Bloating

Swollen abdomen or scales standing out (pinecone appearance) — may indicate dropsy or organ failure; act quickly. Compare your fish with the reference photo above and cross-check your logged parameters in Aquarium Tracker before medicating.

SymptomBloating

CausesInternal bacterial infection (dropsy) — scales pineconing is a late sign / Constipation from dry foods or overfeeding

TreatmentTest water quality and perform an immediate partial water change / Isolate the fish in a hospital tank if possible

PreventionQuarantine new fish; zero ammonia & nitrite

What causes bloating?

Internal bacterial infection (dropsy) — scales pineconing is a late sign
Constipation from dry foods or overfeeding
Kidney or swim-bladder issues from long-term poor water quality
Fluid retention following organ damage

What to check before medicating

What to measure	Typical target	What an off reading points to
Ammonia (NH₃/NH₄⁺)	0 ppm	Anything above zero means the biological filter cannot keep up. Toxic to fish long before it is high enough to feed algae.
Nitrite (NO₂⁻)	0 ppm	A reading above zero points to an immature or disrupted filter — common after a media change, medication, or a large clean.
Nitrate (NO₃⁻)	5–20 ppm planted · under 10 ppm reef	Climbing nitrate signals more waste going in than water changes and plants export. Near zero in a planted tank starves plants and favours algae.
Temperature	within your species range, steady	Warmer water holds less oxygen and speeds both metabolism and pathogen growth. Sudden swings stress fish more than a steady figure at either end.
Feeding amount and frequency	eaten within 2–3 minutes, no residue	Uneaten food is the most common hidden nutrient source. It breaks down out of sight in substrate and filter media.
Recent changes	note anything from the last 2–3 weeks	New livestock, plants, media, lighting or dosing are the usual trigger. The cause often precedes the symptom by a fortnight.

Take these readings first. A large share of what looks like disease is a water quality problem, and medicating a tank whose ammonia is climbing treats the symptom while the cause keeps working.

Treatment steps

Test water quality and perform an immediate partial water change
Isolate the fish in a hospital tank if possible
Withhold food for 24–48 hours if constipation is suspected; offer deshelled pea for herbivores/omnivores only if appropriate
Pineconing often indicates advanced internal infection — prognosis is guarded
Consult a vet or experienced specialist before antibiotics

Prevention

Test ammonia, nitrite and nitrate on a schedule rather than only when something looks wrong
Keep parameters stable — sudden swings after a large water change cause more problems than the readings they correct
Avoid overstocking; crowding raises waste and stress at the same time
Feed only what is eaten in a few minutes, and remove the rest

Frequently asked questions

Is bloating contagious to my other fish?

Generally not. Dropsy is a symptom of organ failure rather than a disease in itself, though the underlying infection can occasionally spread.

How quickly do I need to act?

Quickly, though be realistic: by the time scales are pineconing, prognosis is poor. Focus on the tank conditions and the comfort of the affected fish.

Should I treat in the display tank or a hospital tank?

A separate hospital tank is preferable where the fish is well enough to move: doses are easier to control, and many medications harm invertebrates, plants or the biological filter. Treat in the display only when the whole tank is affected or moving the fish would add more stress than the treatment removes.