5 Beginner mistakes when starting an aquarium

Setting up your first aquarium is a great new experience. However for a beginner, trying to maintain an aquarium can be challenging. They can make many mistakes. And most of the time, these beginner aquarium mistakes are caused due to a lack of information and experience. There are numerous sources of information available online, but you may not always find the correct information and the right solution for your real-life situation. This article will help you resolve the most common mistakes you can make while setting up an aquarium and also help you to avoid them. Avoiding these initial errors is much easier than trying to correct them at a later date. So, let's take a look at 5 of the most common beginner aquarium mistakes and how you can avoid them.

1. Adding fish before the aquarium is ready

This is one of the most common problems for beginners. From vibrant goldfish to beautiful underwater decor, we know the excitement that comes with a new aquarium. You may be keen to add your selected fish to their new home as soon as you've set up your tank. And we don't blame you! There is nothing as pleasing as watching your beautiful fish swim and live in an aquarium you just made for them. However, if you add a group of fish to your aquarium without first setting the correct water parameters and acclimatizing them, your little creatures will likely die. When it comes to tanks, beginning aquarists often misjudge the importance of the different chemical levels and nitrogen cycle. Your tank needs to stabilize before your little swimmers are added. This includes running your aquarium on a nitrogen cycle and the proper water levels (hardness, pH, temperature). Once you have finished this process, only then can you add fish to your tank.

2. Buying a tiny/small aquarium

A common myth among beginner aquarists is that a smaller tank is easier to maintain than a larger one. Larger tanks are more expensive, and might require a more complex setup process. This may be true to some extent, but larger tanks come in handy. Due to smaller quantity in water, any change in a small tank can quickly alter the overall condition, causing the fish to become ill rapidly without much warning. Larger tanks are easy to monitor when sudden changes occur. For beginners, we recommend purchasing a tank between 40 and 60 gallons in size. This might seem large but you will thank us in the long run! Many hobbyists also don't realize the space requirements of many fish, for example the minimum recommended tank size for just 2 goldfish is 20 gallons!

3. Adding too many fish to a tank

Imagine being trapped in a box with a group of people, unable to move. That is almost exactly what happens when you have too many fish in a tank. And, unfortunately, it is a mistake that many beginners make with their new aquariums. Too many fish can cause problems with your tank's filtration system due to increased ammonia production. This can make maintaining your aquarium water quality an absolute nightmare. Your tank can also have reduced oxygen levels, making it difficult for your fish to breathe in their crowded home. Other problems with having too many fish include possible aggression between the fish, more algae, and high nitrate levels (causing the fish to get sick). So, the general rule of thumb: If you wouldn't live in a house full of people, your fish shouldn't either. The basic rules of thumb is that for every inch of fish you need 4 litres of water. (this is obviously very basic and differs a lot but you should at least keep it in your mind while stocking your tank).

4. Mixing incompatible fish

It's easy to think that all fish get along. After all, not many species of fish seem aggressive or territorial. This is where many beginning aquarists go wrong. While docile and calm, many fish species are territorial when it comes to certain areas of their tanks. They can bite and attack other fish that come close to their declared "places." Aggressive fish, such as the extremely common Siamese fighting fish (also known as bettas), are naturally aggressive and generally stay away from other fish (even their own species) to avoid potential losses. When choosing fish for your tank, it is essential to ensure that all species are compatible with each other. High compatibility with fish is one of the best ways to ensure that your aquarium is thriving and prosperous.

5. Replacing all of the aquarium water

When it comes time to clean, many beginners think it is good idea to remove all of the water from their aquarium. This is a big no no and is sure to kill your fish. Removing the water from your tank kills the healthy bacteria your fish needs to live and destroys its nitrogen cycle. Water changes should be a slow and careful process to ensure that the water parameters do not become drastically unbalanced. In general, you should remove 15-25% of the water from your tank and nothing else. This amount helps you maintain a healthy pH, temperature, and nitrate balance, preventing fish from getting sick. Be sure to treat the new water and test its chemical levels (especially ammonia levels) before adding it to the aquarium. You can do this by using a water test kit.

Additional tip: make sure to use tank water to clean your aquarium filter. As has been mentioned already tap water will kill the good bacteria in your fish tank. A good method is to do a water change and then wash your filter in the bucket of water you just removed from the aquarium.


I know it can seem daunting with so many opinions out there on the internet, the best thing to do is simply get started and try things out. You'll quickly learn what works for you and over time your knowledge will improve.