FishTank40 gallon breeder stocking ideas
The 40 gallon breeder is a favorite with fishkeepers. At 36 inches long and 18 inches front to back, it has a wide, deep floor that gives you room for bottom dwellers, plants and aquascaping. Here are six setups that work, each checked with the free stocking calculator.
40 gallon breeder basics
- Size: about 36 × 18 × 16 inches.
- Weight: about 465 pounds when set up. Use a stand made for its 36 × 18 inch footprint. Check with the tank weight calculator.
- Heater: 100–200 W depending on how cold your room gets, and 125 W suits most rooms. Check with the heater calculator.
- Filter: one rated for 40 gallons or more. See the best aquarium filters.
- Substrate: about 75 pounds for 2 inches. Work out your amount with the substrate calculator.
Why a breeder instead of a 40 tall?
Fish use floor space and surface area more than height. The breeder's 18 inch depth gives more surface for oxygen, more room for schools to swim and more space to arrange rocks and plants. The trade-off is that it's only 16 inches tall, so very tall fish like adult angelfish are happier in a 55 gallon.
1. Peaceful community
8 harlequin rasboras · 6 bronze corydoras · 1 honey gourami
Keep at 72–78°F · 75% stocked in the calculator
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Calm, easy and colorful. The wide floor gives the corydoras plenty of room to forage.
2. Angelfish tank
1 angelfish · 6 bronze corydoras · 1 bristlenose pleco
Keep at 76–78°F · 76% stocked in the calculator
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A single angelfish makes a calm centerpiece. Keep it at 76–78°F for the corydoras. See angelfish care.
3. Molly tank
4 mollies · 1 bristlenose pleco · 1 nerite snail
Keep at 72–78°F · 64% stocked in the calculator
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One male to three females. Mollies like hard water. See molly care.
4. Nano fish and shrimp
20 cherry shrimp · 12 ember tetras · 8 pygmy corydoras · 6 otocinclus
Keep at 73–79°F · 52% stocked in the calculator
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Lots of tiny fish and a shrimp colony that will grow. Plant it heavily so baby shrimp have cover.
5. Cooler water tank
10 zebra danios · 10 white clouds
Keep at 65–72°F · 70% stocked in the calculator
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Fast, hardy fish that like cooler water, around 68–72°F. A lid matters, because danios jump.
6. Fancy goldfish
2 fancy goldfish
Keep at 65–72°F · 70% stocked in the calculator
Open this plan in the calculator
The wide footprint suits goldfish well. They need a strong filter and weekly water changes. See goldfish care.
What not to put in a 40 breeder
- Common plecos, which grow over a foot long. A bristlenose stays about 5 inches.
- Oscars and big cichlids, which need 75 gallons or more.
- Common and comet goldfish, which belong in a pond.
- Small fish with angelfish, such as neons and embers, which become food.
Stocking tips
- Cycle first. See how to cycle a new fish tank.
- Add fish in stages, a group at a time, a week or two apart.
- Plan your own mix with the free stocking calculator. It checks group sizes, temperatures and tankmates.
Gear for a 40 gallon breeder
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- HeaterEHEIM Jager 125 W heaterThe right size for a 40 gallon in most rooms. Check your size with the free heater calculator.
- FilterFluval AquaClear AC70 filterA hang-on-back filter rated for 40–70 gallons.
- Water changerPython No Spill Clean and Fill, 25 ftDrains and refills from your sink, so water changes need no buckets.
Related: 29 gallon stocking ideas · 55 gallon stocking ideas · Best aquarium stands