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Why is my goldfish lethargic, lying on bottom, but still eating?

Updated On September 23rd, 2025

Pet's info: Fish | Gold Fish

My fish fantail goldfish Mort has become very lethargic. He usually comes up to the top for his food but recently he has just been lying on the bottom of the tank. He still eats but seems tired. I've had him about 8 years now.

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2 Answers

Most Helpful Answer

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on January 3rd, 2020

Check the water chemistry first. You can use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Perform a partial water change, if indicated, to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. Goldfish are cold water fish and do best between 68 F and 72 F. You can use plain aquarium salt (NOT table or Epsom salt) as a general tonic to reduce stress, improve gill function, treat minor infection and aid in recovery. Dissolve up to 1 teaspoon of salt per gallon of water in a cup or two of tank water and gently pour it into the tank. In the absence of other symptoms, medication would not be recommended at this time.

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Other Answers

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    Answered By Angel Alvarado, LVT

    Licensed Veterinary Technician

    Published on June 1st, 2018

    Check the water quality and water chemistry. You can use a home test kit or submit a sample for testing. Most pet stores will do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with a nitrate level of 20 ppm or less. Partial water changes can be done to stabilize chemistry or improve water quality. Use only conditioned water that is temperature matched to prevent further stress or shock. Goldfish are cold water fish and do best between 65 F and 72 F. Consider a much larger tank since goldfish produce a larger than average bio load (wastes). This can lead to poor water quality very quickly. Ideally, one goldfish should be kept in at least 20 gallon tank with 10 additional gallons added per extra fish. The filter should be rated for at least twice the water volume. Aquarium salt (NOT table or Epsom salt) can be used as a general tonic to reduce stress, increase gill function, treat minor infection and aid in recovery. Dissolve 1 tablespoon of salt per 5 gallons of water in a cup or two of tank water and gently pour it into the tank. Treat fro 10-14 days then reassess the condition. Partial water changes can be done afterwards to reduce salinity.

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