Best saltwater fish for a 40 gallon tank
A 40 gallon saltwater tank holds a clownfish pair and three or four more small fish. It also fits a school of eight green chromis over a jawfish. The saddleback clownfish, the canary fang blenny and the yellow coris wrasse start here at 40 gallons (150 liters). Every fish in the list is widely sold, rated for community tanks and lists a minimum tank of 40 gallons or less.
Keeping a freshwater tank? Freshwater fish for a 40 gallon tank →
At a glance
- Tank size
- 5–40 gal
- 5 gal (19 L) to 40 gal (150 L); half the list needs 29 gal (110 L) or more
- Temperature
- 73–81°F
- 23–27°C, most of the list
- pH
- 8.1–8.4
- Most of the list
- Difficulty
- 31 easy
- 3 medium
- Temperament
- 19 peaceful
- 15 mostly peaceful
- Reef safety
- 31 reef safe
- 3 reef safe with caution
34 species
New at this size
What a 40 gallon adds over a 30
The saddleback clownfish lists 40 gallons (150 liters) and grows to 5.1 inches (13 cm). The canary fang blenny and the yellow coris wrasse list 40 gallons as well. Eight green chromis over a pearly jawfish read comfortable here, and heavy in a 30 gallon.
Saddleback clownfish
Amphiprion polymnus
Saltwater- Size
- 5.1 in (13 cm)
- Tank
- 40 gal (150 L)
- Water
- 75–82°F (24–28°C)
Canary fang blenny
Meiacanthus oualanensis
Saltwater- Size
- 3.9 in (10 cm)
- Tank
- 40 gal (150 L)
- Water
- 72–79°F (22–26°C)
Yellow coris wrasse
Halichoeres chrysus
Saltwater- Size
- 4.7 in (12 cm)
- Tank
- 40 gal (150 L)
- Water
- 73–81°F (23–27°C)
Green chromis
Chromis viridis
Saltwater- Size
- 3.1 in (8 cm)
- Tank
- 30 gal (115 L)
- Water
- 75–82°F (24–28°C)
Pearly jawfish
Opistognathus aurifrons
Saltwater- Size
- 3.9 in (10 cm)
- Tank
- 29 gal (110 L)
- Water
- 73–81°F (23–27°C)
Clark's clownfish
Amphiprion clarkii
Saltwater- Size
- 5.5 in (14 cm)
- Tank
- 30 gal (115 L)
- Water
- 75–82°F (24–28°C)
Stocking plans
Three ways to stock a 40 gallon tank
Each plan below ran through the stocking calculator, which reads every fish at its adult size against its minimum tank. Open one to change the counts or swap in your own fish.
Clark's clownfish with a yellow assessor
ComfortableLightComfortableFullHeavyOverstockedThese species overlap at 75–79°F (24–26°C), pH 8.1–8.4.
Clownfish over a watchman goby and firefish
- 2Ocellaris clownfish
- 1Yellow watchman goby
- 2Firefish
- 1Royal gramma
- 2Skunk cleaner shrimp
- 2Mexican turbo snail
ComfortableLightComfortableFullHeavyOverstockedThese species overlap at 75–81°F (24–27°C), pH 8.1–8.4.
A green chromis school with a jawfish
ComfortableLightComfortableFullHeavyOverstockedThese species overlap at 75–79°F (24–26°C), pH 8.1–8.4.
By the numbers
Smallest
Largest
Most peaceful
Fits a 20 gallon tank
Fits a 30 gallon tank
FAQ
Common questions
How many fish can go in a 40 gallon saltwater tank?
A 40 gallon reef holds a clownfish pair with three or four more small fish, or a school of eight green chromis over a jawfish. Adult size sets the count, so two Clark's clownfish take more room than two ocellaris. Check any mix in the stocking calculator before you buy.
Is a 40 gallon breeder good for a reef tank?
A 40 gallon breeder holds the same volume as any 40 gallon tank, so every fish on this page fits it. Its footprint is wider than a standard 40, which leaves more sand for a jawfish or a watchman goby.
Can a yellow tang live in a 40 gallon tank?
No. The yellow tang lists 100 gallons (380 liters). The tomini tang, the one tang on these pages, starts at 70 gallons (265 liters).
Why is the six-line wrasse not on this list?
The six-line wrasse lists 29 gallons (110 liters), but it is marked with a tank mate caution, so it stays off these community lists.
