Troubleshooting: Fish
Why is my new marine fish not eating?
A fish ignores food, spits it out or hides at feeding time. New fish often skip a day or two; a settled fish that stops eating is more worrying.
Last checked . How we check
What should I check first?
- How long since it last ate, and how long since it was added?
- Is another fish chasing it away from food?
- Look at breathing, spots, fins and belly shape.
- Test ammonia, nitrite, salinity and temperature.
- What does this species eat in the wild? Check its profile on Seafan.
What is most likely causing it?
Most likely first. The order is our reading of how often the sources link each cause to this symptom.
- Stress after moving. A fish added in the last few days that hides. BRS suggests an acclimation box in established tanks so newcomers are not bullied.
- Bullying. A tankmate chases it at feeding time; torn fins.
- The wrong food. A specialist feeder, such as a mandarin that hunts copepods, or a fish bought to do a job. The cleaner wrasse usually starves in home tanks (LiveAquaria rates it difficult).
- Disease. Fast breathing, spots, a sunken belly, or white stringy faeces (our reading). See white spots.
- Water quality. Several fish off their food at once.
What should I do?
- Offer small amounts of a varied, high-quality frozen food, rinsed, two or three times a day.
- Soak food in garlic or a vitamin supplement if you use one; many keepers find it tempts fish (typical, check).
- Use an acclimation box or move rock to break up territories if a tankmate is bullying.
- For specialist feeders, see the species page before buying again.
- Next time, ask the shop to show you the fish eating before you buy (our reading).
What not to do
- Overfeeding the tank to tempt one fish: the extra food fouls the water.
When should I get help?
Something dying right now? Go to the emergency playbooks.