Constipation and overfeeding

WatchSign

Also called: Bloated belly, Overfed fish

What you see

A swollen belly, but the scales lie FLAT and the fish stays active and keeps begging for food. Most often after generous feeding with dry food. Females in breeding season fill out naturally — symmetrically, with no other signs.

How to tell it from its look-alikes

First, the pinecone test from above: if the scales stand out, this is not constipation but dropsy. A symmetrically rounded female behaving normally is most likely just carrying eggs — if she does not spawn, she resorbs them naturally, and that is normal. The “egg-bound fish” that forums worry about so much is, per a board-certified fish veterinarian, a rarity — mostly a fake diagnosis. A one-sided lump growing over weeks is a different story — see the dropsy separators.

Dropsy

The pinecone test from above is the main separator: a swollen belly with FLAT scales is usually overfeeding or a female's eggs, while raised scales mean fluid building up inside — organ failure. If the fish swelled slowly, over weeks, while wasting away — look at mycobacteriosis. A one-sided, slowly growing bulge suggests a tumour instead. Worth knowing: dropsy is a sign, not a disease — many causes produce it, most often a bacterial infection in failing kidneys.

The dangerous mistake

Squeezing a fish to “help” release the eggs — never: that ruptures internal organs. The second mistake is a week of “fasting and peas” for a fish that is genuinely ill: if it does not improve within days, or scales begin to lift, it was not constipation.

Water first

In a young tank, most “disease” is not disease — it is ammonia or nitrite poisoning, and no medicine treats that. Before buying anything, test ammonia, nitrite and nitrate. If you keep the cycle log, the answer is already there.

New tank syndrome

What to do

For goldfish and koi the vet-endorsed route: one to three days without food, then a frozen, shelled green pea — never a dried one. For other species simply feed less and more varied — the pea advice has veterinary backing only for goldfish and koi. A gravid female needs nothing done: give spawning conditions or simply wait, and she will resorb the eggs.

What to expect

Usually resolves on its own within days. Bloating that persists or grows is the signal to go back to the dropsy and mycobacteriosis separators.

This reference helps you recognise and tell conditions apart — it does not make the diagnosis. Only a microscope or a veterinarian confirms one. Use medicines exactly per the label, ideally in a quarantine tank, because several of them kill filter bacteria.