15 Mistakes Beginners Make with their Goldfish Tank (How to avoid them)

Goldfish are very easy to maintain fish.

Thinking the same, I decided to select Goldfish as my first pet fish.

But you know what, I was wrong!

Yes, Goldfish is a pretty hardy fish compared to other fish.

But the reality is, you just can’t get a fish tank, fill it with tap water, throw your Goldfish in it and forget about it.

It just doesn’t work like that!

When I look back, in my several years’ experience of Goldfish keeping, I realize that there are 15 mistakes that most beginners make with their Goldfish.

So in this article, I am going to address the same mistakes and how you can avoid them.

So let’s get started.

15 Mistakes Beginners Make with their Goldfish Tank

1. Not Cycling the Aquarium Before Putting the Goldfish

This is probably the most deadly mistake that can cause the death of your Goldfish.

When you decide to get your first aquarium, you are very excited.

You want to put your first fish into that empty aquarium ASAP.

But you must first cycle your aquarium before putting your Goldfish into it.

Why it is so important to cycle your tank?

The thing is, Goldfish don’t have toilets in their aquarium.

So they poop and pee while they are swimming in the tank.

And if you don’t cycle the tank then this poop and pee will release ammonia which is deadly for your fish.

So to cope with this problem you have to cycle the aquarium.

The nitrogen cycle basically creates beneficial bacteria in your aquarium that break down the ammonia into nitrite and then into nitrate which is far less harmful to your fish.

So be sure to cycle your aquarium before introducing your Goldfish into it.

2. Choosing a Fishbowl or Small Tank

I have seen many Goldfish keepers make this mistake. 

We usually see in movies, on TV, and on the internet, Goldfish are usually kept in a fishbowl.

But in reality, it is not a good place for them.

A fishbowl and even a small tank don’t provide an optimum environment for the proper growth of Goldfish.

In fact, a single Goldfish require about 20 gallons of water for its proper growth.

Or if you have a small Goldfish then 5 gallons per inch is a good rule to follow.

Why Goldfish require a large tank?

Goldfish can grow very big and they are quite messy fish that can produce a lot of ammonia, that’s why for their proper growth you require a large tank for the Goldfish.

3. Overstocking

This mistake is related to the above mistake which is using a small tank or fishbowl for your Goldfish.

As mentioned above, a single Goldfish require 20-gallon water for its optimum growth and if you have a small Goldfish them 5 gallon per inch is a good rule to follow.

So, if you keep a lot of Goldfish in a small tank then it will not be beneficial for your Goldfish’s growth.

Their growth will be stunted and as Goldfish are very messy fish the ammonia level in the tank will rise that can cause the death of your Goldfish.

So don’t put a lot of fish in a small tank.

4. Not Dechlorinating the Tap Water

This is very common mistake beginners make when they are just starting out in this hobby.

Chlorine is very harmful to your Goldfish.

It causes a disease known as acute necrosis in fish.

Chlorine kills the living cells and damages fish’s gills.

It also damages the skin of your Goldfish.

When you put fish into chlorinated water, it will begin to suffocate and suffer from respiratory problems.

So be sure to dechlorinate the tap water before introducing it into your Goldfish aquarium.

Ways to dechlorinate the tap water

1. Pour down the tap water into a bucket that you have never used with any soap or chemicals and let the water sit overnight.
2. You can add dechlorinating agents in your tap water to remove chlorine from it instantly.

Check out our recommended Dechlorinating Agent

5. Placing the Fish Tank at the Wrong Place

This is also a very common mistake. 

Let’s face it, an aquarium is very difficult to move from one place to another.

So you should choose a good place for your aquarium before even buying the aquarium.

There are a few things you should keep in mind while deciding a place for your aquarium.

How to Choose an Ideal Place for an Aquarium?

Can I see it?

Aquariums are meant to see and enjoy. It is very relaxing when you see your Goldfish moving around slowly.

So you should put your aquarium where you like to sit and relax.

Is the electrical outlets and water source nearby?

An aquarium is not just your fish and fish tank. You need to install other equipments like a filter, an air pump, lights, etc.

So make sure that the electrical outlets are nearby.

Also, you need to change the water of your aquarium regularly so it is nice to have your aquarium near a water source.

Check out our recommended supplies

Is the area hot or cold?

Goldfish like a stable temperature of the water for their optimum growth.

If the water temperature changes throughout the day then it really stresses your Goldfish.

So make sure that there are no heating vents or fireplaces nearby your aquarium.

Also, make sure that you are not placing your aquarium near the window so that it will not get directly exposed to the sunlight.

Because it can raise the temperature of your aquarium very quickly.

