Aquariumsnail · freshwater
Assassin Snail: adult size, tank size & tankmates
The Assassin Snail (Anentome helena) grows to about 1.3 in (3.2 cm TL). It needs a tank at least about 10 gallons. It doesn't need a group of its own kind, at 75–80°F.
How big it really gets
Drawn to scale against common tank lengths. Green bars meet the minimum tank length from our sources.
Will it fit your tank?
Quick facts
- Adult size
- 1.3 in (3.2 cm TL)
- Minimum tank
- about 10 gallons
- Temperature
- 75–80°F
- pH
- 7.5–8
- Hardness
- 8–15 dGH
- Group size
- 1 (solitary or pair)
- With other fish
- peaceful
- With its own kind
- peaceful
- Swims
- bottom of the tank
- Diet
- carnivore
- Care level
- beginner
- Lifespan
- 2 years
Watch for: may eat baby shrimp · eats snails
Assassin Snail tankmates
Checked with the same rules as our tank builder: temperature overlap, pH and hardness, predation and mouth size, fin-nipping and temperament. Tank size is left out here; check it in the builder.
Good tankmates
- Neon TetraAdult ~1.4 in · 70–77°F
- Cardinal TetraAdult ~1.7 in · 73–84°F
- Harlequin RasboraAdult ~2.1 in · 70–82°F
- Celestial Pearl DanioAdult ~1 in · 68–79°F
- Cherry BarbAdult ~2.4 in · 68–81°F
- Black Neon TetraAdult ~1.7 in · 73–82°F
- Glowlight TetraAdult ~1.9 in · 75–82°F
- Lemon TetraAdult ~1.9 in · 68–82°F
- GuppyAdult ~2.8 in · 63–82°F
- PlatyAdult ~2.4 in · 68–79°F
Use caution
- Ember TetraAssassin Snail (pH 7.5–8) and Ember Tetra (pH 5–7) prefer different pH.
- Chili RasboraAssassin Snail (pH 7.5–8) and Chili Rasbora (pH 4–7) prefer different pH.
- Rummy-nose TetraAssassin Snail (pH 7.5–8) and Rummy-nose Tetra (pH 5.5–7) prefer different pH.
- AngelfishNeeds careAssassin Snail (pH 7.5–8) and Angelfish (pH 6–7.4) prefer different pH.
- Panda CoryAssassin Snail (pH 7.5–8) and Panda Cory (pH 6–7.4) prefer different pH.
- Pygmy CoryAssassin Snail (pH 7.5–8) and Pygmy Cory (pH 6.4–7.4) prefer different pH.
- Julii CoryAssassin Snail (pH 7.5–8) and Julii Cory (pH 5.8–7.2) prefer different pH.
- Kuhli LoachAssassin Snail (pH 7.5–8) and Kuhli Loach (pH 3.5–7) prefer different pH.
Avoid
- German Blue RamNeeds careAssassin Snail (75–80°F) and German Blue Ram (81–86°F) need different temperatures.
- White Cloud Mountain MinnowNeeds careAssassin Snail (75–80°F) and White Cloud Mountain Minnow (57–72°F) need different temperatures.
- Boesemani RainbowfishAssassin Snail (75–80°F) and Boesemani Rainbowfish (81–86°F) need different temperatures.
- Blood Parrot CichlidOutgrows tanksBlood Parrot Cichlid eats snails, including Assassin Snail.
- Clown LoachOutgrows tanksClown Loach eats snails, including Assassin Snail.
- Common / Comet GoldfishOutgrows tanksAssassin Snail and Common / Comet Goldfish only share 75–75°F. That's a tight window.
- Convict CichlidNeeds careConvict Cichlid eats snails, including Assassin Snail.
- Electric Blue AcaraNeeds careElectric Blue Acara eats snails, including Assassin Snail.
