A puffer that stops eating is a genuine warning sign, because a healthy puffer begs constantly. The good news is that the causes fall into a short, checkable list. Work through it in order — the first three explain the large majority of cases.
The Five-Minute Checklist
- Test the water. Ammonia, nitrite, nitrate, temperature, and specific gravity for brackish species. Ammonia above zero stops a puffer eating within a day.
- Look at the mouth. If the beak protrudes past the lips, the fish physically cannot feed — see the teeth page.
- Count the days since it arrived. New puffers commonly refuse food for three to seven days.
- Check the faeces. White and stringy means internal parasites.
- Check for a bully. A puffer being chased off food hides and thins out.
Why a Puffer Fish Stops Eating
| Cause | Other signs | Fix |
|---|---|---|
| New arrival stress | Hiding, pale, otherwise healthy | Dim lights, offer live blackworms, wait 3–7 days |
| Ammonia or nitrite | Gasping, red gills, clamped fins | 50% water change now, then daily until zero |
| Overgrown teeth | Chases food, cannot take or crush it | Soft food short term; trimming if advanced |
| Internal parasites | Thin body, white stringy faeces | Praziquantel then levamisole in quarantine |
| Wrong salinity | Brackish species, dull colour, lethargy | Correct SG gradually — see salinity guide |
| Wrong food | Interested but will not take pellets or flake | Offer live or frozen; puffers rarely take dry food |
| Bullying | Hiding, clamped fins, nipped edges | Separate; see aggression |
| Temperature too low | Sluggish, slow to respond | Bring to 77–80°F gradually |
| Constipation | Swollen belly, no faeces | Fast 2–3 days, then shelled prey |
Getting a New Puffer to Eat
- Dim the tank and the room for the first few days and keep traffic past the glass low.
- Offer live food. Live blackworms break more hunger strikes than anything else; live pest snails work well for pea and figure 8 puffers.
- Feed at the same time each day and leave the room. Many new puffers will not eat while watched.
- Target-feed with tweezers or a pipette so food reaches the fish rather than the substrate.
- Remove uneaten food after an hour so it does not foul the water and make the problem worse.
- Give it a week before escalating to medication. Most healthy new puffers start eating within seven days.
Puffer Fish Hiding
Some hiding is normal. Congo and hairy puffers spend most of the day buried or wedged, and every puffer has a favourite corner. It becomes a symptom when it is new behaviour, or when it comes with clamped fins, pale colour, refusing food or rapid gilling.
- New tank: normal for the first week. Add more cover rather than less — a fish with hiding places explores sooner than one with none.
- Sudden hiding in an established tank: test water first, then look for a tank mate that has started chasing.
- Hiding plus pale colour: treat as illness — see the diseases page.
Puffer Lying on the Bottom
Resting on the substrate is normal puffer behaviour — they have no swim-bladder-driven need to hover and they park regularly. Distinguish normal resting from a problem:
| Normal | Concerning |
|---|---|
| Upright, fins relaxed, alert eyes | Leaning, rolling or on its side |
| Moves off readily when you approach | Unresponsive or struggling to lift off |
| Still eating normally | Refusing food alongside it |
| Normal colour | Pale, blotchy or very dark |
| Steady gill movement | Rapid gilling or gasping |
If the fish is on its side or struggling to stay off the bottom, go to the swimming and breathing page.
Frequently Asked Questions
Why is my puffer fish not eating?
Check water quality first, then the beak. Ammonia or nitrite above zero, overgrown teeth that stop the fish taking food, internal parasites, new-arrival stress, wrong salinity for a brackish species and bullying account for almost every case.
How long can a puffer fish go without eating?
A healthy adult puffer can go one to two weeks without lasting harm, and new arrivals commonly refuse food for three to seven days. Small species such as pea puffers have less reserve and should be eating within a week.
How do I get my new puffer fish to eat?
Dim the lights, keep traffic past the tank low, and offer live blackworms or live pest snails. Feed at the same time daily and leave the room, target-feed with tweezers, and remove uneaten food after an hour.
Why is my puffer fish hiding all the time?
Some hiding is normal, especially in a new tank or for burrowing species. Sudden hiding in an established tank usually means a water quality problem or a tank mate that has started chasing. Pale colour or clamped fins alongside it points to illness.
Is it normal for a puffer fish to lie on the bottom?
Yes. Puffers rest on the substrate regularly and burrowing species stay there most of the day. It is only a problem if the fish leans or rolls onto its side, cannot lift off, is refusing food, looks pale, or is gilling rapidly.
My puffer eats but stays thin, what is wrong?
That pattern is the classic sign of internal parasites, particularly in wild-caught fish. Look for white stringy faeces and treat with praziquantel followed by levamisole in a quarantine tank, feeding well throughout.