Index
All saltwater fish for a 40 gallon tank
Azure damsel
Chrysiptera hemicyanea
Saltwater2.8 in (7 cm) · 29 gal (110 L)75–81°F (24–27°C)
Banggai cardinalfish
Pterapogon kauderni
Saltwater3.1 in (8 cm) · 29 gal (110 L)73–82°F (23–28°C)
Barber goby
Elacatinus figaro
Saltwater1.6 in (4 cm) · 11 gal (40 L)72–79°F (22–26°C)
Blackbelly dwarfgoby
Eviota atriventris
Saltwater0.8 in (2 cm) · 5 gal (19 L)72–79°F (22–26°C)
Broadstripe cleaner goby
Elacatinus prochilos
Saltwater1.6 in (4 cm) · 11 gal (40 L)72–79°F (22–26°C)Canary fang blenny
Meiacanthus oualanensis
Saltwater3.9 in (10 cm) · 40 gal (150 L)72–79°F (22–26°C)
Chalk bass
Serranus tortugarum
Saltwater3.1 in (8 cm) · 29 gal (110 L)72–81°F (22–27°C)
Cinnamon clownfish
Amphiprion melanopus
Saltwater4.7 in (12 cm) · 30 gal (115 L)75–82°F (24–28°C)
Citron clown goby
Gobiodon citrinus
Saltwater2.6 in (6.5 cm) · 11 gal (40 L)72–81°F (22–27°C)Clark's clownfish
Amphiprion clarkii
Saltwater5.5 in (14 cm) · 30 gal (115 L)75–82°F (24–28°C)
Disco blenny
Meiacanthus smithi
Saltwater3.1 in (8 cm) · 26 gal (100 L)73–81°F (23–27°C)
Firefish
Nemateleotris magnifica
Saltwater3.5 in (9 cm) · 20 gal (75 L)72–81°F (22–27°C)
Forktail fang blenny
Meiacanthus atrodorsalis
Saltwater4.3 in (11 cm) · 30 gal (114 L)72–79°F (22–26°C)Green chromis
Chromis viridis
Saltwater3.1 in (8 cm) · 30 gal (115 L)75–82°F (24–28°C)
Lined blenny
Ecsenius lineatus
Saltwater3.5 in (9 cm) · 20 gal (75 L)72–79°F (22–26°C)
Neon goby
Elacatinus oceanops
Saltwater2 in (5 cm) · 11 gal (40 L)72–79°F (22–26°C)
Ocellaris clownfish
Amphiprion ocellaris
Saltwater3.1 in (8 cm) · 20 gal (75 L)75–82°F (24–28°C)
Orange skunk clownfish
Amphiprion sandaracinos
Saltwater5.5 in (14 cm) · 30 gal (115 L)75–82°F (24–28°C)
Pajama cardinalfish
Sphaeramia nematoptera
Saltwater3.1 in (8 cm) · 29 gal (110 L)72–81°F (22–27°C)Pearly jawfish
Opistognathus aurifrons
Saltwater3.9 in (10 cm) · 29 gal (110 L)73–81°F (23–27°C)
Percula clownfish
Amphiprion percula
Saltwater3.1 in (8 cm) · 20 gal (75 L)75–82°F (24–28°C)
Pink skunk clownfish
Amphiprion perideraion
Saltwater3.9 in (10 cm) · 30 gal (115 L)75–82°F (24–28°C)
Purple firefish
Nemateleotris decora
Saltwater3.5 in (9 cm) · 20 gal (75 L)72–79°F (22–26°C)
Queensland dwarfgoby
Eviota queenslandica
Saltwater0.9 in (2.4 cm) · 10 gal (38 L)72–79°F (22–26°C)
Randall's assessor
Assessor randalli
Saltwater3.1 in (8 cm) · 29 gal (110 L)73–81°F (23–27°C)
Royal gramma
Gramma loreto
Saltwater3.1 in (8 cm) · 29 gal (110 L)72–81°F (22–27°C)Saddleback clownfish
Amphiprion polymnus
Saltwater5.1 in (13 cm) · 40 gal (150 L)75–82°F (24–28°C)
Tailspot blenny
Ecsenius stigmatura
Saltwater2.4 in (6 cm) · 20 gal (75 L)72–79°F (22–26°C)
Tomato clownfish
Amphiprion frenatus
Saltwater5.5 in (14 cm) · 30 gal (115 L)75–82°F (24–28°C)
Yellow assessor
Assessor flavissimus
Saltwater2.8 in (7 cm) · 29 gal (110 L)72–79°F (22–26°C)
Yellow cardinalfish
Ostorhinchus luteus
Saltwater2 in (5 cm) · 20 gal (75 L)73–79°F (23–26°C)
Yellow clown goby
Gobiodon okinawae
Saltwater1.6 in (4 cm) · 11 gal (40 L)73–81°F (23–27°C)Yellow coris wrasse
Halichoeres chrysus
Saltwater4.7 in (12 cm) · 40 gal (150 L)73–81°F (23–27°C)
Yellow watchman goby
Cryptocentrus cinctus
Saltwater3.5 in (9 cm) · 20 gal (75 L)72–81°F (22–27°C)
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