10 most common mistakes of beginners make with goldfish

mistakes of beginners make with goldfish

Nobody is perfect, we all make mistakes, especially when we start a new hobby. The common mistakes of beginners make with goldfish when they start with their beginning! This list is intended to help new owners of goldfish.

Here you will find, in disorder, 10 most common mistakes of beginners make with goldfish.

10 mistakes of beginners make with goldfish

We do not throw stone at anyone, we all went through square one, and we all made almost identical mistakes. Ideally, everyone should take information before acquiring their first goldfish (or any other animal). How to take care of goldfish, what is its ideal habitat, how to feed it properly, discover the basics of maintaining an aquarium … but popular beliefs (goldfish = jar, goldfish = robust …), combined with bad advice in some pet shops, make that often we start by buying goldfish and improvise thereafter as and when concerns.

We learn to take good care of his goldfish over time, learning from our mistakes, communicating with enthusiasts who will advise you.

Mistakes # 1: Buy a jar or a very small bin

mistakes of beginners make with goldfish

The 1st mistakes of beginners make with goldfish try to keep a fishbowl. You must never keep goldfish in a small fishbowl or jar. The goldfish, which live on average 8 to 10 years, become large and grow quickly when they have very comfortable living conditions. In addition, they need a lot of space to swim, so a fairly consistent length. They also produce a too much waste, which means that you need a lot of water to dilute their waste and a large colony of good bacteria to naturally turn waste into less harmful products. All this is only possible in an aquarium of at least 60 liters.

Want to know how many goldfish can be kept in your aquarium? A single goldfish needs at least 50 liters.

Mistake # 2: Feeding too much your fish

Feeding too much is other mistakes of beginners make with goldfish. They digest like ducks, that is to say, that they eat and that the droppings arrive less than 5 minutes later. The goldfish look for food all time, its main activity, you could virtually give it food every hour. For this reason, you should feed your goldfish in small amounts several times a day, rather than giving them a lot of food at one time. Too much food can cause both constipation and swim bladder problems (fish floating on the belly in the air).

The goldfish eat a lot and it is a big fish, so it pollutes a lot of water. Many feeds, much more maintenance, water change and disease risk.

Mistake # 3: Put too many fish in the aquarium

mistakes of beginners make with goldfish

Goldfish need a lot of space and can cloudy the water quickly. You must, therefore, be careful not to put your aquarium in overcrowding. The more goldfish there are, the more the maintenance becomes rigorous and frequent. Remember 50 liters of water per goldfish. Overcrowding is often the cause of illness and death in the aquarium.

Mistake # 4 Do not use filter or filter too small

An aquarium must have a good filter that will work 24 / 24h, it is the heart of the closed ecosystem that is the aquarium. As mentioned earlier, goldfish produce a too much waste, which cloudy the water in their aquarium. The filter houses and maintains a colony of good bacteria that degrade fish waste to make them almost innocuous. Sometimes we use an aquarium filter sold with the aquarium, but they are still insufficient capacity for your fish tank, the filter must have a water flow of 5 times the volume of the fish tank per hour.

Mistake # 5: Do not cycle the aquarium

This is a very common mistake among people who take a goldfish on a whim, or who earn a goldfish at a game. The goldfish produce a lot of waste and therefore ammonia, which is very bad for them, it burns the gills. Fortunately, there are “good” bacteria that can convert this ammonia into less harmful elements. Before you even buy your goldfish, you must start and stabilize the biological “cycle” of your aquarium to build a colony of these good bacteria.

Mistake # 6: Do not make water changes regularly

mistakes of beginners make with goldfish

Generally, you must change some of the water in your goldfish once a week. This change of water should be as regular as possible, the amount in liter and the frequency depends on the size of your aquarium. The bigger the aquarium, the less maintenance there will be.

A water change of 50% is also essential in some cases, for example, if you find in doing your tests a nitrite peak (see also our article on water parameters).

Mistake # 7: Changing too much water at a time

You do not have to change all the water in your goldfish at one time. The equilibrium of the water parameters of the aquarium is fragile, changing all the water causes a strong stress in the fish (risk of diseases). again by filling the aquarium again, your goldfish will be “dipped” in iced water at the tap outlet. We suggest regular water changes of about one-third of the volume of the aquarium each week. Use an aquarium siphon to drain the water and suck up your gravel at the same time, eliminating waste from your tank.

Mistake # 8: Too clean the filter, gravel, and decorations

Your filter foams, gravel, and decorations all host good bacteria without which your aquarium would not be suitable for the maintenance of goldfish! NEVER clean up, wash your filter, filter foam, gravel and decorations on the same day and with tap water! Remove a bucket of water from the aquarium and use it for cleaning the elements. Simply rinse the foams from your filter, do not replace them every week.

Mistake # 9: Do not quarantine new fish

The new goldfish can sometimes carry disease, which spread to your other fish already in place in the aquarium. That’s why you do not have to add them to your main aquarium right away. Only a “quarantine” precaution can prevent you from losing your goldfish. All new fish must be separated from the others for two weeks, in a temporary container, time to ensure that they are in good health and that they have no diseases, such as white dots, or fin rot.

Mistake # 10: Do not use real plants

mistakes of beginners make with goldfish

For practical and maintenance reasons many beginners prefer to decorate the aquarium with plastic plants. In addition to the aesthetics of plants for the human eye, plants have a role to play in the eco-system of the aquarium. They are essential, to slow down the appearance of algae, for the filtration of the aquarium, for the homogeneous oxygenation of the water.


If you are new aquarist and you try to keep goldfish, so avoid this common mistakes you’re beginning fish keeping, and try to best for your favorite fish’s healthy life.

If you think we have forgotten something important mistakes of beginners make with goldfish, or if you want to share your own mistakes, then leave a comment below.

Roman Walker

Author: Roman Walker

Roman Walker has been obsessed with fish since he can remember. From his first goldfish to his current elaborate saltwater setup, Roman loves learning about and caring for aquatic creatures. He's excited to share his passion and knowledge through this blog.

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