100 Gallon Fish Tank: Our Top 3 Choices

Time for an upgrade? A 100-gallon (378.5 L) tank might be in your future.

However, 100-gallon fish tanks are not very common to come across and your local pet store might not carry the option that is absolutely best for you. Whether you’re wanting to set up a freshwater or saltwater tank, a larger aquarium is a big investment and you need to make sure that you get it right from the start!

In this article, we’ll discuss some of the benefits of having a larger tank, as well as our top 3 choices for 100-gallon fish tanks!

Benefits of a larger tank

While nano aquariums might seem like they’re less maintenance than larger tanks, this is not true. There are a few reasons why bigger is almost always better in the aquarium hobby:

More space. Simply put, a larger aquarium means more space! You might be thinking that most importantly, this allows for more fish; but even more important than that, more space allows for more surface area for beneficial bacteria to grow.

A larger aquarium not only provides more surface area on the sides of the walls, but there is also more space for decorations that bacteria can grow on. Aquarium equipment, like filtration, powerheads, heaters, and protein skimmers will also add to the amount of space for bacteria to establish itself. The more bacteria there are, the more that your system will be able to regulate its own parameters and contained the ecosystem.

More livestock. Of course, a larger aquarium will allow for more livestock, like fish, corals, plants, and invertebrates. A more expansive floorplan will allow for active fish to swim while additional tank height will let individual fish inhabit their preferred portion of the water column.

More space in general also means more space for fish to set up territories. One of the main problems with small tanks is that most times the hobbyist wants a lot of fish, but also needs to consider that each fish needs its own area within the tank; mapping out aggression can get pretty difficult, especially in a saltwater system! While aggression still needs to be monitored, larger systems can help dilute any immediate problems that would otherwise be felt in a smaller tank.

Self-sustaining. Lastly, a larger aquarium does a better job of imitating a natural environment. Not only can more bacteria grow and more species be displayed, but the tank will also take on a life of its own and go on auto-pilot at some points.

In the case of a power outage, larger tanks take longer to cool off and can make the difference between losing everything in your tank to only losing a few things here and there. Larger tanks also don’t experience as drastic changes in water parameters as smaller tanks do; since there is a greater water volume, influxes of ammonia or phosphate are more evenly integrated into the system and have a smaller effect on the whole ecosystem.

Our top 3 100-gallon fish tank choices

We have compiled a list of our top 3 choices for 100-gallon fish tank systems. We have based our decisions on price, quality, customer reviews, and what is included with the tank.

INT 100 Gallon Aquarium w/ APS Stand

INT Tank
Innovative Marine

The INT 100 Gallon Aquarium w/ APS Stand is one of the most popular 100-gallon fish tank setups available. These tanks measure 47.3 L x 23.6 W x 19.7 H inches (120.1 L x 59.9 W x 50.0 H cm) and are made from Ultra-Thick 15mm High Clarity Low Iron Glass sealed with black silicone. The pre-drilled glass tank includes an internal Trapezoid Infinity Overflow with dual return nozzles, Pro Series screen lid, pre-installed rubber mat, and the required plumbing.

The aluminum, corrosion-resistant stand measures 47.5 L x 23.5 W x 35.8 H (120.7 L x 59.7 W x 90.9 H cm). The stand is available in matte black and has plenty of room for a sizeable sump; however, an actual sump is not included.

If you need help picking out a sump, make sure to check out our most top-rated aquarium sumps for your tank here!

What we like:

  • Seamless open-top design with an included screen covering
  • Longer tank than taller tank
  • Solid black background

Room for improvement:

  • Sump and other equipment not included
  • Short tank height

Waterbox Aquariums Reef 100.3

Waterbox Tank
Waterbox Aquariums

The Waterbox Aquariums Reef 100.3 is an all-in-one system for setting up the reef aquarium of your dreams. These tanks measure 35.4 L × 23.6 W × 21.7 H inches (89.9 L x 59.9 W x 55.11 H cm) and are cut from Starphire Ultra-Clear glass for great clarity and viewing. They feature an internal, solid glass overflow box with two adjustable return nozzles.

