Setting up the first aquarium is a great new experience with a great memory to remember the mistakes you made in the beginning. For a beginner trying to maintain the condition can be challenging, there are lots of mistakes that you can make. And a lot of time these beginner aquarium mistakes are made due to lack of information and experience. There is various information source available online, but you might not always find the right information and right solution for your real life situation.

This article will help you with the most common mistake that you can make and how to avoid them. Avoiding the mistake from your initial day is far easier than trying to fix them at later date.

So, let us discuss some of the most common beginner aquarium mistakes and how can you avoid making them.

Common Beginner Aquarium Mistakes

A Small Fish Tank

Beginner Aquarium MistakesChoosing a small aquarium at the beginning of fishkeeping is one of the most common beginner aquarium mistakes. Many beginners think that small tank is easy to set up and maintain, looks tiny and attractive, but with the small tank or small bowl there enough space for your new fish. Unlike nature’s environment, a fish tank is a closed environment for both fish and the aquarium waste. And if you are not eliminating those waste, you are creating an unfavorable environment for the fish eventually killing them. So, the smaller the tank is the most difficult it gets to create an environment favorable for the fish changing water condition quickly.

You will have to test the water condition daily to ensure you give required perimeter to the fish and you will need to change the water quite often to maintain the water quality. It is also difficult to find the aquarium equipment that fits in the small fish tank without disturbing the fish. The better way to start a new tank is with a large tank. A larger aquarium is far easier to maintain the water perimeters. The best advice is to start with a tank with minimum 30-gallon volume. For detail please view the following article: Fish Tank Setup For Beginners.

Adding Fish Too Soon

This is the most common beginner aquarium mistakes made in fish keeping hobby. If you ask an aquarist their most importing character trait, they will one hundred percent agree with “Patience”, whether it is waiting to add fish or waiting for the nitrogen cycle to complete before adding fish.

You are too much excited to add fish to your new tank and set the tank straight away without any management. Most of them put the fish before the water parameters are stable that leads to early death. It is far better to allow your aquarium and filter to cycle properly for few weeks until the water parameters are stable.

Using Normal Tap Water

Beginner Aquarium MistakesWhen you set up your new aquarium, you usually go for normal tape water assuming it will do just fine, but the water from the tap contains chloride and much other chemical substance that are harmful to your fish. It is always recommended to use mineral water in the beginning and let it stabilize for few weeks before adding your first fish. You should always check pH levels, ammonia, nitrates and water hardness because different fish requires different water perimeters. Always cycle your tank first before adding your fish.


Choosing The Wrong Light

Lighting is very important, for both your aquarium plants for photosynthesis and for your fish. If you don’t provide a good lighting for your plant, your plant will not grow. With the perfect lighting, your fish will be happy, active and reproduce. Always make sure that you use enough lighting during the day and special light during the night that won’t disturb the fish.

Adding Too Many Fish

Beginner Aquarium MistakesOverstocking the fish tank is one of the most common beginner aquarium mistakes that a beginner makes. Overstocking can cause a problem in your filtration system leading maintaining water perimeter near to impossible. If your tank is small and you keep too many fish in the tank it will destabilize the water chemistry and fish may have a problem in small space.

Taking Equipment From Other Tank

You want to set up your tank and in a hurry, you do a mistake, by taking borrowing someone experienced aquarist’s equipment. You never know what disease or infection you may bring to your tank by doing this. So it is better for your fish and tank to use new equipment, sterilized equipment or else, you might see your fish getting sick and unhealthy the next morning.

Constantly Rearranging Aquarium

Repeatedly moving things in the aquarium will stress your fish. Many times you may have a plan in mind or ideas of how your tank should look like when fully set up, and start moving things and replacing decorations. Moving things can actually swing mood of your fish. The thing you can do is use real plants right away rather than using artificial plants first. And replacing it with like plants hassling the fish later.

Feeding Too Much

Beginner Aquarium MistakesThere is a particular time to feed you fish, mostly twice a day in a small amount. Whatever you provide them, they must be able to finish it within 5 to 7 minutes. But there is some type of fish that eats anything you provide them as many times as you feed them. In fact, your fish seems to be always hungry for example Goldfish. As a beginner, you might think your fish is hungry or you may enjoy giving food to them and see how they eat. But, it is unhealthy for your fish. This will also create two major problems inside your tank. First, is your fish will unhealthy and lazy; second, fish waste increases resulting in a toxic environment for your fish.

