You guessed it:

If you want healthy, happy fish, their water has to be suitable for the species you are keeping.

And goldfish have their own set of needs for them to thrive.

So today I’m going to give you the ultimate “cheat sheet” for goldfish water parameters!

But WAIT:

How to know your tank’s unique water parameters?

(It’s not much use to know the correct parameters if you can’t tell if your tank is on point or not!)

Testing Your Water

So:

The simplest way to get a beat on your aquarium’s water is with a test kit.

A good test kit will cover the following “big 5” parameters:

  • Ammonia
  • Nitrite
  • Nitrate
  • pH
  • KH & GH

You can use a liquid kit or a dip strip test.

Either one will do the job. 

I actually have (and use) both kinds so I can compare the accuracy to each other.

But of the two, I think the strips are my favorite.

Way faster to use…

… And also quite accurate, as long as you’re getting a reliable brand.

But the good part about the liquid kind is it is generally more precise – especially when measuring nitrate.

Now:

Time for the goldfish water parameter lowdown!

The “Big 5” Essential Parameters to Test

1. Ammonia

What it is:

Ammonia is a waste by-product of goldfish respiration and poop.

It can burn the gills of the fish, cause stress and even death.

What it should test:

Your ammonia reading should always be at 0.

Any amount greater than that?

Possibly can stress the fish.

In a cycled tank with sufficient filtration, ammonia should only be present in unusual situations, such as if a fish dies.

Ammonia Poisoning Symptoms:

  • Scratching/fin flicking
  • Surface gulping
  • Pale coloration
  • Fin splits
  • Clamped fins

“Help, my ammonia is greater than 0!”

Common Causes:

  • An uncycled tank (new tank syndrome)
  • Insufficient filtration
  • Bacterial die-off from overcleaning
  • Overfeeding, or
  • A combo of all of the above

What You Can do: 

  • Perform large water changes (50% daily at least) to reduce the ammonia to 0
  • Add Seachem Prime to bind the ammonia
  • Test the water regularly and perform more water changes as needed
  • Assess your filtration setup
  • Carbon can also be used to bind the ammonia
  • Please check the tap water to ensure the ammonia is not coming from the tap

2. Nitrite

What it is:

Nitrite is even worse than ammonia as it is more toxic.

It is the result of bacteria turning ammonia into nitrite.

It can cause brown blood disease in goldfish, along with other damage to the gills and skin.

What it should test:

Nitrite should also remain at 0 in the goldfish tank.

Higher than that can cause health issues and even death to the fish.

Nitrite Poisoning Symptoms:

  • Red body marks
  • Red fins
  • Flashing
  • Red belly (advanced)
  • Open gills

“Help, my nitrite is greater than 0!”

Common Causes:

  • An uncycled tank (new tank syndrome)
  • Insufficient filtration
  • Bacterial die-off from overcleaning
  • Overfeeding, or
  • A combo of all of the above

What You Can Do:

  • Perform large water changes (50% daily at least) to reduce the ammonia to 0
  • Add Seachem Prime to bind the Nitrite
  • Test the water regularly and perform more water changes as needed
  • Assess your filtration setup
  • Carbon can also be used to bind the nitrite

3. Nitrate

What it is:

Nitrate is FAR less toxic than ammonia or nitrite.

When you see nitrates, your cycle is near to or fully completed.

What it should test:

For goldfish, it is recommended to keep nitrate levels at 30ppm or under.

Nitrate Poisoning Symptoms:

  • Buoyancy issues
  • Bulging veins
  • Appetite loss
  • Lethargy

“Help, my nitrate is greater than 30ppm!”

Common Causes:

  • Incomplete denitrification + not enough water changes
  • Overfeeding

What You Can Do:

  • Perform several small water changes (25% daily) to gradually reduce nitrate
  • Add live plants to the tank

4. pH

What it is:

pH measures how acidic or alkaline the aquarium’s water is.

A pH of 7 is considered neutral.

What it should test:

Goldfish generally do best at a pH between 7-8.

Too low of a pH burns their skin and can harm the bacteria in the filter.

Low pH Symptoms:

  • Gasping and/or hanging at the top of the water
  • Reduced activity or lethargy
  • Suppressed appetite
  • Excess slime production
  • Slime coat shedding
  • Death

“Help, my pH is too low!”

Common Causes:

  • Nothing to stabilize the pH in aquarium combined with no water changes
  • Low from the tap water source
  • Distilled water

What You Can Do:

  • Perform water changes
  • Add crushed coral to the aquarium (1/2 C per 20 gallons)
  • Do not use distilled water unless it is remineralized

5. KH & GH

What it is:

KH and GH can be used to determine the stability of your pH and how hard or soft your water is.

What it should test:

Goldfish like a KH between 50-120ppm…

… And a GH between 100-300ppm.

Off KH/GH Symptoms

This doesn’t usually cause immediate problems with the fish’s health, but can result in other problems with the water. (Source)

“Help, my KH or GH is too low!”

Common Causes:

  • Nothing to replenish the KH or GH in the aquarium
  • Low from the water source

What You Can Do:

  • Utilize crushed coral (or something like it) at a rate of 1/2 C per 20 gallons
  • Perform a water change
  • Avoid distilled/soft water if possible

The 3 Good-To-Know’s

These parameters can be useful to know, but in most cases are not essential to test.

1. Chlorine & Chloromines

Chlorine and chloromines are added to tap water to keep them free from harmful bacteria that could make people sick.

But to fish, these chemicals are toxic.

Using a dechlorinator that removes chlorine and chloromines is almost always required when you use tap water.

At proper dosage, it usually isn’t necessary to test for these.

But if you are worried about high chlorine levels from your water that might be too much for the amount you’re dosing with dechlorinators, a test can give you some peace of mind.

2. TDS

TDS stands for total dissolved solids.

TDS is a combined measurement of many things in the water – including organic material, inorganic salts (such as calcium and magnesium) or chemicals the water has been treated with.

For goldfish, it is recommended to keep it below 250.

If you keep snails, a higher TDS is usually better for them.

You can use an inexpensive TDS meter to check.

I use this one.

3. Salinity

Salinity is especially useful to know when adding salt to the water, typically when treating your fish for illness.

Too much salt can cause issues for goldfish though…

… And measuring it all out with a grams scale can get confusing (especially if you later have to change the water.)

Salinity meters can help with that by giving you an exact reading in percentage on-demand.

The downside is they can be pretty costly.

But in some situations, they can be very useful.

Salt creep can happen in freshwater aquariums that contain trace amounts of salt but is never changed and only topped off.

Testing the salinity can help prevent this problem and let you know when a water change is required.

Good news:

It generally is not a problem we goldfish keepers have to worry about.

Wrapping it All Up

So now you know the proper and most essential water parameters for goldfish…

… As well as a few extras.

I hope this information was helpful to you.

And of course:

I invite you to share this article with your friends if you know someone who is new to goldfish keeping or is struggling with their water parameters.