All 105 species we checked against the Assassin Snail
| Species | Verdict | Why |
|---|---|---|
| Bala Shark | Compatible | No conflicts found |
| Bamboo Shrimp | Compatible | No conflicts found |
| Betta | Compatible | No conflicts found |
| Black Neon Tetra | Compatible | No conflicts found |
| Bleeding Heart Tetra | Compatible | No conflicts found |
| Bolivian Ram | Compatible | No conflicts found |
| Bristlenose Pleco | Compatible | No conflicts found |
| Bronze Cory | Compatible | No conflicts found |
| Buenos Aires Tetra | Compatible | No conflicts found |
| Bumblebee Goby | Compatible | No conflicts found |
| Cardinal Tetra | Compatible | No conflicts found |
| Celestial Pearl Danio | Compatible | No conflicts found |
| Cherry Barb | Compatible | No conflicts found |
| Cherry Shrimp | Compatible | No conflicts found |
| Chinese Algae Eater | Compatible | No conflicts found |
| Clown Pleco | Compatible | No conflicts found |
| Common Pleco | Compatible | No conflicts found |
| Congo Tetra | Compatible | No conflicts found |
| Denison Barb | Compatible | No conflicts found |
| Dwarf Gourami | Compatible | No conflicts found |
| Dwarf Neon Rainbowfish | Compatible | No conflicts found |
| Endler's Livebearer | Compatible | No conflicts found |
| Forktail Blue-eye | Compatible | No conflicts found |
| Ghost Shrimp | Compatible | No conflicts found |
| Giant Danio | Compatible | No conflicts found |
| Glowlight Tetra | Compatible | No conflicts found |
| Guppy | Compatible | No conflicts found |
| Harlequin Rasbora | Compatible | No conflicts found |
| Head-and-tail-light Tetra | Compatible | No conflicts found |
| Honey Gourami | Compatible | No conflicts found |
| Iridescent Shark | Compatible | No conflicts found |
| Kissing Gourami | Compatible | No conflicts found |
| Kribensis | Compatible | No conflicts found |
| Lambchop Rasbora | Compatible | No conflicts found |
| Lemon Tetra | Compatible | No conflicts found |
| Molly | Compatible | No conflicts found |
| Moonlight Gourami | Compatible | No conflicts found |
| Neon Tetra | Compatible | No conflicts found |
| Odessa Barb | Compatible | No conflicts found |
| Otocinclus | Compatible | No conflicts found |
| Pearl Danio | Compatible | No conflicts found |
| Pearl Gourami | Compatible | No conflicts found |
| Penguin Tetra | Compatible | No conflicts found |
| Platy | Compatible | No conflicts found |
| Pristella Tetra | Compatible | No conflicts found |
| Rainbow Shark | Compatible | No conflicts found |
| Red-Tail Shark | Compatible | No conflicts found |
| Scissortail Rasbora | Compatible | No conflicts found |
| Serpae Tetra | Compatible | No conflicts found |
| Siamese Algae Eater | Compatible | No conflicts found |
| Silver Hatchetfish | Compatible | No conflicts found |
| Silver Tip Tetra | Compatible | No conflicts found |
| Sparkling Gourami | Compatible | No conflicts found |
| Sterbai Cory | Compatible | No conflicts found |
| Swordtail | Compatible | No conflicts found |
| Three-spot Gourami | Compatible | No conflicts found |
| Tiger Barb | Compatible | No conflicts found |
| Variatus Platy | Compatible | No conflicts found |
| Zebra Danio | Compatible | No conflicts found |
| African Dwarf Frog | Caution | Assassin Snail (pH 7.5–8) and African Dwarf Frog (pH 6.6–7.4) prefer different pH. |
| Amano Shrimp | Caution | Assassin Snail (pH 7.5–8) and Amano Shrimp (pH 6–7) prefer different pH. |
| Angelfish | Caution | Assassin Snail (pH 7.5–8) and Angelfish (pH 6–7.4) prefer different pH. |
