What size fish tank should I get?

Before buying your first aquarium you should think about several important issues, namely:

• The size of the tank (its capacity in gallons/liters)
• The shape of the tank
• Space for the aquarium
• Money aspect

You know, there is no one-size-fits-all. Let us proceed step by step to explain the most important aspects related to your new hobby. 

The size of the tank

One of the most important factors to consider when buying a fish tank is the size of the tank.

The best fish tank size for different common freshwater fish depends on many factors.

If you have a large living space, a large tank will give you more options for decorating. A large tank also allows for a greater variety of freshwater fish species. A small tank may be better suited for those who have a limited space.  A tank of about 10 gallons is a good sized tank for a small house or apartment.

It is best to measure the space you have available before you buy a fish tank. There are many types of aquariums available. Some are more expensive than others.

Here you must ask yourself: Which fish do you want to keep in your fish tank? Are they to be small like dwarf shrimps, or perhaps small fish species or large fish species?

It is best to go to a pet store or stores and see what we have to choose from. Once you have found something for you, it is best to check a few important points:

• water requirements (pH level, temperature and water hardness)
• disposition and behavior during spawning
• maximum size of a given species

Once we have done this, we can verify our choice to a few species that will best fit together in all respects. Knowing what and how many freshwater fish we will have, we can move on to choosing the tank capacity. 

Bigger fish tanks are better

It seems that the larger fish tank, the better for you and for your charges. Why do we make such assumptions?

Well, in larger tanks (from about 20 gallon) the aquatic environment naturally defends itself better against unwanted changes that may occur in it.

In short: the fish have more space for themselves and we spend less time checking the condition of the tank, water and plants.

Buying a large tank seems to be a very good solution. Although a smaller aquarium may seem to be a more economical option, in case of a desire to change the tank into a bigger one it generates additional costs (for example we need to buy a larger filter). 

I know from experience that beginner aquarists often quite quickly want to change the aquarium for a larger one.

After all, someone may say that at the beginning you can buy a small fish tank, and when our new passion develops, you can change it to a larger one. A smaller aquarium can then be used, for example, as a quarantine tank for newly purchased animals and plants.

Of course, this is only a good solution if we find a place for two tanks and we really look to breeding the freshwater fish in the future.

Larger aquarium means more freedom in choosing the fish, plants or interior arrangement. Of course you have to reckon with higher costs of its setup (equipment, substrate, plants etc.).

In that case, your best option is to buy the largest fish tank you can afford and find the right space for. If your aquarium is too small, then you should choose another kind of fish to keep in it.  Generally speaking, the bigger the aquarium the happier your fish will be.

Tank capacity

Let’s move on to the tank capacity:

• Fish tanks up to 10 gallons – are more suitable for nano aquariums where we keep small fish species; we should remember that the minimum aquarium capacity for one fish is 5 gallons . Small aquariums are very susceptible to pH fluctuations and accumulation of harmful substances. For many fish this is insufficient area to swim; these aquariums can be ideal for growing algae or plants; we must regularly monitor the pH and remember to have good filtration.
• Fish tanks 10 – 40 gallons – seem to be an ideal choice for aquarium beginners, who want to keep common fish species. They don’t take up very much space and are perfect as decor for our home. In fish tanks under 20 gallons we can accommodate a handful of smaller fish. These tanks will still require proper fish tanks above 20 gallons are most optimal. Of course we will pay more for these large but the size will be ideal for a dozen small fish. It is also easier to maintain the biological balance in these aquariums.  
• Over 40 gallons – are recommended for people more experienced in fishkeeping. These fish tanks are optimal for a wide variety of fish. Large tanks are very spectacular. Maintaining the biological balance in large aquariums is definitely easier than in smaller tanks. However, keeping clean in large tanks can be hard work. The weight of the aquarium is very important. Large tanks need an aquarium stand. When choosing a place for a very large aquarium, we must consider its weight. Remember to consider all risk factors.

Aquarium sizes for 10 most common freshwater fish species

Here are some of the most popular freshwater fish for pets and the best aquarium sizes for them. You can have many great and popular fish species as pets, from tropical fish to freshwater fish.

This may sound strange, however I am addressing all future breeders:

DO NOT BUY AN AQUARIUM BOWL – NOTHING GOOD WILL COME OUT OF IT!

In a ball, a fish feels like in a prison. Why?

