Why Has My Goldfish Lost Its Appetite?

Every now and again goldfish will go off their food. To get them eating again, it’s important to know the reasons goldfish lose their appetite in the first place. If the correct cause of the loss of appetite is known, the necessary adjustments or treatments can be applied.

The reasons for goldfish losing their appetite fall into two main categories: goldfish diseases and environmental stress.

Goldfish Diseases

Constipation causes loss of appetite in goldfish. As regular readers of this blog will know from Goldfish Diet and Nutrition, goldfish do not have a stomach for holding and digesting food. Instead food passes through a goldfish’s digestive tract without stopping. If there is a blockage at one end there is no buffer zone to absorb the impact of food coming in at the other end, so feeding will stop.

A goldfish suffering from goldfish ick can also lose its appetite. Although not a guaranteed symptom of goldfish ick, it can occur in more advance cases of the illness and is due to a general and deeply unwell feeling caused by a goldfish disease that can eventually be fatal.

There is one more disease that can cause a loss of appetite in goldfish, but it is very rare among them. It is known as Hole in the Head Disease, or Freshwater Head and Lateral Line Erosion. More common among other types of freshwater fish it is a dangerous, but treatable condition that can be a cause of loss of appetite.

Environmental Stress

A change in diet can cause goldfish to go off their food. Obviously this is one of the easiest causes of appetite loss among goldfish to identify. If goldfish are changed onto a healthy diet from a poor one, they may well not eat for a few days. Their reticence to eat is due to being used to the old diet, and the slight stress of the change that may worry them until they get used to the new food.

Another environmental factor that may cause goldfish to lose their appetite is temperature variations. Again, regular readers of this blog will know from Preparing a Goldfish Pond for Winter that the natural seasonal drop in temperature can result in goldfish going the whole Winter without food. In parts of the world where Summer temperatures can fall sharply, pond goldfish can lose their appetite as a result.

Changes in water quality can also cause goldfish to stop eating, especially pH levels outside the optimum range. Goldfish that are put into new tanks that have abnormally high levels of ammonia and nitrite will also be susceptible to appetite loss.

Introducing goldfish into a new environment e.g. a new aquarium or pond, or bringing them back from the pet shop may well lose their appetite simply because of the stress of the move.

Finally, goldfish that see a new face pressed against the aquarium glass at feeding time, or goldfish that have to suffer a child splashing the surface of the water or tapping the aquarium glass will be frightened out of feeding. The same goes for pond goldfish that fear predation by a cat or heron. They simply will not surface for food, and will not emerge from hiding.

6 Responses to “Why Has My Goldfish Lost Its Appetite?”

  1. The Goldfish Guy Says:

    Great information!

    You hit everything right on the money. There are so many reasons why goldfish can lose their appetite and you covered them all.

    You have an excellent goldfish blog. You will help many people with their goldfish questions.

    Keep up the great work!


    Jamie Boyle
    The Goldfish Guy

  2. claudia boyd Says:

    We have had these ponds now for 20 years – the deeper pond for koi and the more shallow pond for goldfish of which some of them are many years old.
    Their predators are raccoons as well as herons. The latter have been hunting in our pond quite successfully the last few weeks. After trying everything from nets to providing cover for the goldfish we finally have hit on something quite successful – a very large mirror which seems to have startled them back into flight. Our problem: the fish do not want to come out from hiding and refuse to eat. We have removed the cover (they still have lilies) but are huddling underneath the waterfall.
    Do you have any suggestions?
    We are grateful for any help.
    Claudia Boyd

  3. Amanda Says:

    I had two goldfish, Minnie and Edward. Minnie unfortunately passed away yesterday… and petsmart believes that it was stress related. Minnie and Edward have been together for about a year and 3 months, and they always got along… three days ago, Edward starting beating up on Minnie, shoving her behind the filter, pushing her into the decorations in their tank, whacking her with his body… etc.
    Now that Minnie is gone… Edward has not been acting the same… he has lost his appetite and doesnt seem to be as rambunctious as he normally is. He was always the first one to the top of the tank for food and ate like he was never fed before. Now, he seems disinterested.
    What could this be? Is it him missing her? He has no sores, no bulging eyes, no rips on fins.

  4. hi Says:

    my goldfish died today i saw him laying on the bottom of the bowl it was sad i only have him four days. and his name is swimmie or swimy and i have one more fish that is not died his name is brok he is four days old and what do you think killed swimmie

  5. Ruby Cookie Blue Says:

    To “hi”
    If your goldfish was in a bowl, thats what killed Swimmy, lack of oxygen and probs no filter to keep the water moving.
    If not, probs where he came from… Usually if fish are from pet shops they never make a month :/

  6. paris Says:

    hi thank you you helped me a lot

Leave a Reply