistichodus sexfasciatus

Hard75 cm22–26 °C

Longnose distichodusDistichodus lusosso

Moderate38 cm22–26 °C

Banded leporinusLeporinus fasciatus

Moderate27 cm22–28 °C

Red-bellied piranhaPygocentrus nattereri

Hard35 cm24–28 °C

Black piranhaSerrasalmus rhombeus

Hard45 cm24–28 °C

Wimple piranhaCatoprion mento

Hard15 cm23–26 °C

Black pacuColossoma macropomum

Hard60 cm22–28 °C

Tiger trahiraHoplias malabaricus

Moderate65 cm20–26 °C

Pink-tailed chalceusChalceus macrolepidotus

Easy25 cm23–28 °C

Northern snakeheadChanna argus

Hard100 cm4–26 °C

Giant snakeheadChanna marulius

Moderate60 cm22–28 °C

Giant snakeheadChanna micropeltes

Moderate130 cm22–28 °C

Chevron snakeheadChanna striata

Moderate100 cm23–27 °C

Dwarf snakeheadChanna gachua

Easy20 cm18–28 °C

Ceylon snakeheadChanna orientalis

Moderate10 cm16–24 °C

Northern dwarf snakeheadChanna asiatica

Moderate35 cm15–25 °C

Barca snakeheadChanna barca

Moderate100 cm10–28 °C

Golden snakeheadChanna stewartii

Moderate30 cm16–25 °C

Orange-spotted snakeheadChanna aurantimaculata

Moderate40 cm18–26 °C

Ornate snakeheadChanna ornatipinnis

Ocellated snakeheadChanna pleurophthalma

Moderate40 cm22–28 °C

Black snakeheadChanna melasoma

Moderate30 cm22–28 °C

Burmese jewel snakeheadChanna harcourtbutleri

Forest snakeheadChanna lucius

Moderate53 cm22–28 °C

African snakeheadParachanna obscura

Moderate50 cm26–30 °C

Amazon leaffishMonocirrhus polyacanthus

Hard10 cm24–28 °C

Guyana leaffishPolycentrus schomburgkii

Hard5.5 cm22–26 °C

African leaffishPolycentropsis abbreviata

Hard8 cm26–31 °C

Gangetic leaffishNandus nandus

Moderate20 cm22–26 °C

Pike livebearerBelonesox belizanus

Moderate15 cm24–30 °C

Four-eyed fishAnableps anableps

Moderate30 cm25–31 °C

Elongate glassfishChanda nama

Wolf's glassfishParambassis wolffii

Moderate20 cm18–25 °C

Asian arowanaScleropages formosus

Moderate90 cm22–28 °C

Black arowanaOsteoglossum ferreirai

Hard90 cm24–30 °C

Jardini arowanaScleropages jardinii

Moderate100 cm24–29 °C

Spotted saratogaScleropages leichardti

Moderate100 cm24–30 °C

African arowanaHeterotis niloticus

Moderate100 cm24–30 °C

ArapaimaArapaima gigas

Hard250 cm24–30 °C

Ornate bichirPolypterus ornatipinnis

Moderate60 cm25–28 °C

Delhezi bichirPolypterus delhezi

Easy44 cm24–30 °C