Can a Fish Tank Be Too Big?

Can a Fish Tank Be Too

It is a common problem that once you start looking into setting up a fish tank, that the size of the tank you want gets bigger and bigger and bigger. There are just so many exciting and unique fish and features to add! And with so many impressive décor pieces that you’ll quickly find yourself looking larger tanks.

But can a fish tank be too big? There is no such thing as too big when it comes to fish tanks as long as the location where you are placing the tank can withstand the weight of the fish tank. Large tanks are good for your fish, but for fish that like small spaces, you can add caves and plants to give them places to hide.

So there is really no reason not to have a large tank! In this article, we will go over everything you need to know about large tanks and tank size so that you can make the best decision when setting up your next aquarium.

A Word About Tank Size

Fish tanks are generally differentiated by how much water they hold in gallons and sometimes by their shape. Most fish tanks are rectangular or hexagonal, but custom tanks can be made in a variety of shapes.

It is important to note that two tanks may be listed as the same gallon size, but can have very different dimensions.

Fish Tank Size Weight of Empty Tank Weight of Fresh Water Weight of Salt Water
5 gallon 15 lbs 42 lbs 43 lbs
19 litres 6.8 kg 19 kg 19.5 kg
10 gallon 35 lbs 83 lbs 86 lbs
38 litres 15.9 kg 37.6 kg 39 kg
20 gallon 60 lbs 167 lbs 172 lbs
76 litres 27 kg 75.8 kg 78 kg
55 gallon 120 lbs 459 lbs 473 lbs
208 litres 54.4 kg 208 kg 215 kg
75 gallon 150 lbs 625 lbs 645 lbs
284 litres 68 kg 284 kg 293 kg
100 gallon 200 lbs 834 lbs 860 lbs
379 litres 91 kg 378 kg 390 kg
300 gallon 450 lbs 2502 lbs 2580 lbs
1135 litres 204 kg 1135 kg 1170 kg

These numbers are just estimates. The weight of your entire tank set up will vary depending on the following: 

  • The materials used (glass is heavier than acrylic)
  • The thickness of materials used
  • Whether the listed gallons is the actual capacity of the tank
  • The décor and substrate used
  • The additional equipment attached to the tank
  • The weight of the tank’s base

You can see that it isn’t such a stretch for a 100-gallon tank to weigh close to 1000 – 1,500 pounds! To estimate how much your tank will weigh, refer to the specs listed by the manufacturer.

Here’s What You Need to Know Before Buying a Large Fish Tank

If you’ve decided that you want to have a large fish tank in your home, you’re not alone. Large fish tanks are absolutely stunning, and they can add interest to any room. There are some things you should consider before making your big purchase, however.

Let’s dig into some of the things you should consider before buying a large fish tank.

Safety Considerations for Larger Tanks

Before anything else, you have to make sure that your floor can handle the weight of a large fish tank. If you’re just looking at a 55-gallon tank (which is still quite large), this probably won’t be an issue, but as you get up into the 100 gallon or larger tanks, it is a real consideration.

Fish tanks are heavy. The average 100-gallon tank can weigh around (and more than in some cases) 850 pounds when it is filled with water. Add in 100 pounds of a substrate and a heavy-duty stand to put the tank on, and you’re easily looking at one of the heaviest items in your home.

If you have any reservations about the supports under your floor or live in an older home, you should speak with a reputable general contractor about adding support under your fish tank so that it doesn’t damage your home.

A Larger Fish Tank Will be More Expensive

It goes without saying that purchasing a larger tank will be more expensive than buying a smaller tank, but there are other expenses you should consider as well, including the cost of:

  • Substrate
  • Filters
  • Air pump
  • Heaters
  • Plants and décor
  • Lights
  • Water costs
  • Electricity

Most of these are one time costs, and most would consider the extra electricity required to run your tank equipment negligible, but they are costs you should take into account.  

Will a Larger Fish Tank Require More Maintenance?

Yes and no. The larger a fish tank is, the more stable the conditions of the water will be. This means you may not need to treat the water of the tank as often as in a smaller tank.

