Assassin Snail Care Guide: Care, Diet, Behavior, Parameters, Habitat, Health.

Assassin Snail Care Guide

The Assassin Snail (Clea Helena) is one of the most commonly kept freshwater snails in the aquarium hobby. Assassin snails are great at keeping pest snail populations in check such as unwanted Bladder snails, Pond snails, Malaysian Trumpet Snails (MTS) or Ramshorn snails. 

Table of Contents

1. Care difficulty, size, water parameters, aquarium size, origin, lifespan, appearance.

2. Diet: main diet, supplemental foods, scavenging.

3. Habitat: substrate, tank size, aquascape/layout, lighting.

4. Keeping live plants with assassin snails

5. Keeping shrimp with assassin snails

6. Tankmates: Suitable tankmates and tankmates to avoid

7. Breeding and reproduction: Mating behavior, eggs, incubation, hatching.

8. Health issues and general prevention

9. Toxic substances: chemicals and medications

10. Purchasing in store vs online

 

Assassin Snail (Clea Helena) key points:

• Natural and effective pest control - Their most popular use is controlling populations of pest snails like bladder, pond, or ramshorn snails. Assassin snails hunt and consume these snails, helping to prevent overpopulation without the need for chemicals or manual removal.
• Extremely low risk of overpopulation - Unlike pest snails or Mystery Snails that reproduce rapidly, assassin snails breed slowly and require both a male and female to reproduce. This means they’re unlikely to overrun your tank.
• Substrate cleaning - They bury themselves in the substrate while hunting, which gently stirs the tank bed. This can help prevent compacting and dead zones in the substrate, promoting better tank health.
• Peaceful toward other species - Assassin snails only target smaller snails or protein-based food. They’re peaceful toward fish, large shrimp, plants, and even bigger snails such as big nerite snails or rabbit snails, making them safe for most community tanks.
• Aesthetic appeal - With their distinctive striped shells and interesting behavior, they add a unique visual and behavioral element to aquariums.
• Low maintenance - Once they’re established, assassin snails are relatively low maintenance. They don’t require extra care beyond ensuring clean water conditions and providing them with occasional protein-based foods if no snails are available for them to hunt.

 

 

Assassin snail care difficulty 

Caring for Assassin Snails (Clea helena) is generally easy and suitable for beginner to intermediate aquarists. As long as you provide good water quality and maintain stable parameters within an acceptable range, you won’t have any issues. We’ll dive more into it below.

 

Assassin snail size

Assassin snails are slow growers compared to some other species, so it can take several months (sometimes up to a year) for them to reach their full adult size.

Assassin snails (Clea helena) can grow to about 1 to 1.25 inches in length when fully mature. This size is typical for adults, with juveniles being much smaller when they first hatch.

Their size makes them well-suited for most aquariums, as they won't grow too large or become overwhelming in terms of space requirements.

Although they stay relatively small and do extremely well in groups, avoid overcrowding.

 

Water parameters. Stability is everything!

Although assassin snails can adjust and thrive is a wide variety of water parameters, there is always an ideal range which you should try to match at all times and provide a stable environment. In addition, you should always make sure your aquarium is fully cycled and heated before adding any snails.

Temperature: 74°F to 80°F (24°C to 27°C)

pH: 6.7 to 7.8

Hardness: 6-15 dGH 

Ammonia/Nitrites: 0 ppm 

Nitrates: Under 10 ppm

Water Flow: Slow to moderate

 

 

Assassin snail habitat and tank size

The ideal habitat for Clea helena (assassin snails) should mimic their natural environment and provide them with ample space and resources to thrive:

1. Substrate

• Fine Gravel or Sand: These snails like to burrow and move around the substrate in search of food, especially pest snails. Fine gravel or sand is ideal for this, as it won’t damage their bodies and allows easy movement. Plant substrate such as CaribSea Eco-complete, or Aquavitrum Aquasolum are great as well.

2. Aquarium Size

• Minimum 10 Gallons: While assassin snails are small, they still need enough space to roam. A 10-gallon tank is suitable for a small group. If you want to keep multiple snails or have more tankmates, opt for a larger tank.

