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One of the first things you’ll be told when starting an aquarium is: bigger is better. But how big is big enough?

After 75 gallons (283.9 L), the next most common aquarium size is usually 125 gallons (473.2 L). A 50 gallon (189.3 L) difference between the two might not seem like a lot, but that extra space opens up a ton of new possibilities for aquascaping and stocking. While it’s true that larger tanks require more powerful equipment which is more expensive, parameters are easier to control so that there is more time to enjoy the natural ecosystem that takes place in your tank!

Keep reading to find out if a 125-gallon aquarium is right for you and which options fit your aquarium needs!

Our top 125-gallon aquarium choices

It can be difficult comparing aquarium systems as most tend to look the same, but all have slightly different dimensions and included accessories. We have compiled a list of our top 125 gallon aquariums based on price, customer rating, quality, and included accessories to make choosing one easier for you.

Aqueon® LED Aquarium & Stand Ensemble, 125 Gallon

The Aqueon® LED Aquarium & Stand Ensemble, 125 Gallon is one of the most inclusive and best quality aquarium kits for its price. These glass aquariums measure 72.5″ L x 18.5″ W x 23.4″ H (184.2 L x 47.0 W x 59.4 H cm) and include a matching black and grey stand that measures 74.0″ L x 21.0″ W x 30.6″ H (188.0 L x 53.3 W x 77.7 H cm). This ensemble also includes two LED strip lights that can independently be turned on and off with a simple switch as well as multiple glass panels that act as a hood to lessen evaporation and stop fish from jumping.

For its price, the Aqueon® LED Aquarium & Stand Ensemble, 125 Gallon is unbeatable for a standard-sized 125-gallon aquarium. However, the LED lights are only meant for display and will not support plants or corals. Some customer ratings have also commented on the quality and endurance of the stand, but for the price, a different stand can be purchased and still remain in the budget.

What we like:

• Very inexpensive
• Includes glass aquarium, stand, LED lights, and glass covers
• LED light strips can be individually replaced instead of having to replace the whole light fixture
• Standard 125 gallon dimensions

Room for improvement:

• Basic LED lights
• No filtration, heater, or other aquarium equipment included
• Low-quality stand

Marineland 125 Corner-Flo™ Black Rectangular Aquarium

If you’re looking for a fish tank that is already drilled for filtration, then the Marineland 125 Corner-Flo™ Black Rectangular Aquarium might be for you. These glass tanks can either come in the traditional black outlining or can be customized with oak trim, but both will have black silicone. The Marineland 125 measures 72″ L x 18″ W x 22″ H (182.9 L x 45.7 W x 55.9 H cm) and has two pre-installed overflow boxes at the back of each corner with pre-drilled holes for external filtration. Some plumbing accessories are included, like bulkhead fittings, drain and return pipes, and dual Loc-Line® outlet nozzles, though an aquarium hood and stand will need to be purchased separately.

The rating of this tank is about average, as some customers have experienced leaks from poor silicone coverage. Other customers have had complete success with the tank, and find that pre-drilled overflows make external filtration less intimidating.

What we like:

• Pre-drilled glass for external filtration
• Pre-installed overflow panels
• Some plumbing included
• Standard 125 gallon dimensions

Room for improvement:

• Stand and additional equipment not included
• Overflow panels cannot be moved and/or easily replaced
• Potential silicone coverage issues

ELOS System Diamond Line 120 XL (127 gal)

Slightly larger than a traditional 125-gallon aquarium, the rimless System Diamond Line 120 XL (127 gal) is almost as top-of-the-line as you can get. These tanks are made from ELOS Diamond Glass and have polished edges for a clean and seamless look; the tank measures 47.24″ L x 31.50″ W x 19.70″ H (120 L x 80 W x 50 H cm). The square 120xl stand has a water-resistant core and can be customized in color as well as in finish; the stand measures 47.24″ L x 31.50″ W x 35.00″ H (120 L x 80 W x 89 H cm) for an even balance with the dimensions of the tank.

These tanks also include a pre-installed compact QuietDrain overflow which can lead to an optional SumpSS 36 Bashsea External Hybrid filter type. These sumps are designed to fit comfortably in the cabinet and offer a de-gas chamber, mechanical chamber, and chemical chamber. The following plumbing is included: corrugated drain hose, red silicone return hose, PVC fittings, Teflon tape.

What we like:

• High end, top quality, rimless, and polished edges
• 98% clarity glass
• Stand included

Room for improvement:

• Expensive
• Untraditional size and dimensions
• Sump not included

FAQ

How big is a 125 gallon fish tank?

A typical 125 gallon aquarium is equivalent to 473.2 L. The standard dimensions are 72″ L x 18″ W x 21″ H (182.9 L x 45.7 W x 53.3 H cm). These may vary given the shape and design of the individual tank.

How many fish can be in a 125 gallon tank?

How many fish you can get for a 125 gallon aquarium depends entirely on if the system is freshwater or saltwater, predatory or community, as well as on the general aquascape, flow, and biotope of the system.

Freshwater aquariums will usually allow for more fish and will typically require fish to be kept in larger schools than saltwater. Saltwater fish need lots of room to establish territories and most species like to have enough open space for swimming, like angels and tangs.

Predatory fish are best kept in small numbers so that the tank can let them get to their maximum size and to prevent issues with aggression.

How much does a 125 gallon aquarium weigh?

125 gallons of water weighs 1042.5 lbs (472.9 kg) alone. An empty 125 gallon aquarium weighs about 200 pounds (90.7 kg). Now imagine adding the weight of the substrate, rocks, filtration, stand, lighting, and other aquarium equipment; this could easily end up weighing close to, if not more than, 2000 pounds (907.2 kg)!

Will my floor hold a 125 gallon aquarium?

This is definitely an important question to ask yourself regardless of where you plan on putting your aquarium. Every house has a different floorplan, with support beams running different ways; in general, it is best to put a fish tank over as many floorboards as possible to better distribute weight evenly.

Even though a 125 gallon aquarium is long enough to be placed over several floorboards, it may still not be enough. For the best chances of staying worry-free, it is always recommended to keep fish tanks on the ground level. It is even better if the tank can be placed on an area reinforced with concrete.

Conclusion

It can be a little scary to undertake such a large aquarium system, but a 125 gallon aquarium can be transformed into a beautiful Indonesian reef or a slice of the Amazon basin. It is important to consider price, customer rating, quality, and included accessories when choosing any aquarium; just because something is listed as high quality and carries a large price tag does not mean that it is the absolute best option for you.

Whether you’re upgrading from a 100 gallon fish tank or making a small downsize from a 150 gallon fish tank, a 125 gallon aquarium will fit many of your aquarium needs!

If you have any questions about 125 gallons tanks or have had success keeping your own large aquarium system, don’t hesitate to leave a comment below!

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