| Black Skirt Tetra | Caution | Assassin Snail (pH 7.5–8) and Black Skirt Tetra (pH 6–7) prefer different pH. |
| Chili Rasbora | Caution | Assassin Snail (pH 7.5–8) and Chili Rasbora (pH 4–7) prefer different pH. |
| Clown Killifish | Caution | Assassin Snail (pH 7.5–8) and Clown Killifish (pH 4–7) prefer different pH. |
| Cockatoo Dwarf Cichlid | Caution | Assassin Snail (pH 7.5–8) and Cockatoo Dwarf Cichlid (pH 5–6) prefer different pH. |
| Crystal Red Shrimp | Caution | Assassin Snail and Crystal Red Shrimp only share 75–76°F. That's a tight window.; Assassin Snail (pH 7.5–8) and Crystal Red Shrimp (pH 5.8–7) prefer different pH. |
| Diamond Tetra | Caution | Assassin Snail (pH 7.5–8) and Diamond Tetra (pH 5.5–7) prefer different pH. |
| Discus | Caution | Assassin Snail and Discus only share 79–80°F. That's a tight window.; Assassin Snail (pH 7.5–8) and Discus (pH 5–7) prefer different pH. |
| Ember Tetra | Caution | Assassin Snail (pH 7.5–8) and Ember Tetra (pH 5–7) prefer different pH. |
| Glass Catfish | Caution | Assassin Snail (pH 7.5–8) and Glass Catfish (pH 4–7) prefer different pH. |
| Gold Barb | Caution | Assassin Snail and Gold Barb only share 75–75°F. That's a tight window. |
| Hillstream Loach | Caution | Assassin Snail and Hillstream Loach only share 75–75°F. That's a tight window. |
| Japanese Trapdoor Snail | Caution | Assassin Snail eats snails (that's its job as pest control), including Japanese Trapdoor Snail.; Assassin Snail (pH 7.5–8) and Japanese Trapdoor Snail (pH 6.5–7.3) prefer different pH. |
| Julii Cory | Caution | Assassin Snail (pH 7.5–8) and Julii Cory (pH 5.8–7.2) prefer different pH. |
| Kuhli Loach | Caution | Assassin Snail (pH 7.5–8) and Kuhli Loach (pH 3.5–7) prefer different pH. |
| Malaysian Trumpet Snail | Caution | Assassin Snail eats snails (that's its job as pest control), including Malaysian Trumpet Snail. |
| Marbled Hatchetfish | Caution | Assassin Snail (pH 7.5–8) and Marbled Hatchetfish (pH 4–7) prefer different pH. |
| Mystery Snail | Caution | Assassin Snail eats snails (that's its job as pest control), including Mystery Snail.; Assassin Snail (pH 7.5–8) and Mystery Snail (pH unknown) prefer different pH. |
| Nerite Snail | Caution | Assassin Snail eats snails (that's its job as pest control), including Nerite Snail. |
| Panda Cory | Caution | Assassin Snail (pH 7.5–8) and Panda Cory (pH 6–7.4) prefer different pH. |
| Peppered Cory | Caution | Assassin Snail (pH 7.5–8) and Peppered Cory (pH 6–7) prefer different pH. |
| Pygmy Cory | Caution | Assassin Snail (pH 7.5–8) and Pygmy Cory (pH 6.4–7.4) prefer different pH. |
| Ramshorn Snail | Caution | Assassin Snail eats snails (that's its job as pest control), including Ramshorn Snail. |
| Rosy Barb | Caution | Assassin Snail and Rosy Barb only share 75–75°F. That's a tight window. |
| Rummy-nose Tetra | Caution | Assassin Snail (pH 7.5–8) and Rummy-nose Tetra (pH 5.5–7) prefer different pH. |
| Tinfoil Barb | Caution | Assassin Snail (pH 7.5–8) and Tinfoil Barb (pH 6.5–7) prefer different pH. |
| Blood Parrot Cichlid | Avoid | Blood Parrot Cichlid eats snails, including Assassin Snail.; Assassin Snail (pH 7.5–8) and Blood Parrot Cichlid (pH 6.5–7.4) prefer different pH. |
| Boesemani Rainbowfish | Avoid | Assassin Snail (75–80°F) and Boesemani Rainbowfish (81–86°F) need different temperatures. |
| Clown Loach | Avoid | Clown Loach eats snails, including Assassin Snail.; Assassin Snail (pH 7.5–8) and Clown Loach (pH 5–7) prefer different pH. |