Also, make sure that your aquarium is not nearby any air conditioning units or vents.

Is there any noise nearby?

Goldfish like to sleep in a quiet and dark environment.

So you should not put your Goldfish near any sound source like speakers. It can disturb your Goldfish.

6. Not Maintaining Optimum Oxygen Level in the Aquarium

Not only Goldfish but any fish require an optimum amount of oxygen in the fish tank for their proper growth.

If you don’t have a sufficient amount of oxygen in your aquarium then your Goldfish can suffocate and it can cause various respiratory diseases.

Maintaining an optimum amount of oxygen in an aquarium is critical.

Signs Your Aquarium has a Low Oxygen Level

• If you noticed your Goldfish coming on the surface of the water gasping for air frequently then it is a sign that your aquarium has low oxygen.
• If you noticed rapid gills movement in your Goldfish then it is suffocating and trying to get oxygen.
• If you noticed your Goldfish is moving around less then it is a sign that your aquarium has a low oxygen level. But don’t get confused with sleeping Goldfish. Goldfish don’t have eyelids so their eyes open while they are sleeping. Also, they don’t sleep like us lying on the surface. Instead, they hover over the water while sleeping.

If you noticed any of these signs then your aquarium has a low oxygen level and there are several ways to increase oxygen in an aquarium.

7. Feeding the Wrong Food

Goldfish food is different from other fish food.

Goldfish food contains a relatively low amount of protein and a high amount of carbohydrates in it.

So, choosing any generic fish food for your Goldfish is a bad idea.

You should choose fish food that is made for Goldfish.

Usually, the food for your Goldfish comes in two forms, flakes and pellets.

Flakes float on the surface of the water and pellets sinks into the fish tank.

But there are some varieties of pallets that also float on the surface of the water of your fish tank.

In their natural habitat, Goldfish feed on small insects, larvae, and plants as well.

Goldfish are omnivorous scavengers, so you should feed them both vegetarian and non-vegetarian food.

Flakes and pellets fulfill their non-vegetarian diet.

To fulfill their vegetarian diet you can feed them vegetables like peas, spinach, and fruits like apples, blueberries, and grapes.

Besides flakes and pellets, you can also feed them bloodworms and brine shrimp.

When it comes to food for your Goldfish there are two options available which are live food and dried food.

Obviously, live food is healthier than dried food.

But it also has its own drawback which is, it can transfer disease into your Goldfish.

To avoid this problem I would suggest you go for dried food. 

It is still very nutritious for your Goldfish and most importantly it doesn’t have any risk of transferring the disease.

8. Overfeeding

This is a very common mistake new Goldfish owners make.

Goldfish look like they are always hungry and they will entice you to feed them.

But feeding your Goldfish over and over again is a big mistake.

Goldfish don’t have stomach and overfeeding them can cause even death.

So how much should you feed your Goldfish?

Basically, there are two rules you can follow

1. Feed your Goldfish the amount of food equals to the size of their eyes.
2. Or you can feed your Goldfish the amount of food they can consume within 2 minutes.

Follow any one of these rules and stick with it.

Also, you should not feed your Goldfish more than two to three times per day.

9. Putting Wrong Mates with your Goldfish

This is also a very common mistake beginners make and it can cost the death of your Goldfish.

While selecting mates for Goldfish you have to be very careful.

You have to look for the mates which are comfortable with the environment like the water temperature and water pH that Goldfish prefers.

So what are some good mates for your Goldfish?

Ideally, you should keep another Goldfish of the same species and size with your existing Goldfish.

Fancy Goldfish like fantail Goldfish are very slow and delicate compared to normal.

So if you keep them together, raise the risk of malnutrition in Fancy Goldfish.

Also, it raises the risk of overfeeding your normal Goldfish.

If you are planning to put betta or tetras with your Goldfish then it is also a bad idea because betta prefer a warm environment and they can also nip on the fin of your Goldfish.

Cichlids are very aggressive and they are not good for your Goldfish in general.

So what are some good mates for your Goldfish?

As mentioned above, other Goldfish of the same species and size are ideal for your Goldfish as mates.

Besides, there are few others that can be good mates for your Goldfish like Bristlenose and Rubbernose plecos. 

They are good mates for your Goldfish because they prefer the same environment as your Goldfish requires and they are calm fish in general.

They spend most of their time eating and they feed on algae.

So they will also help to remove algae from your tank.

Snails are also very good mates for your Goldfish.

Snails are a very calm creatures and they feed on algae, so they will help to keep algae in control in your aquarium.

Rosy barbs are also a good fish to keep with your Goldfish.

They look good and they are very calm fish.