The Reef 100.3 also includes an impressive sump, with four main chambers. The first chamber is set up into two small sections, with two slots to install a mesh and micron filter sock respectively. The second chamber provides more than enough room for a protein skimmer and/or refugium. The third chamber is further used for sponge filtration and de-bubbling and sent to the return pump. The last chamber is saved as an auto top-off (ATO) reserve for freshwater. All plumbing is included, preassembled, and glue-free; a safety drain is also included for extra security.

A soft-close stand comes with the aquarium and can be customized to be black or white with a black interior and measures 35.4 L × 23.7 W × 35.4 H inches (89.9 L x 60.2 W x 89.9 H cm). Lighting systems can be purchased for an additional cost. This tank can also be used for freshwater purposes, but it is largely advertised for saltwater systems.

What we like:

  • All-in-one and reef ready
  • Starphire Ultra Clear glass for clear viewing
  • Pre-drilled tank and pre-assembled plumbing
  • Sump designed for efficiency with silencing in mind

Room for improvement:

  • Does not include return pump, protein skimmer, or auto top-off mechanics
  • Auto top-off reserve is a little small
  • Problems with quality control during shipping
  • Expensive

Clear-For-Life 100-Gallon Rectangle UniQuarium

PetSmart Tank

If you’re under a tight budget but still want an all-in-one system, then the Clear-For-Life 100 Gallon Rectangle UniQuarium could be great for you. These aquariums measure 60 L x 18 W x 20 H inches (125.4 L x 45.7 W x 50.8 H cm) and are made from thick acrylic designed for increasing support and clarity more than glass. The corners are rounded for a seamless effect that transfers into the cut-out lid.

This 100-gallon aquarium is different from the rest in that it is not drilled for external filtration, instead, all of the needed filter chambers are hidden behind a blue or sapphire blue background. There are three main chambers with the first containing sponge filters, the second filled with bio-balls, and the third used for housing the return pump; many hobbyists have dedicated some of the second chambers for a protein skimmer and/or other media. An aquarium stand is not included.

What we like:

  • Affordable acrylic tank; can be found in stores
  • Built-in filtration that can still be customized
  • Very long tank

Room for improvement:

  • Limited filtration space; areas can be difficult to reach/clean
  • The lid cannot be removed
  • No stand included


Here are some questions you should ask yourself before you go out and buy your aquarium!

How much does a 100-gallon tank cost?

A 100-gallon fish tank tends to be more expensive than other regularly-sized aquariums. A brand new system will easily cost close to or over $1,000. Luckily, many of the listed systems include filtration and various accessories that would be an additional cost otherwise.

However, it is important to keep in mind that substrate, decorations, and other various equipment and media will easily cost another several hundred dollars as well if purchased brand new.

What are the dimensions of a 100-gallon fish tank?

A 100 gallon tank is not a typical aquarium size; you may have to go to a special aquarium shop and/or online to find an aquarium that is labeled as exactly 100 gallons.

In general, a 100-gallon tank will measure between 48-60 inches (121.9-152.4 cm) long, 21 inches (53.3 cm) wide, and 20 inches (50.8 cm) high. Dimensions are important to consider given the area that the tank will be in as well as what kind of system you want; active schooling fish will prefer longer tanks, while taller fish, like angelfish, will need more headspace.

How many fish can you put in a 100-gallon tank?

How many fish you can keep in your 100-gallon fish tank depends entirely on the setup of the system. Freshwater aquariums allow for more fish in general, as the species tend to be smaller and less aggressive. However, most freshwater species do better in schools and will need to be considered in terms of quantity. Freshwater predatory species are best kept in small numbers, due to their potential sizes and aggression.

Saltwater stocking is entirely based on the selection of fish you decide on. ‘Community’ saltwater species still need more space than most freshwater species due to heightened aggression. More predatory species will also need to be kept with like-species and should only be kept with a select few.

In general, freshwater community aquariums will allow for the most fish. Also, consider setting up a planted tank or a reef tank if you don’t want to have just fish in your tank!


Whether you’re upgrading or starting a new tank entirely, a 100-gallon aquarium is a great choice for both freshwater and saltwater purposes. Though it is not a size seen too often, most online companies offer all-in-one setups that leave little to purchase otherwise. Make sure that you research each tank and try to plan your setup beforehand so that your dream aquarium can materialize!

If you have any questions about 100-gallon fish tank systems or have an aquarium of this size of your own, don’t hesitate to leave a comment below!


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