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How Much Does A 55 Gallon Fish Tank Weigh? Aquarium Size & Weight Guide

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By Nicole Cosgrove

man cleaning aquarium using magnetic fish tank cleaner

Planning your space before setting up a fish tank entails numerous considerations, especially the tank’s final weight. Underestimating the water and structural weight can spell disaster when you put your aquarium on a poorly supported stand or if anyone tries to adjust its position. Although they weigh less than 100 pounds out of the box, a fully loaded 55-gallon fish tank can weigh over 600 pounds when full of water, gravel, and features!

Comparing tank weights before ordering your fish’s new home can prevent aggravation. We’ll help you make the best choice for your home as we look at how much a 55-gallon fish tank weighs and how that compares to various alternatives.

aquarium plant divider

How Much Does a 55-Gallon Fish Tank Weigh?

Most 55-gallon fish tanks consist of glass panels and silicone with plastic framing. The average tank will measure roughly 48” x 21” and weigh 75–100 pounds when empty. For a higher price, you can upgrade to an acrylic tank that will cut the weight almost in half.

Filling the tank adds significant weight. Fresh water weighs 8.34 pounds per gallon, putting the total water weight at roughly 459 pounds if the tank holds 55 gallons. Saltwater is slightly heavier at around 8.55 pounds, adding 11–12 pounds to a 55-gallon tank.

A 55-gallon fish tank full of water is quite hefty at roughly 525–550 pounds. Water-filled fish tanks generally weigh around 9–10 pounds per gallon.

Of course, you likely won’t leave the tank brimming full, and even if you do, there will be plenty of displacement from gravel, rocky features, and other accessories. Following the pound of gravel per gallon of water rule, you’ll add about 55 pounds of gravel to the tank.

You will also likely use stone hideaways, castles, and other ornaments that are much denser than the water. With everything involved, the final weight of the fish tank can range from 600 to 650 pounds.

Image Credit: Vojce, Shutterstock
Volume Size Empty Weight Filled Weight
20-gallon 30” L x 12” W x 12” H 25 lbs. 225 lbs.
29-gallon 30” L x 12” W x 18” H 43 lbs. 320 lbs.
40-gallon 36” L x 16” W x 16” H 55 lbs. 440 lbs.
55-gallon 48” L x 13” W x 21” H 80 lbs. 625 lbs.
65-gallon 36” L x 18” W x 24” H 125 lbs. 750 lbs.
75-gallon 48” L x 18” W x 21” H 140 lbs. 850 lbs.
90-gallon 48” L x 18” W x 24” H 160 lbs. 1050 lbs.

How Many Fish Can Go In a 55-Gallon Fish Tank?

A full 55-gallon tank can put significant strain on a table and possibly the underlying floor. Knowing the weight, you may want to double-check your requirements to ensure you need a tank this size.

The 1-inch-per-gallon rule is an easy way to ballpark the number of fish that can fit in a tank. By this generalization, a 55-gallon tank can hold enough fish to equal 55 inches in length. It’s an overly simplistic approach with several issues and primarily only works with smaller community fish. Still, some people find it a viable starting point.

More crucial than anything is considering the types of fish you want to stock to ensure they will create a healthy environment and co-exist peacefully. Too many fish will overload the aquarium with waste that beneficial bacteria won’t be able to cycle quickly enough, causing an overload of toxins in the tank.

As with any tank, you should start your 55-gallon aquarium with only a few fish and add more after 2–3 weeks when you know you have manageable nitrate levels.

Big aquarium with colorful discus fishes
Image Credit: Jules43, Shutterstock

Benefits of Using a 55-Gallon Fish Tank

While the weight can be challenging, a 55-gallon fish tank offers several advantages over small and medium-sized aquariums once you establish a sturdy enough stand. Since it’s long and narrow, it’s flexible enough to stock numerous colorful fish while giving you a better viewing experience.

With more water, the conditions tend to be more stable, staying relatively balanced through minor environmental modifications and requiring less frequent water changes.

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Final Thoughts

A 55-gallon tank is a heavy and potentially hazardous piece of equipment when filled. It will be immovable once in place, and its stand will need extra reinforcement and anchoring to ensure the load won’t tip or break the support. Before investing in a tank this size, double-check your space and assess your needs to ensure it’s the best fit.

Featured Image Credit: hedgehog94, Shutterstock

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