3. Water Quality and stable parameters

• Clear and Clean: Snails need to be well kept and cared for so you need a well-maintained tank. Use a gentle filtration system to ensure there are no sharp currents that could stress them. A sponge filter is often best because it provides filtration without disturbing the water too much but a hang on or canister is fine too depending on the aquarium size.

4. Aquascaping

• Rocks and Driftwood: Assassin snails enjoy hiding in crevices and exploring different areas of the tank. Use rocks, driftwood, and structures that provide hiding spots and places for them to scavenge.
• Live Plants: While assassin snails don’t rely heavily on plants, having some live plants (like Anubias, Java fern, Mosses, etc) can improve the aesthetics of the tank and give snails a more natural environment. Plants also help stabilize water parameters by absorbing nitrates.

7. Lighting

• Moderate Lighting: While assassin snails are not particularly light-sensitive, moderate lighting will help plants in the tank to thrive. Keep the lighting on a 8-9 hour cycle.

This habitat setup will encourage healthy, active assassin snails while helping to maintain a balanced aquarium environment.

Scientific name and origin

Scientific name: Clea Helena

Origin: Native to Southeast Asia, particularly in countries like Thailand, Vietnam, and Malaysia. They are typically found in slow-moving freshwater streams, rivers, and ponds, where they scavenge for food, primarily other snails. Their natural environment often has soft, muddy substrates, making them well-suited for burrowing.

 

Assassin snail lifespan

The lifespan of the Assassin Snail typically ranges from 2 to 3 years in captivity, although some can live longer under ideal conditions. Their lifespan can be influenced by factors like water quality, diet, temperature, and overall tank environment. Proper care, such as maintaining stable water parameters and providing a healthy diet, can help maximize their lifespan.

Assassin snail diet

Assassin snails are carnivorous and primarily feed on other snails. In the wild, they hunt and scavenge for small, slow-moving snails like bladder snails, pond snails, and ramshorn snails. They use their sharp radula (a tooth-like structure) to pierce and consume the soft tissue inside.

The diet of an assassin snail (Clea helena) primarily consists of meat from other snails or meaty supplemented foods.

Here’s a breakdown of their typical diet:

1. Snails (Main Diet)

• Pest Snails: Assassin snails are natural hunters and will prey on small, slow-moving snails like bladder snails, pond snails, and ramshorn snails. 

2. Supplemental Foods:

If pest snails are not available in the tank, assassin snails can be fed alternative protein sources, such as:

• Frozen or live meaty foods: Bloodworms, brine shrimp, and daphnia can provide the necessary protein.
• Sinking fish food: They may also scavenge sinking pellets or wafers meant for bottom-dwelling fish.
• Carnivorous snail foods: Some aquarium stores sell specific foods formulated for carnivorous snails, which can be a good supplement.

 

3. Occasional Scavenging:

• Organic Debris: Assassin snails are opportunistic scavengers and will sometimes feed on decaying plant matter or leftover food, although this is not a major part of their diet.

In an aquarium, it's important to provide a balance of snail prey and protein-based foods to ensure that assassin snails stay healthy and active. Do not to overfeed them with fish food, as their main diet should come from hunting other snails or protein-rich supplements.

 

Assassin snail appearance 

Assassin snails have a distinctive and striking appearance.

Shell

• Shape: Their shells are conical and slightly elongated, resembling a classic "turret" shape, which is typical of many freshwater snails.
• Color: The shell is generally light brown to yellowish-brown, with dark spiral bands running across the shell. The color pattern can vary, with some individuals having more pronounced striping or darker tones.
• Size: They grow to around 1 inch in length, making them a small-sized snail species in aquariums.

Body

• Color: The soft body of the assassin snail is typically translucent white or light yellow, which contrasts with the darker shell. This can sometimes give them a somewhat ghostly appearance, especially when they are resting or moving slowly.
• Tentacles: They have two pairs of tentacles. The longer tentacles are used for sensory purposes, while the shorter ones near the head are used for feeding and detecting food.
• Movement: Assassin snails move slowly and gracefully, often gliding across the substrate in search of food or hiding places.

Distinct Features:

• Radula: Like other snails, assassin snails have a radula (a tooth-like structure) that they use to scrape and pierce their prey. This tool is crucial for their carnivorous feeding habits.
• Eyes: Their eyes are located at the tips of the longer tentacles, giving them a typical snail appearance.