Using Too Many Chemicals

One of the worst things a beginner will do to their aquarium is using lots of unnecessary chemicals in the tank. And most of the shopkeeper let you buy these chemicals for their profit. You can always create a great environment for your fish naturally without adding any chemicals. And only use chemicals when it’s absolutely necessary.

The two most common reasons we get to hear about chemical use are:

  • To prevent illness
  • to stop growing algae

Both of these can be overcome naturally, with regular maintenance, good water quality, and doing at least 10 percent water change in every three to four days. You usually use Algaecides as prevention but it must be used only if there is algae breakout. Also, you can prevent algae from water change instead of using chemical constantly.

No Maintenance Schedule

Maintenance is difficult only if you do it in a long gap. And many people learn this lesson the hard way. If you do it regularly, this is not as hard as you think. You should have a schedule for maintenance that will help you avoid problems.

Keeping aquarium perfect requires consistent maintenance. Key maintenance activity includes:

  • Water changes
  • Testing water composition
  • Tank and filter cleaning

You should make time for maintenance every week on maintenance.

Not Using Live Plants

Beginner Aquarium MistakesIn the freshwater aquarium, I would consider live plants a necessity, but it depends on your aquarium setup and filtration system you use. Planting live plants helps you to minimize nitrate in your aquarium using it as a fertilizer. Almost all beginner aquarist makes some kind of mistake whether it’s overfeeding or overstocking. Here, the live plant will help to oxygenate the aquarium water. The other benefit of planting aquarium plants is that they help prevent algae, because, they eat the same nutrients.

Not Understanding the Nitrogen Cycle

Nitrogen Cycle is, in fact, the most confusing aspect or topic of fishkeeping hobby for a beginner. It is slightly complex until you get the hang of it. Nitrogen Cycle is not anything too difficult and it’s just something you take in your step. All you need to know about nitrogen cycle is that failing to encourage and maintain the nitrogen cycle will cause the death of your fish. Do follow the following link to learn about nitrogen cycle: How to Start Aquarium Nitrogen Cycle | Aquarium Cycling.

Insufficient Water Changes

As I have mentioned earlier, unlike nature’s environment, a fish tank is a closed environment for both fish and the aquarium waste. And if you are not eliminating those waste, you are creating an unfavorable environment for the fish eventually killing them.

Beginners often neglect this thinking they can get away with an infrequent larger water change. In order to maintain water quality and to keep the aquarium healthy, weekly water changes are crucial. As a general rule, you should do 10% – 15% water change each week.

Lack of Use of Biological Filtration

Beginner Aquarium MistakesMost of the beginner aquarist use an air pump and a mechanical filtration system. Believing it will provide enough filtration in the tank. This is Incorrect. Regardless of the size of the aquarium, you should always have at least a type of biological media in your system. And keep in mind that you should not clean your biological filtration media frequently. It’s almost unnecessary to clean your biological media. Use of biological media will ensure the growth of beneficial bacteria in the media that helps you minimize toxic in your aquarium water.

Also as a tip, if you ever have to clean your biological medium, always use aquarium water and not tap water. Because the chlorine in tap water will destroy your beneficial bacteria which is not ideal.

Mixing Fish

The beginner thinks that every fish is friendly and they all can get along with each other, keeping them in the same tank together. But, this is wrong. First, we have to keep in mind that fish are carnivorous and eat the smaller fish or anything that fits in their mouth. Secondly, you must be sure that different breed of fish are compatible with each other before you keep them in the same tank.

Using The wrong Filtration medium For The Aquarium Volume

Different aquarium filter will have different rating for the amount of water that can run through them. Today’s aquarium filter offers a wide variety of filters to keep your tank’s water clean and healthy. While choosing your aquarium, your decision must be based on the size of the tank, type of fish and number of fish. The turnover rate of the filter should be at least 3 times the volume of aquarium per hour. For example, if your aquarium is 20 gallon then you must get a filter that has at least 60-gallons per hour.


Most of the time beginner aquarium mistakes are made just because of lack of information and lack of experience. But the thing is that you can learn from your own mistake. Hopefully, by reading through these beginner aquarium mistakes, you can avoid making them yourself in the first place. If you understand these mistakes, you will be off to a great start being one of the greatest aquarists in the hobby.