And they are quite big fish so your Goldfish cannot eat them because it will not fit into their mouth.

Dojo loaches are also very good mates to keep with your Goldfish because they require the same environment as your Goldfish to thrive.

But you required to keep them into a group of three and they require a large space so you will have to keep them into a large tank.

10. Putting Wrong Plants with your Goldfish

Goldfish are omnivorous scavengers so they feed on both non-vegetarian foods like insects and larvae etc and vegetarian food like plants, vegetables, and fruits.

In their natural habitat, they feed on plants to fulfill their vegetarian diet.

Goldfish like plants in their tank. Sometimes they like to munch on them and it also provides them a place to hide.

Besides, it also offers you a chance to personalize the aquarium and make it unique and interesting.

But as Goldfish like to eat plants, if you put slow-growing plants in the tank, then it will not survive for a long time.

So what are some good plants to keep in your Goldfish aquarium?

There is a decent variety of plants to keep in a Goldfish aquarium.

Anacharis

Image by Christina Cahalane under CC BY 2.0

Anacharis is a very good fast-growing plant.

It is ideal for your Goldfish because it grows pretty fast and even if Goldfish munch on them, they can survive in your aquarium.

Anubias

Anubias plant is also a very good fit for your Goldfish aquarium.

These are especially good if you want to create some contrast in your aquarium because they are a bit of dark green in color than other plants.

Usually, Goldfish don’t like to eat them, so they can survive in your Goldfish tank.

Java fern

Java fern is a floating plant and it requires very little attention which makes it beginners friendly.

Also, they can survive in a high bio load environment which makes them ideal for your Goldfish aquarium.

Java moss

Java Moss also doesn’t require any attention.

this plant can survive in any light condition, so you can put them anywhere in your aquarium.

Goldfish sometimes like to snack on Java moss but if you keep your Goldfish well-fed then they can survive in the Goldfish tank.

Amazon sword

This is a very big plant and if you have a large tank then it is a great addition for your aquarium.

As this plant can grow very big, even if Goldfish munch on it it can survive.

It is a very big plant you should not keep them beside small plants so that other small plants can also get light.

Hornwort

Hornwort is a very cheap plant and you can find it in almost any pet store.

So even if your Goldfish nibble on it, it will not cost you a lot of money.

Besides hornwort has very unique shaped leaves that really look cool.

11. Not Cleaning the Gravel or Substrate

In their natural habitat, Goldfish have gravels.

So putting gravel in your aquarium helps to emulate their natural habitat in your aquarium.

Gravel also promotes space for the growth of the beneficial bacteria that help to lower the ammonia level in your aquarium.

But gravel is also the place where many unnecessary things like uneaten food, Goldfish waste, and decade plants are trapped in.

That’s why you should regularly clean your gravel using a siphon. Check out our recommended Vaccum Cleaner or Siphon

You should clean your gravel once a week or once in two weeks depending on how much waste is trapped in your gravel.

12. Overlooking the Lighting Conditions of your Aquarium

Lighting conditions are usually overlooked by many beginners who started with this hobby.

Maintaining proper lighting is very important for a healthy aquarium environment and proper growth of your Goldfish.

You should not keep the lights of your aquarium on for more than 12 hours because it can promote the growth of algae.

Also, Goldfish like to sleep in a dark and quiet environment so putting the lights off during nights is a good idea.

If Goldfish didn’t get sufficient sleep then it can affect their immune system and raises the risk of causing various bacterial diseases.

If you have planted aquarium then you should adjust the lighting of your aquarium according to the needs of your plants.

13. Not doing a Partial Water Change

Doing a partial water change regularly is a very important practice for maintaining a healthy aquarium.

You should do a partial water change of about 25% of your aquarium on a weekly basis.

Benefits of Partial Water Change

• Partial water change helps to increase oxygen in your aquarium.
• Partial water change helps to keep the water in your aquarium clean.
• Over the period, the water in your aquarium evaporated. Which causes a high concentration of salt and waste minerals in the aquarium. When you do a partial water change it helps to dilute the waste minerals and salt in the aquarium.
• If you noticed the high temperature in your aquarium then doing a partial water change with slightly cold water then it can help to reduce the temperature.
• If you noticed a high ammonia level in your aquarium then doing a partial water change can help to reduce the ammonia level in your aquarium.

Just be sure to dechlorinate the tap water before introducing it into the aquarium.

14. Overlooking the pH Level of Water

Maintaining the ideal pH level is very important for a healthy Goldfish aquarium.

But this factor is usually overlooked by not only by beginners but also experienced Goldfish keepers.

Usually, the pH of the water changes over time.