Overall Aesthetic:

The combination of their striped shell and light-colored body makes assassin snails quite attractive in an aquarium setting, and their interesting predatory behavior adds a unique dynamic to the tank.

 

Keeping live plants with assassin snails

Live plants can be kept with Assassin Snails (Clea Helena) in the same tank. The snails are not plant eaters, so they won't damage or consume live plants. However, there are some considerations to keep in mind to ensure a harmonious setup:

Snail Behavior

• Non-Plant Eaters: Assassin Snails are carnivorous and primarily feed on other snails and detritus. They do not typically eat live plants, so you don’t need to worry about them damaging or uprooting your plants.
• Movement: Assassin Snails tend to move slowly and are not very active compared to other species of snails. They’re more likely to crawl along rocks, glass, and plants without causing harm.

Tank Conditions

• Plant-friendly Water Parameters: Assassin Snails are tolerant of a wide range of water conditions, but it's essential to keep the tank stable.
• Water Flow: While Assassin Snails prefer slower-moving water, plants often benefit from gentle water flow. Ensure you have an appropriate filter setup that won’t disturb delicate plants but provides enough water circulation for the snails and plants to thrive.

Plant Care

• Potential for snail movement on plants: While Assassin Snails don't eat plants, they may occasionally climb over plant leaves or roots. However, they are unlikely to damage the plants in the process.
• Algae Control: If you have algae on your plants, Assassin Snails might help to clean up some of the excess algae, but they are not as efficient as other species of snails in this regard. That being said, having a few Assassin Snails won’t harm your plants and may actually help keep any pest snail populations under control that might also be feeding on your plants.

You can absolutely keep live plants with Assassin Snails. These snails will not eat or damage your plants, and they will help with controlling pest snail populations. Just ensure the tank conditions are optimal for both your plants and snails, and you should have a thriving, balanced aquarium.

 

Keeping shrimp with assassin snails

Yes, shrimp can generally be kept with Assassin Snails (Clea Helena), but there are a few important factors to consider to ensure both species thrive together:

Shrimp Size

• Adult Shrimp: Larger or adult shrimp (such as big neocaridina shrimp, bamboo shrimp, vampire shrimp, Ghost Shrimp) are typically safe from Assassin Snails. These snails mainly target snails, particularly small or weaker ones, and will not usually hunt shrimp unless hungry. However, it's always a good idea to keep an eye on any aggressive behavior, especially with smaller shrimp.
• Baby Shrimp: Baby shrimp or juvenile shrimp could be at risk, as they are small enough to potentially fall prey to the snails, especially if the snails are hungry and there are no other food sources.

Food Availability

• Sufficient Food: If there is plenty of food for both the shrimp and snails, they are less likely to interfere with each other. Assassin Snails usually hunt for other snails, not shrimp, but they will need an adequate food supply. You can feed shrimp supplemental food like algae wafers, blanched vegetables, or other shrimp-specific foods to ensure they aren’t competing with snails for resources.
• Snail Prey Availability: Assassin Snails thrive on small pest snails, so if you don't have a snail problem in the tank, they might turn to eating other detritus or biofilm, which could include shrimp larvae or very small shrimp.

Tank Setup

• Plenty of Hiding Spaces: Providing plenty of hiding spots in the tank is crucial for shrimp, as they often feel safer in places where they can retreat. If there are hiding spots like plants, rocks, or driftwood, the shrimp can easily avoid the snails if needed.
• Well-Planted Tanks: A well-planted tank with enough live plants will allow both shrimp and snails to have their own spaces. Plants also help to maintain a healthy environment, which benefits both species.

You can keep shrimp and Assassin Snails together as long as the shrimp much bigger than the assassin snails and the tank is well-maintained with plenty of hiding places and food for both species. Keep an eye on baby shrimp, as they are more vulnerable, and ensure there is enough food to prevent competition. If you are unsure or wanna be 100% safe, then it is best to avoid keeping them together.

Tank mates

Despite the scary name, Assassin snails can have tank mates. They can actually be kept with pretty much all community fish but it's important to choose them carefully.