• No place to swim,
• No place to hide,
• Lack of enough oxygen to breathe, mainly due to lack of filter and very little water
• Lack of oxygen causes poisoning with dangerous nitrogen compounds due to the lack of proper decomposition of organic matter (mainly faeces and food residues),
• Lack of a heater causes the lack of a constant water temperature, which may lead to a slow death of your fish
• Lack of constant lighting – the lamp on the desk can only worsen the situation (water heats up in an uncontrolled way, which means that it begins to lack oxygen),
• Biological imbalance – due to the size of the aquarium bowl it is practically impossible

Many people think of goldfish in small fish bowls when they think of pet fish. Aquarium bowl isn’t a good home for goldfish. Goldfish need very large tanks, at least 10 gallons per fish.

Tank dimensions

When choosing a fish tank, we should be guided by what dimensions would be the most appropriate for us. When it comes to height and width of the fish tank, these dimensions should be the same, or they may differ from each other by no more than 10 cm.

This will make it easier to arrange the bottom of the tank so that it looks good. High tanks are troublesome for maintenance and do not present themselves so well.

Another important aspect when looking for the right aquarium is the difference between the length of the tank and its height. With the height of the aquarium, the penetration of light into the substrate and plants deteriorates.

The oxygenation of all the water also changes, which affects the fish. In addition, with a higher aquarium, the fish will have less space to swim. This is important because the fish move horizontally, not vertically.

Types of glass

The appearance of a fish tank depends on many parameters. In addition to the previously mentioned parameters of the length, height and shape of the tank, the type of glass it is made of is also important – its grinding and gluing.

We currently use two types of glass for the production of aquariums:

• Float glass
• Optiwhite glass

Float glass

Float glass is the most commonly used type of glass. Its name comes from the method of production, which in short consists in drawing out a long layer of glass and obtaining the appropriate thickness thanks to the action of molten tin spilled on the glass and gravitational force. This method was invented by Sir Alastair Pilkington in 1952. Glass produced in this way has several characteristic features:

• it is almost perfectly flat and smooth
• no distortion
• has no optical defects
• it reaches a thickness of 0.1 to 25 mm

Float glass, in contrast to the second option, is less transparent at the edges due to the presence of iron oxides. In this case, the thicker the layer of glass, the more visible the green color on the edges.

Optiwhite glass

Another option is optiwhite glass. Due to its parameters it is also used in interior design. Its main features are:

• very high transparency due to reduced content of iron oxides
• very high light and solar energy transmittance coefficient
• thickness of 2 to 19 mm

As optiwhite glass is transparent, it better reflects the natural colors of plants and freshwater fish. It is produced by most manufacturers and may have different names: Optiwhite, Diamant, Ultra Clear, etc.

Which type of glass we should choose? From the point of view of a beginner aquarist, the optiwhite glass option seems interesting. The price here is much higher than that of float glass.

Transparency, the aquarium made of optiwhite glass is more targeted at people who plan to set up a natural aquarium or want to compete in exhibition competitions.

Due to its transparency, the optiwhite glass fish tank is more aimed at people who plan to set up a natural aquarium or want to compete in exhibition competitions.

Aquarium bonding

There are two methods of gluing glass together with silicone:

• Butt bonding
• Bead bonding

Butt bonding

The first type consists in setting all the panes forming the tank walls on the pane forming the bottom. The longer panes (front and rear) are placed on the outside, and the shorter panes (side) between the longer ones. You can also glue the longer panes between the side ones, which reduces stress and improves the entire aquarium structure.  The stability of this silicone seam is much higher.

Bead bonding

In bead bonding the panes are glued from the outside in such a way that their edges form a right angle (90º) and are 1 mm apart. The space created in this way is filled with silicone. The bottom panes are glued between the side panes. This method requires significantly more silicone.

How to recognize that your fish tank has been glued incorrectly?

This can be assessed on the basis of several important observations:

– bad fitting of glass panes – partially or completely (along the entire length) protruding edges in one or all corners. The panes of glass cannot be shifted against each other. This type of defect may result in additional stresses that will cause the glass to break

– glue deficiencies – noticeable with cavities or air bubbles in the joint after flooding the aquarium with water. A defect of this type may cause our tank to become unsealed

– excess silicone – visible silicone rollers inside the corners, as well as the protruding layer of silicone beyond the edges of the fish tank (the adhesive layer should be max 0.5 mm thick)

– no reinforcement bars in aquariums – this applies to tanks with a capacity of more than 40 gallon (150 liters) or a length of more than 100 cm. This type of defect may distort the panes, which may lead to glass breakage.

