why is my fish not eating

Why is my fish not eating!?

'Why is my fish not eating!?' - This is a very common question I get and one that has many answers. Loss of appetite is one of the first signs many people notice when things aren’t quite right with their fish. Appetite loss are commonly due to diseases that are related to water conditions, infectious diseases, non-infectious diseases, bad food and more. In most cases, when one fish is sick, there is the potential that the entire fish population is at risk of getting sick. Note that the use of non-targeted medicines for fish diseases without a proper diagnosis could cause more harm and complicate the matter. This could lead to more pain and suffering. In this post, we will cover the most common reasons for lack of appetite in the fish.


Water quality is the single most important factor for good fish health. They live in it, swim in it, breathe in it and excrete into it. Many biological processes depend on the water conditions to be just right for the type of fish. As such, fish can lose their appetite if there is a build up of fish wastes (e.g. ammonia, nitrite or nitrate), if the water temperature is too low or too high, if the dissolved oxygen is low, if the dissolved carbon dioxide is high, if the pH is wrong and if there are toxins in the water. It is thus important to check these parameters when investigating the reason for loss of appetite. There are many different aquarium water test kits available at your local fish shop.


Infectious causes are many and they will affect your fish’s health and appetite. There are broad categories of disease-causing agents just like in any other animal. These include viruses, bacteria, protozoa, worms, crustacea, fungi and more. Infectious diseases are most commonly spread by the introduction of new fish and plants into your tank or pond. Any sort of stressors can exacerbate the conditions. With the exception of a few diseases (e.g. white spot disease, fish lice), many require microscopic examination to arrive at a diagnosis. It is highly advisable that you get an experienced aquatic veterinarian to investigate your fish problems because many diseases produce non-specific clinical signs. With the correct diagnosis, you can use the correct treatments.

Goldfish eating food on the surface


In terms of non-infectious diseases, the list is just as long. Your fish may have an internal disease, like a tumour or a gut blockage. Perhaps your food has gone off (check the use-by date, smell and check that it has been stored correctly). Perhaps your fish has just become picky and is bored of eating the same food every day. Along with the branded food you feed your fish try feeding them a variety of live foods. If they are still not eating, don’t leave it too long. Call the fish vet.

Author Bio

Dr Richmond Loh is a trusted vet and the Founder of thefishvet.com.au, an online blog that offers valuable information on people wanting to better care for their pet fish.

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Posted by Dr Richmond Loh