Suitable Tankmates

Assassin snails are peaceful toward most non-snail tankmates. They do well with:

• Small community fish (e.g., tetras, rasboras, guppies, )
• Larger Shrimp (Big neocaridina, Vampire shrimp, Bamboo shrimp, etc)*
• Other peaceful and bigger snails (but avoid small or delicate species if you want them to survive)
• Bottom dwellers like corydoras or plecos.

Tankmates to Avoid:

• Other small snails (like ramshorns, pond snails, bladder snails, small nerites, or any other smaller snails) 
• Large aggressive fish (like cichlids or puffers) — they will harm or eat assassin snails.
• Goldfish — they can eat your assassin snails occasionally.
• Loaches — such as Clown loaches, Yoyo loaches, Zebra loaches, Skunk loaches, to name a few. They are known to eat snails.
• Delicate or very small shrimp species — assassin snails will pose a threat if they're hungry.

 

It is always very important to monitor behavior when keeping Assassin snails with shrimp, especially neocaridina or caridinas. Although it is relatively safe to keep bigger neos with Assassin snails, they can also be ganged up on the shrimp.

 

 

Assassin snail breeding and reproduction

Assassin Snails (Clea Helena) are fascinating creatures when it comes to breeding and reproduction. Here’s a rundown of what you need to know about their breeding habits:

Sexual Dimorphism

Assassin Snails have distinct sexes, meaning there are males and females. However, it's not easy to tell them apart just by looking at them. Males tend to be smaller and more elongated, while females are usually a bit larger and rounder, but this isn't always obvious. They are sexually monomorphic, meaning both sexes look the same externally. The only way to confirm a pair is to observe them mating.

Mating Behavior

• Courtship: Mating often involves a bit of "courtship" behavior, where snails engage in slow movements, touching each other with their tentacles and potentially rubbing their shells together. It’s usually not aggressive but can last for a few hours.
• Sperm Transfer: Snails have a specialized reproductive system, and the male will transfer sperm to the female during mating. The male extends his reproductive organ from the right side of his head, near the base of the tentacle, and inserts it into the female’s reproductive organ which is also on the right side near her head.

Egg-Laying

• Where the Eggs are Laid: After successful mating, the female will lay eggs in a safe, sheltered spot on hard surfaces in your aquarium, such as rocks, glass, or decorations. 
• Appearance of Eggs: Assassin snail (Clea helena) eggs are small, square to rectangular capsules, translucent to yellowish in color, around 1–2 mm in size, and always firmly attached to something. Usually laid one at a time, not in clusters. Inside each capsule, you'll see a single developing embryo. It may appear as a small dot or dark spot that slowly grows over several weeks.

Incubation

• Egg Development: Eggs typically take around 3-4 weeks to hatch, depending on the temperature of the water. Warmer water speeds up the process, while cooler temperatures may slow it down.

Hatching

• Baby Snails: Once the eggs hatch, you will see tiny baby snails that are fully formed and can move around right away. They are miniature versions of adult snails, but their shells are softer.
• Survival Rate: The baby snails are quite hardy and will usually survive well in most aquariums, as long as there’s enough food. 

Feeding and Care for Babies

• Feeding: Baby snails will eat detritus, algae, and leftover food. Ensure there's enough food for them to grow and thrive. You can supplement their diet with blanched vegetables (e.g., zucchini, spinach) and small amounts of protein (like frozen or live daphnia).
• Growth: The baby snails will gradually grow and start hunting small prey (like pest snails) once they are big enough. Within a few months, they will become sexually mature.

Population Control

• Overpopulation: They don't breed in large numbers like some other snail species so you will not need to worry about overpopulating.
• Space and Tank Conditions: Having enough space and the right tank conditions can help prevent overcrowding. If you don’t want them to breed, limiting the food source or adding only one sex (if you can tell the difference) can help control reproduction.

In summary, Assassin Snails are fairly low-maintenance breeders. Providing a stable environment with plenty of food and appropriate surfaces for egg-laying will encourage them to reproduce. Just keep in mind that they breed slowly and won’t overrun your tank as long as you monitor the conditions.

 

Health issues

Assassin snails (Clea helena) are generally hardy, but like all aquatic creatures, they can still suffer from certain health issues and diseases. Although snails are less prone to diseases compared to fish, they can be affected by environmental factors, poor water quality, and pathogens. Here’s a breakdown of potential health issues:

Poor Water Quality and Environmental Stress

Poor water quality is the leading cause of health problems in assassin snails. Issues like ammonia spikes, high nitrates, or low oxygen levels can cause stress and illness.