But routine maintenance tasks will be on a larger scale. Consider these tasks:

  • When you have to do partial water changes, you’re going to be emptying A LOT more water and replenishing with a lot more water.
  • You will also have significantly more substrate to clean.
  • You may have more filters to change out and equipment to maintain, but filters may not need changing as often as in smaller tanks.

Other than that, you can expect very similar maintenance needs no matter the size of your tank.

More Equipment Can Mean More Noise

The filters and air pumps in fish tanks can make considerable noise, and since your larger fish tank will require more equipment, it may be noisier.

If this is something that will bother you, be sure to purchase equipment that is known to be quieter such as:

  • Use internal filters or under gravel filters with an internal powerhead
  • Skip the air pump (not always necessary in a well-filtered tank)

The noise of a larger fish tank won’t bother everyone. Some actually find the trickle of water from the filter and the hum of the equipment to be soothing.

Large Tanks Can Leak

So any fish tank can spring a leak, whether from a manufacturer’s defect or damage incurred at home, but if a large tank begins to leak, it has the potential to leak a whole lot of water.

As a point of comparison, consider that many people will have drains in their laundry room in case of a washing machine disaster, but the typical washing machine only holds about 30 gallons of water. Most people don’t think about preparing for a fish tank disaster.

You Can Still Overcrowd a Large Tank

No matter how large your tank is, you can still overcrowd it. It is always better to give your fish plenty of room to swim and create their fishy homes.

Overcrowded fish will become aggressive with each other and be unhappy and stressed. This can lead to needless fish death. Overcrowding will also put a strain on your fish tank equipment and the water conditions of the tank. 

No Need For Upgrading Your Whole Tank Set-Up

If you know that you are going to want more and more fish, then starting out with a large tank will save you money in the long run because you won’t need to upgrade your tank size several times.

This will also save your fish a lot of stress as changing tanks can be hard on them.

If you love fish and fish tanks, then it is really no question. The bigger, the better! The downsides of a large aquarium are not so great that they cannot be overcome by someone with proper motivation!

Can a Fish Tank Be Too Deep?

Depending on the type of fish you have in your tank, a fish tank can be too deep. Some fish, like bettas, prefer shallow waters, and they may have trouble reaching the top of a very deep fish tank. 

If bettas cannot reach the top of the tank, it can be problematic because they may never swim to the top of the tank for food, or they may just get tired out or stressed in the process. Tank depth is usually not a problem in rectangular tanks, but hexagon-shaped tanks tend to be very deep.

You can help mitigate this issue by providing floating plants for the fish to hide in on their trip to the top. Deep tanks also tend to be narrower, this isn’t ideal for most fish, especially large fish, but we will discuss this more on this later.

Form a comfort standpoint, I would love to see you reaching into the deep tank with your hand during cleaning. Save your self a headache and pls get a reasonable deep/high fish tank.

How Big of a Fish Tank Do I Need?

How Big of a Fish Tank Do I Need by
Picture: How Big of a Fish Tank Do I Need?

How big of a fish tank you need depends on how many fish you want to keep and the variety of fish you want to keep. Let’s go over some of these factors.

How Many Fish You Want to Keep

If you want to have several different kinds of fish, all living harmoniously together, you’re going to need a large tank.

Overcrowding leads to:

  • Low oxygen levels
  • Too much ammonia and nitrate in the water
  • Dirty tank
  • Aggressive fish behavior
  • Fish that don’t grow to full size

It is always better to have a tank that is larger than your fish need than one that is smaller than your fish need.

Many people recommend following the 1 inch of fish per gallon rule. Meaning if you have fish that are 1 inch long, you could have 55 of them in a 55-gallon tank. This rule has its flaws and should only be used for small fish.

Another rule of thumb is 10 gallons per fish, but this might be excessive for smaller, schooling breeds.It is always best to avoid these rules of thumb. Instead, look at the recommendations for each breed you want to add to your tank and make an educated decision for your tank size based on them.

How Big Are the Fish?

Larger fish need more space! It is as simple as that. Oscars, for example, require at least 30 gallons per fish! Some recommend as much as 100 gallons for a pair! Oscars can reach 18 inches in length when they reach adulthood, so the tank requirements are understandable. 

