Aquarium Forge

100 gallon Aquarium

Everything about the 100 gallon tank: its real water volume, the fish that fit, and the heater, filter, substrate, and total weight it needs — calculated with the same tools as our calculators.

Quick Facts

Nominal Volume
100 US gallons (378.54 L)
Approximate Water Volume
83–93 gallons
Common Dimensions
60 × 18 × 21 inches
Suitable Fish
50 species in our database
Recommended Heater
300–400 W
Recommended Filter
400 GPH (1,514 LPH)

Suitable Fish

These species have a minimum tank requirement of 100 gallons or less, so they can live in a 100 gallon tank:

Stocking Examples

A balanced starting point for a 100 gallon community — 12 × Bronze Corydoras + 10 × Kuhli Loach.

Stocking status: Moderate — Bioload 70 of ~100 points for your 100-gallon tank.

Build your own plan

Filter Recommendations

For a freshwater community, target about 400 GPH (1,514 LPH) of actual turnover. The minimum sensible flow is 300 GPH.

Manufacturer flow is rated on an empty filter — real flow drops with media and head height, so choose toward the upper end.

Heater Requirements

Holding 78°F in a 68°F room needs roughly 300–400 W. A temperature rise of 10°F (5.6°C) is assumed.

Two smaller heaters (one at each end) heat more evenly and give redundancy — worth considering for larger tanks.

Substrate Amount

With a 2-inch gravel bed, a 100 gallon tank needs about 35.4 L / 2,160 cu in — roughly 59.47 kg / 131.1 lb.

Estimated Weight

Set up and filled, a 100 gallon tank weighs around 893.85 lb — including water, glass, a 2-inch gravel bed, and a small allowance for decor and equipment.

Add the stand or cabinet weight separately when checking your floor.

Compatible Equipment

  • Heater: 300–400 W (adjust for your room temperature).
  • Filter: 400 GPH (1,514 LPH) actual turnover.
  • Substrate: 35.4 L / 2,160 cu in of gravel at a 2-inch depth.
  • Lighting: match the fixture to the tank length (60 inches) and to your plants' needs.
  • Stand: rated for at least 893.85 lb.

Frequently asked questions

How many gallons does a 100 gallon aquarium actually hold?

A 100 gallon tank is rated at 100 US gallons nominal, but real water volume runs lower — typically 83–93 gallons once it is filled to the frame line and you account for substrate, rock, and equipment displacement.

What fish can live in a 100 gallon tank?

Roughly 50 of the species in our database suit a 100 gallon tank (minimum tank requirement at or below 100 gallons). Popular options include Betta, Neon Tetra, Guppy, Angelfish, Bronze Corydoras.

What filter do I need for a 100 gallon tank?

For a freshwater community, aim for about 400 GPH (1,514 LPH) of actual turnover — the minimum sensible flow is 300 GPH. Manufacturer ratings are measured on an empty filter, so size up when in doubt.

What heater wattage for a 100 gallon tank?

To hold 78°F in a 68°F room, a 100 gallon tank typically wants around 300–400 W. The exact figure depends on the temperature rise and how cold the room gets.

How much gravel does a 100 gallon tank need?

With a 2-inch bed, a 100 gallon tank needs about 35.4 L / 2,160 cu in, weighing roughly 59.47 kg / 131.1 lb.

Figures are planning estimates calculated at 68°F room → 78°F target, 90% fill, and a 2-inch gravel bed. Last reviewed: .