| Common / Comet Goldfish | Avoid | Assassin Snail and Common / Comet Goldfish only share 75–75°F. That's a tight window.; Common / Comet Goldfish eats snails, including Assassin Snail. |
| Convict Cichlid | Avoid | Convict Cichlid eats snails, including Assassin Snail. |
| Electric Blue Acara | Avoid | Electric Blue Acara eats snails, including Assassin Snail. |
| Electric Yellow Lab | Avoid | Electric Yellow Lab eats snails, including Assassin Snail. |
| Fancy Goldfish | Avoid | Assassin Snail (75–80°F) and Fancy Goldfish (50–70°F) need different temperatures. |
| Firemouth Cichlid | Avoid | Firemouth Cichlid eats snails, including Assassin Snail. |
| German Blue Ram | Avoid | Assassin Snail (75–80°F) and German Blue Ram (81–86°F) need different temperatures.; Assassin Snail (pH 7.5–8) and German Blue Ram (pH 4–7) prefer different pH. |
| Oscar | Avoid | Oscar eats snails, including Assassin Snail. |
| Paradise Fish | Avoid | Assassin Snail (75–80°F) and Paradise Fish (50–72°F) need different temperatures. |
| Pea Puffer | Avoid | Pea Puffer eats snails, including Assassin Snail. |
| Pictus Catfish | Avoid | Pictus Catfish eats snails, including Assassin Snail.; Assassin Snail (pH 7.5–8) and Pictus Catfish (pH 5.8–6.8) prefer different pH. |
| Upside-down Catfish | Avoid | Upside-down Catfish eats snails, including Assassin Snail. |
| Weather Loach | Avoid | Assassin Snail (75–80°F) and Weather Loach (64–74°F) need different temperatures.; Weather Loach eats snails, including Assassin Snail. |
| White Cloud Mountain Minnow | Avoid | Assassin Snail (75–80°F) and White Cloud Mountain Minnow (57–72°F) need different temperatures. |
| Yoyo Loach | Avoid | Yoyo Loach eats snails, including Assassin Snail. |
Care notes
Needs: Eats other snails including nerites and mystery snails, not just pest snails; harder water for shell health; needs protein food once pest snails are gone; eaten by puffers and snail-eating loaches
Group: Not social; separate sexes, so Co-Op suggests 6+ only if you want them to breed
Temperament: peaceful toward other fish, peaceful toward its own kind. Lives in the bottom of the tank.
Common questions
How big does a Assassin Snail get?
About 1.3 inches (3.2 cm TL) as an adult, according to aquariumcoop.com.
What size tank does a Assassin Snail need?
At least about 10 gallons. The smallest standard tank that meets that is a 10 gallon.
How many Assassin Snails should be kept together?
It can be kept on its own. Not social; separate sexes, so Co-Op suggests 6+ only if you want them to breed
What fish can live with a Assassin Snail?
Species that passed every check include Neon Tetra, Cardinal Tetra, Harlequin Rasbora, Celestial Pearl Danio, Cherry Barb, Black Neon Tetra.
Gear for a Assassin Snail setup
TankSmallest standard tank that meets its minimum: 10 gallon (20 in long).Find on Amazon →HeaterAbout 50 W for 10 gallons, holding 75–80°F.Find on Amazon →FoodMeaty frozen foods suit its diet.Find on Amazon →Test kitCheck ammonia, nitrite and pH. Cycle the tank before adding fish.Find on Amazon →
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Related guides
Sources
Values come from these pages, in our own words. Status: verified (independent spot-check). Last reviewed 2026-10-12.
- aquariumcoop.com /blogs/aquarium/assassin-snail
- fishkeepingworld.com /assassin-snail/
- aquariadise.com /caresheet-assassin-snail/
- theshrimpfarm.com /posts/assassin-snail-care/