Tank shapes

There are many different shapes and sizes of aquarium tanks. This is a list of the most popular ones:

– rectangular and square tanks – The most popular tank style in the world is this one. The stands are easy to find and the tanks are easy to fit on any surface that can handle the weight. It is possible to make cleaning a breeze by using your standard cleaning magnet.

– bow tanks – Bow tanks are a popular type of tank. They get their name from the curve in the front of the tank that makes them look like a bow, and they can be placed on any surface large enough to hold the tank. Magnet cleaning can be a lot more difficult than you think. You need to keep certain angles when cleaning the bow.

– wave tanks – wave tanks have become increasingly popular and get their name from the shape of the front of the tank. Wave tanks are typically mounted onto a stand that fits them onto the surface. They can be hung wherever there’s an open surface large enough to hold the entire tank. The odd shape of the wave tank could cause some visual distortions within the tank.

– other – many styles of fish tanks come in different sizes and shapes, some which have pros and cons.

It’s important to remember that the shape of a tank can affect how you decorate it. For example, a round tank may not go well with straight edged rocks.

For some tanks, the height is more important than the shape. It’s not about the height, but the surface area. It doesn’t matter if the tank is high or low, as long as there is enough surface area.  You should be thinking about how you are going to set up the tank first, and then buy the decorations based on that.

One more reason is territory. Some fish are territorial and want to establish their own areas in the tank. To prevent stress, ensure that fish tank is large enough to allow your fish to swim freely.

For this reason, rectangular shaped tanks are the best choice for tropical fish. Some fish prefer a vertical tank, while most fish prefer a taller tank versus a smaller tank.

To conclude, it’s best to find a compromise between your personal taste and the needs of the freshwater fish. When choosing a fish tank, it is important to think about what you want to do with the tank.

Do you plan on keeping the fish? Do you plan on adding plants? Will the tank be used for decoration? How much light will you need? What size will the tank be? What kind of fish are you looking at? Are you going to have a heater? What kind of filter will you use?

Weight of your fish tank

When it comes to the weight of your tank, the weight of the water will likely be the heaviest. A gallon of water weights 8.34 lbs. You need to measure the inside of your tank to calculate how much water is required.

If you have a rectangular-shaped aquarium, you can calculate the volume using the formula: length x width x height. If you have a tank that is not rectangular, you will need another formula.

You don’t need to fill the fish tank completely to the top. You should measure the height of your water line. This calculation will give you the volume of your tank in cubic inches. You can then multiply this number by .004329 to get the number of gallons your tank will hold.

You need to take the number of gallons and multiply it by the weight of water (8.34 lbs/gallon). Now you know the number of pounds of water you should use in your fish tank.

You’ll have to find out how heavy your glass of fish tank is. The manufacturer will give you  information on the weight of the glass so you can factor it into your calculations. Aquarium owners usually add a little weight to the base of their aquariums by filling them with rocks or sand.

The weight of the sand can be calculated by measuring the inside of the tank, and how much space the sand will fill. If you have the total volume in cubic inches, then you can multiply this by 0.055 lbs to find the total weight.

It is important to consider the weight of the fish tank stand. It could cause problems in your home if the furniture and aquarium combine weighs more than it should.

Weigh all the larger pieces of aquarium furniture before they are installed. If necessary, contact a professional to help you with the weight of the equipment.

When measuring all your weights, don’t double count. When determining the weight of the water, it’s important to measure from the inside of the tank and not the outside. If you include the size of the glass when you measure it, you will be adding to the weight of the glass.

If you do the outside, you’re measuring the width of the glass. To get the most precise measurements, be sure to measure accurately.

It is important to make sure that the weight is not overlooked when you setting up a new fish tank. You want to make sure that your furniture supports the tank properly, and that the floors underneath are strong enough to hold it up. By coordinating with your custom aquarium supplier, you’ll be able to create a fish tank that you’ll love.

In conclusion

I’ve been keeping freshwater fish for over 15 years now. In all that time, I’ve learned many valuable lessons, from how to properly setup a fish tank to how to maintain it properly.

I’m sure that by reading this post, you’ll have a better understanding of what size fish tank should you get.

Have you already got a fish tank? What size fish tank do you have? How large was your first tank? If you have size your fish tank should be and which type of fish tank you should buy leave a comment below. I may answer any questions or concerns you might have.