Silver Dollar community
- 5 × Silver Dollar
- 5 × Clown Loach
- 1 × Blood Parrot Cichlid
- 6 × Drape Fin Barb
- 1 × Blue Gourami
- 1 × Nerite Snail
77% stockedOpen in builder
Tank size guide
125Gallon Tank: Stocking Ideas, Heater & Filter Size
A 6-foot tank. Room for big schools, large cichlids, clown loaches and plecos that need the length.
- Dimensions
- 72" × 18" × 21"
- Volume
- 125 gal · 473 L
- Heater
- 375-625 W
- Filter flow
- 500-750 GPH
- Filled weight
- ~1,250 lb
- Gravel (2" bed)
- ~150 lb
- Weekly water change
- 31.3 gal (25%)
- Water weight
- 1,043 lb
125 gallon stocking ideas
Each plan passes the Tank Builder's compatibility check with no conflicts and room to spare. Open one to tweak it.
Denison Barb community
- 11 × Denison Barb
- 1 × Electric Blue Acara
- 4 × Festivum
- 6 × Red Rainbowfish
- 1 × Gold Gourami
- 3 × Amano Shrimp
70% stockedOpen in builder
Turquoise Rainbowfish community
- 12 × Turquoise Rainbowfish
- 3 × Cuckoo Catfish
- 1 × Firemouth Cichlid
- 6 × Red Rainbowfish
- 1 × Kissing Gourami
- 1 × Mystery Snail
69% stockedOpen in builder
Try it yourself
Build your own 125 gallon tank
Pick your tank size, add fish, and instantly see if they get along, how full the tank is, and the heater and filter you need.
Your fish will swim here
125 gal · 473 L
1. Tank size
gal
2. Add fish
Start with the fish you want most
Search above or tap the box for popular picks. Schooling fish come in at their minimum group size.
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Compatibility, stocking level, heater and filter sizes, and the water each fish likes all show up here as you build.
Fish that fit a 125 gallon tank
Popular freshwater species whose recommended minimum is 125 gallons or less. Check they get along in the builder before you buy.
- Neon Tetra1.5" · 10+ gal · groups of 6+
- Green Neon Tetra1" · 10+ gal · groups of 8+
- Cardinal Tetra2" · 15+ gal · groups of 6+
- Betta2.8" · 5+ gal
- Crowntail Betta2.8" · 5+ gal
- Halfmoon Betta2.8" · 5+ gal
- Peaceful Betta2" · 10+ gal
- Plakat Betta2.8" · 5+ gal
- Guppy2.4" · 10+ gal · groups of 3+
- Bronze Cory2.8" · 20+ gal · groups of 6+
- Panda Cory2" · 20+ gal · groups of 6+
- Platy2.5" · 10+ gal · groups of 3+
- Molly4.5" · 20+ gal · groups of 3+
- Sailfin Molly5" · 30+ gal · groups of 3+
- Zebra Danio2" · 10+ gal · groups of 6+
- Harlequin Rasbora1.8" · 15+ gal · groups of 8+
- Ember Tetra0.8" · 10+ gal · groups of 8+
- Cherry Shrimp1.5" · 5+ gal · groups of 10+
- Otocinclus1.6" · 10+ gal · groups of 6+
- Bristlenose Pleco5" · 30+ gal
- Albino Bristlenose Pleco5" · 30+ gal
- Honey Gourami2" · 10+ gal
- Dwarf Gourami3.5" · 15+ gal
- Pearl Gourami4.5" · 30+ gal
Popular fish that need more than 125 gallons
125 gallon tank FAQ
How many fish can go in a 125 gallon tank?
It depends on the fish, not a fixed number. A good example for a 125 gallon is 5 Silver Dollar, 5 Clown Loach, 1 Blood Parrot Cichlid, 6 Drape Fin Barb, 1 Blue Gourami, 1 Nerite Snail, which comes to about 77% of a cautious stocking limit. Small, tidy fish like tetras and rasboras let you keep more; messy fish like goldfish and plecos fill a tank much faster.
What size heater do I need for a 125 gallon tank?
A 375 to 625 watt heater. Go toward 625 W if the room runs cool. At this size, two smaller heaters at opposite ends are safer and heat more evenly than one big one.
What size filter does a 125 gallon tank need?
Look for 500 to 750 gallons per hour of flow. For messy fish or a busy tank, go up to about 1000 GPH.
What are the dimensions of a 125 gallon tank?
A standard 125 gallon is about 72" long, 18" wide and 21" tall. Brands vary slightly, so measure before buying a stand or lid.
How much does a 125 gallon tank weigh?
The water alone weighs about 1,043 lb. With glass, gravel and decor, plan on roughly 1,250 lb, so use a stand made for aquariums.