fish keeping mistakes

10 Beginner Fish Keeping Mistakes and their Ultimate Solutions

Fishkeeping is exciting and entertaining. Most of the beginners get quite overwhelmed and make a lot of fish keeping mistakes.

There are certain complicated things that beginners don’t understand including conditioning the tank, or feeding the fish properly. Moreover, cleanliness and maintenance are essential and critical.

So, in that case, most of the fish keepers lack skills and they ultimately commit mistakes.

Before starting this hobby as a beginner one must go through this list of most common fish keeping mistakes.

This article will help all the beginners as well as other fish keepers to excel in this hobby. Understanding the problem and knowing its solution is of ultimate importance for your fish’s health.

So, let’s continue.

Here are Fish Keeping Mistakes

Getting the tank before deciding the fish

The very first mistake that most of the beginners make is getting an aquarium without even deciding the fish they want. As we have mentioned in every single article that every fish requires certain tank space. Some beginners see a second-hand tank for a cheap price and they can’t resist it. In such a moment of a hurry, they usually ignore the fact that which fish are they opting to adopt.

For examples, a koi fish requires tons of space regarding its speedy growth, so a 40-gallon tank will be sufficient. But if the tank that you have bought beforehand is 20 or 30 gallons, then your fish’s growth will be restricted.

Avoiding this situation

In order to avoid this situation, you should first decide which fish you want as a pet, then do detailed research regarding that fish. Once you know the basic requirements of your fish you are good to go.

Selecting a suitable tank is a great favor you can do your fish. Thus, for a koi, a 40-50 gallons tank or an open pond will be great. It will accelerate its growth and maintain good health as well.

Buying the fish and aquarium together

Next on the list of top 10 fish keeping mistakes is buying aquarium and fish together. when most of you know which fish to pick and what size of aquarium is appropriate, you think that now is the time to buy the tank and fish as well. Here the problem arises.

Once you have bought the fish you can’t keep it in the packing for longer than an hour. Thus, you need to put the fish in water instantaneously. Doing this will put your fish’s health in quite a danger.


 As it is ruled to purchase the tank at least 2 weeks before getting the fish. This will give you enough time to accomplish the following protocols.

First, you need to clean the tank several times. As the acrylic or glass contains lots of chemicals that can be harmful to your fish. Thus, proper cleaning is necessary.

Secondly, you need to condition the tank. Most beginners have no idea regarding conditioning; well, it means growing a population of nitrogenous bacteria and microbes. These nitrogenous microbes are necessary to dissolve the nitrogenous waste later.

Choosing the wrong location

Once you have purchased your fish and your aquarium as well, its time to select the spot where to put it. Mostly, we prefer to put it at a place where it is protected and prominent.

Most of the people keep their aquarium in the drawing-room or living room or spaces like that, but we forget the basic factors that matter. Because of our lack of information, we end up picking out the wrong location. The wrong location puts a lot of stress to your fish.

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In the case of planted aquarium location even matters more. As they need appropriate light and CO2. Thus, knowing the right place for your aquarium ad the factors that matter is essential.

How to avoid this problem

First of all, you should avoid direct sunlight, as fish don’t need light but excessive light can give them stress. Moreover, for a planted aquarium, excessive sunlight can lead to tremendous algae growth.

This outburst of algae is harmful to plants as well as the fish as it uses up all the nutrients and oxygen leading to the death of both your plant and fish.

Furthermore, cold places should be avoided, as they can lead to a decline in the temperature of your tank. Some beginners keep changing the location of their tank to determine the best one.

Not only it is troublesome, but it can damage your fish too. As it gives lots of stress and it takes much time to settle down and feel comfortable.


As we talking about fish keeping mistakes we can’t simply ignore this common mistake. Some enthusiasts wish to keep lots of fish at a time. In this pursuit, they undervalue the fish’s needs. Beginners commit this mistake quite often. For example; a 40 gallons tank is sufficient for a pair of angelfish, so you shouldn’t add any other fish to this tank.

This overcrowding can lead further to a whole new world of problems. Congestion can lead to stress and restricted growth and bad health. Moreover, fishes don’t get enough space to move around or play.

How to avoid overcrowding?

To avoid this mistake, keep in mind your desired fish, its tank requirements and your tank’s capacity. Furthermore, keep the growth factor in mind as well. It requires complete research regarding every fish you keep.

Additionally, beginners should prefer keeping a lesser number of fish at first. Lesser the crowd, easier it is to maintain. More the fish, greater the mess, harder it is to clean.


Another One form most frequent fish Keeping mistakes is overfeeding. In order to determine the food requirement of your fish, you should keep in mind that fish don’t have a stomach. Beginners usually commit this mistake and end up killing their pet. Lately, overfeeding is the largest cause of fish death in home aquariums.

This problem basically occurs because the fish always seem hungry and as long as you keep feeding, they will keep eating. Overfeeding leads to the two most common diseases in fishes.

Both the above-mentioned disease can eventually result in your fish’s death. Moreover, the more your fish eat the more is the waste in your tank and the more it is harmful to your fish. As this filthy water can cause breathing difficulty for your fish.

Avoiding overfeeding?

To avoid overfeeding your fish remember the “rule of thumb”. It means that give your fish as much food that your fish can easily finish in 3-5 minutes. Some smaller species should not be fed for longer than 1 minute.

