Quick answer: A standard 55 gallon fish tank measures 48 x 13 x 21 inches (122 x 33 x 53 cm), holds about 208 liters, and weighs around 75 to 80 pounds empty and roughly 600 to 650 pounds once it’s filled with water, substrate and decor. That weight means it needs a proper aquarium stand on a level, solid floor. It’s a great size for a big community tank, a group of angelfish, schooling barbs or rainbowfish. What most people get wrong is the shape. A 55 is long and tall but only 13 inches front to back, so it’s perfect for active schooling fish but cramped for big cichlids, plecos and fish like silver dollars that need more width.
55 gallon fish tank at a glance
| Detail | Standard 55 gallon tank |
|---|---|
| Dimensions | 48 x 13 x 21 in (122 x 33 x 53 cm) |
| Outside size with trim | About 48.25 x 12.75 x 21 in, depending on brand |
| Volume | About 55 US gallons (208 L), 47 to 50 gallons of real water after substrate and decor |
| Footprint | 4 ft long, about 1 ft deep |
| Empty weight | About 75 to 80 lb (34 to 36 kg) for glass |
| Filled weight | About 600 to 650 lb (270 to 295 kg) |
| Heater | 200 to 250 W, or two 100 to 150 W heaters |
| Filter | Rated for 55 to 75 gal, about 250 to 500 gallons per hour (GPH) |
| Light | A 48 in LED fixture |
| Substrate | About 60 to 75 lb for a 2 in layer |
| Weekly water change | 25 percent, about 12 to 14 gallons |
| Best for | Community fish, angelfish, schooling barbs, rainbowfish, gouramis |
55 gallon tank dimensions compared with other large tanks
| Tank | Dimensions (L x W x H) | Metric | Filled weight | Best for |
|---|---|---|---|---|
| 40 gallon breeder | 36 x 18 x 16 in | 91 x 46 x 41 cm | About 450 lb | Bottom dwellers, shrimp, small cichlids |
| 55 gallon | 48 x 13 x 21 in | 122 x 33 x 53 cm | About 625 lb | Schooling fish, angelfish, community tanks |
| 75 gallon | 48 x 18 x 21 in | 122 x 46 x 53 cm | About 850 lb | Larger fish, silver dollars, big planted aquascapes |
| 90 gallon | 48 x 18 x 24 in | 122 x 46 x 61 cm | About 1,050 lb | Tall fish like large angelfish |
| 125 gallon | 72 x 18 x 21 in | 183 x 46 x 53 cm | About 1,400 lb | Large cichlids, red hook silver dollars |
Here’s the honest part most 55 gallon guides leave out. The 55 and the 75 gallon have the same length and height. The only difference is 5 extra inches of depth, yet that turns a narrow tank into one that can hold far bigger fish and a much nicer aquascape. If you’re choosing between them and have the floor space and budget, the 75 is often the better buy. If you want lots of small, active schooling fish, the 55 is perfect, and it’s one of the cheapest large tanks to find, new or used.
Check your own tank’s real volume with our aquarium volume calculator. The math: 48 x 13 x 21 inches is 13,104 cubic inches, divided by 231 gives about 56.7 US gallons.
How much does a 55 gallon fish tank weigh?
| Part | Approximate weight |
|---|---|
| Empty glass tank | 75 to 80 lb |
| Water (about 50 gallons after decor) | About 415 to 460 lb |
| Substrate (2 in layer) | 60 to 75 lb |
| Rocks, wood and equipment | 20 to 50 lb |
| Total filled | About 600 to 650 lb |
That’s about the weight of three or four adults standing in one small spot, all the time. Acrylic tanks are lighter empty, but the filled weight is almost the same, since water is most of it.
55 gallon fish tank stand
Use a stand made for aquariums. A dresser, bookshelf or table usually isn’t built for 600+ pounds and can sag or collapse over time.
- Rated for at least 55 gallons, ideally with some margin.
- Matches the footprint. The stand top should be at least 48 x 13 inches, and the tank’s full bottom frame must sit on it with no overhang.
- Level. Check both directions with a spirit level before filling. Uneven support stresses the seams.
- Solid floor. On a wooden floor, place the tank along or across joists near a load-bearing wall, not in the middle of a room. Concrete floors are ideal.
- Room for equipment. A cabinet stand hides a canister filter and supplies.
DIY stands made from 2×4 lumber are popular and strong if built well, but follow a proven plan rather than guessing.
How many fish in a 55 gallon tank?
For small community fish that stay under 2 inches, a well-filtered, planted 55 gallon can hold roughly 30 to 40 fish spread across a few species. For medium fish like angelfish and gouramis, think in smaller numbers.
Why the inch per gallon rule misleads. It ignores adult size, body shape and activity. Forty 1 inch tetras are fine. Two 20 inch plecos are not, even though the inches add up the same. Plan around adult size, swimming room and group size. Our aquarium stocking calculator helps you check.