The ideal pH for Goldfish is 6.0 to 8.0.

But Goldfish can survive beyond this range if the pH raises or decreases gradually.

A sudden rise or decrease pH can cause harm to your Goldfish.

The pH level of the water usually decreases when there is an increase in the carbon dioxide levels in your aquarium.

The pH level of the water usually increases if you put some ornaments or decoration which are rich in calcium like coral sand or tufa rock etc.

So you should regularly track the pH level of your aquarium to see if it is raised or fallen below the range that a Goldfish can tolerate.

If the pH level is decreased beyond the range Goldfish can tolerate then you should do a partial water change to increase the pH.

If the pH level of your aquarium is raised beyond the tolerance level of the Goldfish then you should remove the ornaments which are rich in calcium from your aquarium.

15. Cleaning the Filter Wrong Way

Aquarium filter provides space for the growth of beneficial bacteria which helps to reduce the ammonia in the aquarium.

Most beginners don’t know how to clean the filter of the aquarium and that often causes loss of all the beneficial bacteria.

So, you should clean the filter with aquarium water. This will help to retain the beneficial bacteria.

Or at least clean the biological media with aquarium water and you can clean the other media like chemical and physical media using normal tap water.

Not Keeping Track of the Water Quality

As you can see, there are several factors that come into play to maintain a healthy aquarium environment.

So you should always keep track of the water quality of your aquarium.

To do that, you should always perform several tests to know the ammonia level, pH level and water temperature of your aquarium.

Ammonia test

The best way to keep track of the ammonia level in your aquarium is by using an ammonia test stripe.

If you noticed ammonia in your aquarium is more than 0.2 mg then it is a high ammonia level and very harmful for your Goldfish.

Ways to Reduce Ammonia in the Aquarium

1. If you noticed high ammonia in your aquarium then you should immediately do a partial water change of about 30% of the water. It will help to reduce the ammonia in your aquarium.
2. The ammonia level in your aquarium is usually raised because of the uneaten food, dead or rotting plan,t and fish wastes. And these waste products are usually trapped in the substrate of your aquarium. So to remove such waste products from your aquarium you can use a siphon.
3. If you found any dead fish in your aquarium then you should remove it as soon as possible.
4. A filter provides a place for the growth of beneficial bacteria which helps to reduce or remove ammonia from your aquarium. If you noticed the water is not freely flowing through your filter then chances are it is clogged. So, in this case, you should clean the filter using best practices.
5. If you found a lot of uneaten food in your aquarium then you should cut down on feeding your Goldfish. This will help to keep the ammonia level in control.
6. Goldfish is very messy fish and it requires a lot of space for its proper growth so if you are putting many Goldfish in the small tank then this is most likely the reason your aquarium has a high ammonia level. So you should upgrade to a large tank to reduce the ammonia. 20 gallons for a Goldfish or if you have small Goldfish then 5 gallons per inch of Goldfish is a good rule to follow.
7. You can use chemicals to reduce ammonia in your aquarium.

Water pH Test

The pH of your aquarium water usually changes over time.

And Goldfish are very tolerant to these changes if they are happening slowly.

The ideal pH range for Goldfish is 6.0 to 8.0.

So, you should regularly keep track of the water pH of your aquarium.

Temperature

Goldfish is a cold-water fish and high temperatures can cause nerve damage in Goldfish.

Also, some Goldfish like fantail Goldfish are sensitive to very cold water.

The ideal temperature for Goldfish is 62 to 75 degrees Fahrenheit.

You should maintain the ideal temperature of water for your Goldfish for its proper growth.

If you live in a cold region then you can use a heater to maintain the ideal temperature of the water. Check put our recommended heater.

If you found the water temperature of your aquarium is high then there are several ways to reduce the water temperature.

Ways to Reduce Water Temperature

1. First of all, you should turn off the lights of your aquarium and remove its lid.
2. Then you should turn on the ceiling fan or put a table fan near the aquarium so that the air will blow over the surface of the water.
3. You can also put some ice cube in a zip-closed bag and hang it inside the aquarium to lower the temperature of the water.
4. If your aquarium is directly exposed to the sun-rays then you should move it to a place where it will not get exposed to the sun-rays directly.
5. Also, if your aquarium is in the room where there is a lot of sunlight then this can also raise the temperature in the aquarium. So you should put your aquarium in the room where there is no sunlight or at least very little sunlight.

Conclusion

As you can see there are a lot of places where you can mess up your aquarium.

And these mistakes can cause even death of your Goldfish.

But maintaining a healthy aquarium is not a very hard thing to do.

Once you understand how it all works, it will be very easy for you to maintain a healthy aquarium.