Furthermore, feeding your fish a few times a day can be a good option. This gives them time to digest the food and it causes less waste disposal and it can be quickly cleaned. Thus, feeding in small portions can benefit your fish more.

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Choosing wrong Tank mates

For those stepping for the very first time in the world of fishkeeping, this mistake is fairly common and justified as well. Most of the beginners consider that all fishes are friends to each other and live in harmony toward.

Keeping Oscar fish and goldfish together will make it harder for the goldfish to survive. Oscars are known for their territorial nature and if the other companion is a small fish like goldfish then the game is already over because goldfish is finished.

Thus, knowing the nature and compatibility of each fish is of prime importance. Moreover, certain fish species can’t get along with their own type like betta. Bettas love to stay lonely and they avoid their own kind. Thus, keeping a pair of bettas could also prove troublesome.

How to avoid this problem?

To prevent yourself from making such a mistake, give good research to every fish that too ought to keep. Understanding their behavior, nature and instincts. Furthermore, try to compile a list of favorite tank mates of every fish.

For example; in the case of betta fish its favourite tankmates are Cory Catfish, Harlequin Rasboras, Neon Tetras and Celestial Pearl Danios.

You can get all this information from pet stores and online as well. Some pet stores even provide you with a complete list of suitable companions for your desired fish.

Skipping the conditioning process

Another one from these common fish keeping mistakes is skipping the conditioning process.

Mostly, due to lack of knowledge or out of excitement beginners end up making this mistake. Understanding the cycling process and nitrogen cycle is key to better health of your fish.

For the conditioning process, you should get the aquarium at least 2 weeks before getting your desired fish. Conditioning means establishing a community of nitrogenous bacteria.

 These bacteria work by degrading the nitrogenous waste of fishes to nitrite and then to nitrate. Then this waste in the form of nitrate is remover by the filtration system.

If your tank is not conditioned properly, there is no way your tank can stay clean and free from waste. Exchanging a certain amount of water will be beneficial.

How to avoid this problem

Skipping the conditioning procedure can put your fish’s life in danger; thus, you should be vigilant regarding this step.

No conditioning leads to no nitrogenous bacteria that leads to increased waste and eventually death of your fish.

In order to prevent this from happening condition your tank at least two weeks prior to adding fish.

Moreover, a change of at least 10-25% of the water every week. This is the best way to keep your fish tank free of any waste and your fish safe from any danger.

See our other article on Aquarium Setup for beginners | A complete guide

Using tap water for aquarium

One major misunderstanding that occurs in the minds of the beginners is that tap water is appropriate for your aquarium. Always remember that tap water is full of impurities that can even prove fatal for your fish.

Tap water is chlorinated and contains a tremendous quantity of chloramines, nitrate and nitrite. These harmful chemicals make it difficult for fish to breath properly. Moreover, this tap water could be hard to super hard in quality having hardness between 25-45 dH.

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Thus, using tap water is an absolute no unless you want to see your fish sick.

How to avoid this mistake?

Thus, from the very beginning try using filtered water. Filtered water is free of chlorine and other harmful chemicals. Moreover, it is treated in a way to decrease its hardness.

Furthermore, before adding water in your tank always make sure that it has the right pH, suitable hardness and 0ppm of chlorine, nitrate, nitrite and ammonia. Using biological media is the best solution.

Ensuring accurate water parameters is necessary for survival and healthy growth of your fish.

Replacing all the water while cleaning

One of the most commonly committed mistakes is replacing all the water at once. This could prove fatal for your fish.

Changing 100% can lead to the removal of all the beneficial nitrogenous bacteria and microbes necessary for the healthy survival of your fish.

If there are no such bacteria available the nitrogen cycle will be destroyed and your fish’s health will be in grave danger because of excessive waste build-up.

Avoiding this mistake?

To prevent this from happening, set up a time table for cleaning your tank. After every week clean your tank and replace at least 10-25% of the water every time.

 Replacing a certain amount of water will maintain a suitable quantity of nitrogenous bacteria and will also keep your tank clean at the same time.

Choosing the wrong substrate

Choosing the wrong substrate is the most common problem that beginners make. As it requires tons of experience. Moreover, it requires information regarding every fish type.

For example; in a planted tank, you should prefer some soft substrate containing essential nutrients. At the top of soft substrate use gravel substrate to top it off and that will give a better grip to plants and nutrients.

Furthermore, for bottom dwellers, you should use soft substrate like sand to help them play around. If instead of that a hard gravel substrate is used it will harm your fish.

Thus, selection of a suitable substrate is pivotal. A wrong substrate not only gives additional stress to your fish and also makes the fish ill and affect its growth.

How to avoid this mistake?

To select an appropriate substrate for your aquarium first do a little research on types of substrates and its uses. You can also get some information regarding different substrate from the pet stores.

As for the natural aquascaping, you need a 2-3-inch layer of soft sand substrate (inert or active) with a layer of carpeting plants to provide the best natural environment to your fish.


I hope that these solutions will prevent you from making any further mistakes. To avoid any mistake, try getting detailed information regarding every single fish.

 These Fish Keeping Mistakes can be dangerous for your fish life. Overfeeding and skipping the conditioning process are the two most deadly mistakes you can make.

Lastly, remember that mistakes are a part of the learning process. thus, never give up on this amazing hobby and you will enjoy a lot.

Tell us in the comment section if you ever made any of these mistakes?

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