• Symptoms of poor water quality:

1. 1. Inactive behavior (snail becomes sluggish)
   2. Frequent hiding or burying in the substrate
   3. Shell damage or degradation (e.g., pitting or softening)
   4. Color fading or dullness in the body or shell

Regular water changes, stable water parameters (temperature, pH, hardness), and good filtration are essential.

Shell Rot (Bacterial Infection)

Shell rot, caused by bacterial infections, can lead to visible damage to the snail's shell, such as softening, discoloration, or holes.

• Symptoms:

1. 1. Soft, deformed areas on the shell
   2. Foul smell (due to infection)
   3. Snail may become more inactive or withdraw into its shell more frequently

Often linked to poor water quality, high levels of ammonia or nitrites, or physical trauma to the shell. Ensure high water quality, maintain stable conditions, and avoid sharp objects in the tank that could damage the shell. If an infection occurs, remove the affected snail from the tank and treat appropriately.

Snail Parasites

Though uncommon, snails can carry or become infected with external parasites, such as trematodes(flatworms) or gill flukes. These parasites may not affect the snails directly but can harm other tank inhabitants.

• Symptoms:

1. 1. White or discolored spots on the snail's body or shell
   2. Unusual movement or lethargy
   3. Visible worms or other parasites attached to the body

Typically, snails become infected when introduced to new tankmates or if water quality is poor. If possible, quarantine new snails before introducing them to the main tank. Treatment can involve using anti-parasitic medications designed for snails. Keep in mind that a lot of fish medications are very toxic to snails so choose carefully.

Death from Copper Poisoning

Copper is toxic to snails, and exposure to copper-based medications (like those used for treating fish diseases) or elevated copper levels in water can be fatal.

• Symptoms:

1. 1. Sluggishness or lethargy
   2. Snail may be seen floating or not moving
   3. Snail might retract completely into its shell and stop feeding

Copper poisoning usually occurs when medications containing copper are used without proper precautions or if the water has elevated copper levels from treated plumbing. Avoid using copper-based medications in a tank with snails, or if you must treat with copper, remove the snails first. Test water regularly for copper concentrations.

Infections Due to Physical Injury

Snails can suffer from infections if their shells are cracked, chipped, or otherwise damaged.

• Symptoms:

1. 1. Visible cracks or chips on the shell
   2. Soft or spongy areas on the shell
   3. Infection may appear as foul-smelling or discolored spots.

Cause: Physical trauma from sharp objects, fighting with other snails, or poor handling during tank maintenance.

Avoid rough handling or introducing sharp objects into the tank. Make sure the tank environment is free of sharp debris, and ensure snails aren’t being harassed by other tankmates.

Calcification Issues (Shell Deformities)

A lack of sufficient calcium in the water can lead to weak or deformed shells in snails.

• Symptoms:

1. 1. Soft or deformed shells (may look thin, pitted, or brittle)
   2. Snail may appear inactive or have difficulty moving

Cause: Calcium deficiency due to water that's too soft or lacks proper mineral content.

To correct this, add calcium supplements to the water (e.g., calcium-based aquarium supplements or crushed coral) and ensure the water hardness (GH) is in the appropriate range.

Overfeeding and Obesity

Overfeeding can lead to excess food in the tank, which can rot and degrade water quality, impacting the snails' health. Snails may also become overweight, especially if they don’t have enough natural prey (other snails) to hunt.

• Symptoms:

1. 1. Snail is overly sluggish or bloated
   2. Rotting food or uneaten debris in the tank
   3. Water quality may deteriorate rapidly

Cause: Overfeeding or not providing enough natural prey for the snails to hunt.

Feed snails sparingly, and remove any uneaten food after a couple of hours. Ensure they have enough snail prey (pest snails) or protein-rich foods to hunt.

General Prevention and Care Tips:

• Maintain water quality: Regular water changes, good filtration, and proper water testing help prevent many common issues.
• Feed appropriately: Ensure a balanced diet of snail prey (pest snails) and supplement with protein-rich foods.
• Monitor tankmates: Avoid aggressive fish that may harass snails and create physical damage.
• Handle snails gently: When cleaning or moving snails, always be careful not to damage their shells.

