5 Ways to Save a Sick Fish

If a fish in your aquarium is sick, try doing a water change. You could also change their food or remove certain items from the tank.

May 18, 2024By Colt Dodd
ways to save sick fish

After discovering a sick fish in your aquarium, you may fear the worst: having to flush them down the toilet. However, you don’t have to host a fish funeral just yet. You have many options when attempting to save or rehabilitate a sick fish.

While not a guarantee, even something as minor as doing a partial water change could save your fishy friend’s life. Here are some ideas for attempting to save a sick fish. Many of these tips double as great ways to maintain a well-balanced aquarium.

Recognizing the Sign of a Sick Fish

sick goldfish together
Image credit: Wikimedia Commons

While fish don’t need as much interaction as dogs and cats, they need a fair amount of maintenance to survive. Like any living thing, they need adequate nutrition, enrichment, and the right habitat. If any of these factors go awry, you could find your fish belly-up sooner than you think.

By understanding the signs of a sick fish, you can take action to save their life. These signs include:

  • Gasping for air near the water’s surface
  • Discolored gills or scales
  • White spots on the body
  • Rotting fins
  • Bulging eyes
  • Swimming upside down
  • Leaning heavily to one side

It’s a fact of pet ownership that some fish require stricter water parameters than others. For instance, if you bring home a catfish that you caught, they can thrive in murky, untreated water. Yet, other aquatic creatures (like axolotls) need treated water at just the right temperature. That’s why it’s important to do your research prior to setting up a fish tank.

1. Test the Water Parameters

guy testing water level
Image credit: Wikimedia Commons

A tank’s water parameters refer to the chemicals present in a fish tank or another aquatic set-up. Some fish have different water parameter needs than others. If you have a sick fish, go to the pet store, and buy a water chemical-testing kit. Then, use its instructions to test your tank’s water, and see where things are going awry.

These tests examine a tank’s:

  • pH levels. pH levels refer to how acidic or alkaline a tank is. You want the water to be neutral, with the pH between six and seven.
  • Ammonia. Ammonia is toxic to fish—and yet it’s produced through their waste. If there’s too much ammonia, consider getting a better water filter or doing a water change.
  • Nitrites and nitrates. High nitrite and nitrate levels can spell disaster for an aquarium, as it can be toxic to fish in high levels.
  • Carbonate hardness (KH). The ideal level is 6.5 to 8.0 dKH.
  • General hardness. Too much magnesium, calcium, and metal ions can make water “hard.” The range for most fish species is between 3 and 20 dGH.

2. Change the Water

cloudy fish tank
Image credit: Wikimedia Commons

Changing your aquarium’s water is essential to keeping a clean fish tank. As a rule of thumb, you could remove and replace 25 percent of a tank’s water once every two to four weeks. Depending on whether you have a big tank or a small aquarium, this procedure could take a few minutes or a few hours. Some tips for doing a partial water change include:

  • Being conservative about how much you remove. A fish tank is a well-balanced ecosystem. Removing all the water also removes some of the helpful bacteria that help fish thrive.
  • Keeping the fish in the tank. You don’t want to stress out your fish, plus there’s no benefit to keeping them elsewhere during the water change.
  • Using dechlorinator for tap water. Tap water in many areas contains trace amounts of chlorine, which is harmful to fish. Use a dechlorinator beforehand to make the water less abrasive.

Also: if you’re going to use tap water, let it set out for three days. That way, it’ll lose many of the chemicals that make it too harsh for some fish.

3. Remove Certain Tank Decorations

goldfish in tank
Image credit: Wikimedia Commons

It’s tempting to see a fun little toy or bauble, then put it in your fish tank. Yet, these items can have paint and other materials that can leech into the water, throwing off its chemical balance and poisoning your fish.

If you suspect that a decoration is causing your fish to become ill:

  • Test the water parameters
  • Write down their levels
  • Remove the object
  • Do a partial water change
  • Test the water parameters daily
  • Review your findings

If the tank’s chemical levels stay the same, the decoration might not be the culprit. If the decoration was causing the problem, be sure only to use decorations that are sold at local pet stores in the future. Even though they can be a bit pricey, there’s a reason.

4. Change Your Fish’s Food

fish tank with plants
Image credit: Wikimedia Commons

As you form a bond with your pet fish, you may want to feed them human food. Yet, the flakes or pellets available for purchase offer the vitamins and minerals that fish need. Resist the urge to feed your fish:

  • Bread. You may see people feeding fish bread at lakes and ponds. Yet, bread contains yeast, which can expand in a fish’s stomach and cause distress.
  • Meat. While some betta fish enjoy the occasional earthworm, putting steak, chicken, or pork in your aquarium can throw off the water’s chemical balance––causing your fish to become sick.
  • Dog food. Dog food is for dogs. Even if your fish grows bigger after eating some kibble, this could be a sign of bloat, not a well-fed pet.
  • Crackers. There’s nothing wrong with the occasional treat for your fish. Yet, crushed crackers can soak up water and damage the tank’s parameters. It also has no nutrition for fish.

If you occasionally drop frozen vegetables into your aquarium, remove them the next day if not eaten. You don’t want them decomposing, as this can generate harmful ammonia.

5. Consult an Aquatic Veterinarian

purple betta fish
Image credit: Wikimedia Commons

Aquatic veterinarians exist! And many understand how to save sick or dying fish. During their examination, they may test the tank’s parameters, examine the fish’s gills, and offer medications for antifungal infections. You can find a professional in your area by consulting the American Association of Fish Veterinarian’s website.

Colt Dodd
By Colt Dodd

Colt Dodd is a sighthound enthusiast with three years of freelance writing experience. He has an Italian greyhound/Shetland sheepdog mix named Homer. In his spare time, he enjoys going to dog parks and writing fiction.