Neon tetras, on the other side of the spectrum, only grow to be around an inch, so you could comfortably fit about 75 of them in a 100-gallon fish tank!The size of the fish you’d like to keep will directly impact tank size. Before committing to specific tank size, research your fish!

Is Fish Tank Length Important?

Absolutely. The reason that fish tanks tend to be rectangular in shape is that fish like to swim back and forth and not just straight up and down. It also increases the surface area of the water, which makes it easier for oxygen to enter the water.

Larger fish will need longer tanks and wider so that they can swim laterally.

Those tall hexagon shaped tanks might be aesthetically pleasing to some, but they do not offer a lot of surface area, for larger fish, they may not offer enough opportunity for swimming laterally.

Do You Want Your Fish Tank to be a Center Piece in Your Home or Business?

If you want your fish tank to be a talking piece or provide entertainment to waiting patrons, the bigger the tank is, the better off you’ll be.

Large tanks with a variety of fish breeds will give visitors to your home or business plenty to look at and talk about. A smaller tank may be ignored, or it may even seem out of place.

Will Fish Get Bored in a Small Tank?

Whether fish have the mental capacity to get bored is out for debate, but any fish placed in a tank that is too small for it or in conditions that are unnatural for it will undoubtedly get stressed and fail to thrive.

For example, schooling fish should really have companions to school with to satisfy their natural instincts. Fish that like to have hiding spots should have access to places to hide so that they feel safe and secure. Once again, knowing and researching the fish you’d like to keep is essential!

Do You Need a Large Tank if You Want a Planted Tank?

Planted tanks require careful planning to set up, but you will find that ongoing maintenance requirements are less. If you have a large tank, reduced maintenance can be nice, but you don’t need a large tank to have a planted tank, and small tanks can benefit from the reduced maintenance just as much as large tanks.

Does the Size of a Fish Tank Determine How Large a Fish Will Grow?

Sort of, yes. A fish will not grow to the size it is genetically meant to grow in a small tank. To put it simply, small tanks stunt growth. So it isn’t so much that a large tank will make a fish grow larger as a large tank allows the fish to reach its natural size, and a small tank does not.

According to It’s Not Just a Fish, an organization that promotes good practices in fishkeeping, here are some of the reasons small tanks cause stunted growth:

  • Does not allow the fish proper exercise
  • Stresses your fish out, which causes the release of cortisol
  • Does not allow growth stunting hormones and pheromones to be diluted
  • Water in small tanks may have too much ammonia, nitrate, and nitrite

Stunting the growth of your fish is just one more reason to have a larger tank, at least when you’re keeping fish that are on the larger side.  

Can You Put a Betta in a Big Tank?

The myth around bettas is that they prefer to live in small tanks, but that isn’t really the case. Although you will often seem them housed in tiny bowls at the fish store, bettas would benefit from a 5-gallon tank, giving it room to swim around and keeping the quality of the water stable. 

Bettas can do perfectly well in larger tanks as long as they are given places to hide, and the tank is unreasonably deep. To keep your betta happy in a large tank, provide lots of plants and some sort of hiding cave-like spot. The tank size won’t matter to them!

Do Goldfish Need Big Tanks?

This depends on what you mean by goldfish. Goldfish are actually a type of carp that has been domesticated, and they can grow to be rather large, sometimes over a foot long.

One fisherman in China even caught one in the wild that weighed 3 pounds, according to National Geographic. You would easily need over a 100-gallon tank for this magnificent fish!

Depending on the specific type of goldfish you select, you may need a larger tank. Common goldish tend to grow larger (10 inches and larger), while fancy goldfish tend to remain smaller (around 4 inches).

Too Big? Never!

A fish tank can only be too big if you aren’t up to the challenge of caring for it or your floor simply can’t handle the weight, and it is never a problem for the fish! Even those who like tight spots can find a good place with the right accouterments inside!

So if you have big tank dreams, go for it! Invest in a big tank and fill with a variety of fish for a stunning and entertaining centerpiece in your home.

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