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How to save my sick freshwater fish after an ammonia spike?

Updated On September 23rd, 2025

Pet's info: Fish | Freshwater Fish

Two of our freshwater fish are acting oddly in the water. We did lose a few last night, due to an ammonia spike. We noticed some pale-colored, wormlike flesh dropping from the front area (between the mouth and front fins); this black Guppy is “wobbling” around... We also have an orange Molly fish that has been staying on the bottom, not eating or moving much. Attached are pics, for your review. Can you please provide advice for these issues, we want to try our best to save them!

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2 Answers

Most Helpful Answer

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on June 22nd, 2019

Monitor water chemistry using 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 partial water changes to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. Pristine water quality is the foundation for healing and recovery from infection or injury in fish. You can use plain aquarium salt (NOT table or Epsom salt) as a general tonic to reduce stress, improve gill function and aid in recovery. Dissolve 1 teaspoon of salt per gallon of water in a cup or two of water and gently pour it into the tank. Treat for 14 days then reassess the condition. An "all in one" product, such as Lifeguard (by Tetra), can be used concurrently to treat infection or parasites. Find one in the aquarium section of the local Petco. Follow label directions carefully and remove the carbon filter insert during treatment if indicated.

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    Answered By Todd Cecil

    Veterinarian

    Published on

    Thanks for reaching out about your fish. Correcting the water quality is the most important thing, whether adding beneficial bacteria or water changes. Ammonia can cause abnormal behavior, decrease the immune system allowing secondary infections and even death. A local veterinarian might be able to perform a necropsy and determine a cause of death. Good luck.

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