By ensuring proper water quality and environmental conditions, by providing appropriate care and diet, you can prevent most health issues in your assassin snails and help them thrive in your aquarium.

 

 

Toxic chemicals/medications

There are several chemicals and medications that can be toxic to aquatic snails, including assassin snails (Clea helena), and other invertebrates in your aquarium. Here's a list of substances to be aware of:

1. Copper-based Medications:

• Copper is commonly found in many anti-parasitic medications and medications for treating external infections(like ich or fin rot).
• Copper is extremely toxic to snails, even at low concentrations, as it interferes with their ability to properly process nutrients and can lead to death.
• Medications containing copper include:
• Copper sulfate (often used in snail eradication products)
• Copper-based treatments for fish diseases
• Tip: If you need to use copper-based medications, it’s best to remove the snails from the tank during treatment.

2. Formaldehyde:

• Formaldehyde is sometimes used in medications for treating external parasites like skin flukesor fungal infections. It is highly toxic to snails and other invertebrates.

3. Malachite Green:

• A fungicide and antimicrobial agent used in some treatments for protozoan infections like Ich.
• Malachite green is toxic to snails and can cause harm to invertebrates even at lower concentrations.

4. Antibiotics:

• While antibiotics are important for treating bacterial infections in fish, they can often harm snails and other invertebrates. Common examples include:
• Tetracycline
• Erythromycin
• These can disrupt the balance of beneficial bacteria in the tank and affect the snails.

5. Pesticides and Insecticides:

• Pesticides or insecticides used outside the aquarium can accidentally enter the water if contaminated, which is dangerous for snails.
• Even trace amounts of household chemicals like pesticide residues can harm or kill snails.

6. High Ammonia or Nitrite Levels:

• Ammonia and nitrite are highly toxic to aquatic life, including snails.
• Elevated levels can cause stress, damage to gills, and eventually death, even at moderate concentrations.

7. Chlorine and Chloramine:

• These chemicals are commonly found in tap water and are harmful to all aquatic organisms, including snails.
• Always use a water conditioner to neutralize chlorine or chloramine before adding new water to the tank.

Precautionary Tips:

• Read Labels: Always check labels when using medications in your tank, and look for any mention of invertebrate safety.
• Use Treatments Carefully: If you must treat the aquarium, try to remove snails before applying chemicals, and carefully follow the recommended dosages.
• Water Quality: Maintain excellent water quality with proper filtration and regular water changes to prevent harmful buildup of toxins or waste.

By being mindful of these chemicals, you can help protect your assassin snails and other invertebrates from harm.

What to look for when purchasing your assassin snails in store vs online

When purchasing Assassin Snails (Clea helena) from a physical store, it's important to ensure you're getting healthy individuals that will thrive in your aquarium. Here is what you should look for:

1. Shell Condition

• Look for intact, uncracked, and unbroken shells with a bright yellow and dark brown/black striped pattern.
• Avoid snails with erosion, pitting, or holes in the shell, especially near the apex (tip).

 

2. Activity and Movement

• Healthy assassin snails are often partially buried in the substrate or slowly moving across the glass or substrate.
• Gently nudge a snail—if it retracts or closes its operculum (the little trapdoor), it’s likely alive and healthy.
• Avoid snails that are floating, lying upside down for long periods, or emit a foul odor when removed (signs of death).

 

3. Size

• Juveniles are small and may be more fragile. Select bigger ones which are around the 3/4” to 1” mark.
• Buying mid-sized to adult snails gives a better idea of health and sexing (though sexing is extremely difficult externally).

 

4. Tank Conditions

• Ask the store about their tank conditions. Temperature, ph, hardness, etc, should be within the species' tolerance.
• Check that they are not kept with aggressive fish or in dirty tanks—this can stress or injure them.

When purchasing online, make sure to always select a reputable seller to buy from and inspect the snails upon arrival. Keep in mind that most assassin snails will arrive tucked in the shell and closed up. Acclimation and time is necessary for them to adjust to the environment so then they can come out to explore.

 

 

If you would like to purchase our Assassin snails, click here.

 

Leave us a comment below if this guide was able to help you. If you think there is any information we missed, please comment below and we’ll be happy to update the blog with more, helpful information.