Best fish for a 55 gallon tank
| Fish | Adult size | How many in 55 gal | Notes |
|---|---|---|---|
| Angelfish | 6 in long, 8 in tall | 4 to 6, or a pair | The 21 in height suits them well |
| Tiger barbs | 3 in | 8 to 12 | Keep a big group to spread out nipping |
| Cherry barbs | 2 in | 10 to 15 | Peaceful, colorful, great with plants |
| Boesemani and other rainbowfish | 3 to 4 in | 6 to 8 | Love the 48 in swimming length |
| Black skirt tetras | 2.5 in | 8 to 10 | Hardy, best in bigger groups |
| Neon, cardinal and ember tetras | 1 to 2 in | 15 to 25 | Big schools look stunning in a long tank |
| Honey gourami or pearl gourami | 2 to 4.5 in | 3 to 5 | Calm centerpiece fish |
| Corydoras, including panda cories | 1 to 2.5 in | 8 to 12 | Use sand. Keep one species per group |
| Bristlenose pleco | 4 to 5 in | 1 to 2 | The best pleco for this size |
| Fancy goldfish | 6 to 8 in | 2 to 3 | Coldwater only, needs strong filtration |
55 gallon tank stocking ideas
| Setup | Stocking |
|---|---|
| Classic community | 15 neon or cardinal tetras, 10 cherry barbs, 3 honey gouramis, 8 corydoras, 1 bristlenose pleco |
| Angelfish tank | 5 angelfish, 12 black skirt or rummy nose tetras, 8 corydoras, 1 bristlenose pleco |
| Active barb tank | 12 tiger barbs, 6 rainbowfish, 8 corydoras, 1 bristlenose pleco |
| Rainbowfish tank | 8 boesemani rainbowfish, 10 cherry barbs, 8 corydoras |
| Fancy goldfish tank | 2 to 3 fancy goldfish, no tropical fish, extra filtration |
Fish to avoid in a 55 gallon tank
| Fish | Why not | Better tank |
|---|---|---|
| Oscars | Grow 12 in or more, messy and heavy-bodied | 75 to 125 gal |
| Common pleco | Can grow over 12 to 18 in | 125 gal or more. See our pleco guide |
| Silver dollars | Need width and a big group | 75 gal or more |
| Large cichlids like the green terror | Territorial and need floor space | 75 gal or more |
| Clown loaches | Grow 8 to 12 in in groups | 125 gal or more |
| Common and comet goldfish | Grow 10 to 12 in and more | Ponds |
| Kissing gourami | Grows large and can be pushy | 75 gal or more |
Best equipment for a 55 gallon fish tank
Filter. Choose a filter rated for 55 to 75 gallons, roughly 250 to 500 GPH. A canister filter is ideal for a 55. Two hang-on-back filters, one at each end, also work well and give better flow along the full 4 feet.
Heater. 200 to 250 watts, or two 100 to 150 W heaters at opposite ends. Two smaller heaters spread the heat evenly and act as a backup if one fails.
Light. A 48 inch LED. A basic light grows low light plants like anubias, java fern and crypts. Brighter planted-tank lights let you grow stem plants and carpets.
Lid. Glass or mesh lids stop jumpers and slow evaporation.
Substrate. About 60 to 75 lb for a 2 inch layer. Use sand for corydoras.
Water change tools. Changing 12 to 14 gallons by bucket is hard work. A long hose water changer that connects to a faucet makes weekly maintenance much easier.
About 55 gallon kits. Kits are good value for the tank and lid, but the included filter is often underpowered and the light weak for plants. Plan to upgrade those two.
How to set up a 55 gallon fish tank
- Choose the spot carefully. You can’t move a filled 55. Pick a level floor near an outlet, away from windows and heaters.
- Assemble and level the stand, then place the empty tank on it.
- Add substrate, rinsed, sloped higher at the back.
- Place hardscape and plants. Leave an open swimming lane along the front.
- Fill with dechlorinated water and check for leaks over 24 hours.
- Install the filter and heaters and turn them on.
- Cycle the tank for 3 to 6 weeks. See our how to cycle a fish tank guide.
- Add fish in stages, starting with hardy schooling fish, a group every week or two.
Our fish tank setup guide covers each step in more detail.
Water parameters and maintenance
| Parameter | Target for most tropical community fish |
|---|---|
| Temperature | 74 to 80 F (23 to 27 C) |
| pH | 6.5 to 7.5 |
| Ammonia and nitrite | 0 ppm |
| Nitrate | Under 20 to 40 ppm |
| Water change | 25 percent weekly |
Use our water change calculator to work out amounts.
Common 55 gallon tank problems
Dead spots and debris in the corners. One filter at one end can’t move water along 4 feet. Add a second filter or a small powerhead at the other end.
Uneven temperature. One heater at one end leaves the other end cooler. Use two heaters.
Cloudy water after setup. Usually a bacterial bloom while the tank cycles. See our cloudy fish tank water guide.
Algae. Too much light or direct sun. Run lights 6 to 8 hours and add more plants. For stubborn algae, see our black beard algae guide.
Water spots or drips under the tank. Check seams right away. A slow leak can become a fast one under 600 pounds of pressure.
Big fish looking cramped. The 13 inch depth is too narrow for them. Rehome or upgrade to a 75 or larger.
FAQ
What are the dimensions of a 55 gallon fish tank?
A standard 55 gallon tank is 48 inches long, 13 inches wide and 21 inches tall (122 x 33 x 53 cm).
How long is a 55 gallon fish tank?
48 inches, or 4 feet (122 cm).
How much does a 55 gallon fish tank weigh?
About 75 to 80 pounds empty and roughly 600 to 650 pounds when filled with water, substrate and decor.
How many fish can go in a 55 gallon tank?
Roughly 30 to 40 small community fish under 2 inches, or fewer medium fish like angelfish and gouramis. Plan by adult size, not the inch per gallon rule.
What size stand do I need for a 55 gallon tank?
An aquarium stand rated for at least 55 gallons, with a top at least 48 x 13 inches so the whole bottom frame is supported.
Is a 55 gallon tank good for beginners?
Yes. Bigger tanks are more stable than small ones. The main challenges are weight, cost and the work of larger water changes.
What size heater and filter do I need for a 55 gallon tank?
A 200 to 250 W heater, or two 100 to 150 W heaters, and a filter rated for 55 to 75 gallons, about 250 to 500 GPH.
55 gallon vs 75 gallon: which is better?
They’re the same length and height, but the 75 is 5 inches deeper. The 75 suits larger fish and aquascapes, while the 55 is great for schooling community fish.
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