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Comprehensive leech care guide: Updated as of 6/19/25

There's not a lot of public information on the domestic care of leeches outside of their medical uses and niche forums and facebook groups, so I wanted to create as comprehensive a guide as I can for proper leech care, referencing scientific papers whenever possible. This guide is open to corrections and input from other keepers and will be updated regularly as new information comes to light. If found in a reblog, always check to make sure you have the most updated version of this post. This guide pertains to the Hirudo verbana leech SPECIFICALLY but pulls from what information we know from Hirudo medicinalis due to their similar morphology and classification that only split in 2013. This guide will be operating under the assumption that bare minimums are not enough to thrive and has been written accordingly.

There are a lot of citations needed at the moment.

Tank specs

Size and Equipment Requirements

• For ideal leech care in display tanks, tanks should be at least 2 times the size of your leech tall, and have enough room to fit their body when stretched out at least 3 times length wise. This allows for swimming, the ability for leeches to escape each other, better water quality and the observation of various leech behaviors.

• 5-10 gallon fish tanks are great for a leech tank, with larger ones being good for groups. Bowls are suitable according to some keepers if your leech is solitary or small, but not recommended as studies have shown a tank without corners can stress fishes and aquatic life.

• Tanks should have dedicated land area in the form of exposed logs, cork bark, tank shelfs, etc. Preferably, these areas should have moss for leeches to deposit eggs. Tanks are able to be kept completely aquatic according to some keepers, but it is of my own personal opinion and is proven by researchers that this, and making your leeches breed late. can increase mortality in your leeches.

• Leeches thrive in low oxygen environments and typically produce very little waste, as such, tanks do not need a dedicated filter, especially if planted. If more oxygen is preferred, a bubbler on a low setting or high oxygen producing plants can be added. Large amounts of water movement should be avoided.

• Your tank must possess a tight lid of some kind as leeches will gladly squeeze through cracks to escape and explore. This lid can be a tight mesh, cheese cloth or some similarly breathable but secure fabric. This can be fastened with elastic to keep it secure over your tank or secured over a terrarium style snake lid.

Light Requirements

• Leeches should be kept out of direct sunlight and prefer dim or dark areas, though will still benefit from a regular light cycle.

Substrate

• Leeches require gravel/small rocks to dig through. Small lava rocks are highly recommended for their light weight and rough surface that encourages leech shed. In addition, lava rocks have shapes that provide large gaps for your leeches to hide in.

• Other substrates such as sand, soil, or clay balls may be added for planted tanks, and small clay balls work well to fill the bigger gaps between lava rocks if you don't want your leeches to burrow too far.

Plants and decor

• Plants are highly recommended for leeches, both as an area to breed, hide, and for general enrichment. Plants should be low light to match the light requirements of your leeches.

• An aquatic moss of some kind doesn't hurt for adding a little extra oxygen to the aquarium and acting as a hide. Prioritize mosses that have a lower temperature range, such as java moss, which is commonly cultivated, readily available, and is able to live in temperatures from 15-28⁰C.

• A land moss should be planted/attached to a surface above the water and maintained where your leeches can crawl onto it. This should be kept at varying levels of dampness for cocoon depositation. Please note that some mosses are illegally harvested, and you should do your best to get ones that have been cultivated instead. Sphagnum Moss is great for this purpose

• Anubias varieties of plants, good for their low light requirements and low maintenance needs, can add a visual interest to your tank.

• Leeches should have dedicated hides to provide a dark, safe place and reduce stress. Hides do not have to be large, and rough areas of the hides do not have the same concerns that exist with fish (ie. Fins getting caught), so are fine for your leeches. Thickly piled driftwood can provide great natural looking spaces for leeches to hide.

• Adding wood can be beneficial as it leeches helpful tanins into the water and can provide a land area for your leeches. If wood is collected from outside sources, it can be boiled for 1 hr to kill any outside bacteria or funguses. For wood gathered this way, it should be a hard, dry wood. Wood can be soaked in water for a few days before adding it to the tank to assist with sinking if desired.

• Cork bark makes a good floating platform, though it shouldn't be kept free floating to let the leeches get on easily. This cork bark can be used to hold mosses if properly supported.

• Plastic plants can be a welcome addition to provide places to hide or shed extra skin, but be cautious of sharp edges that may harm the soft bodies of your leeches. Plastic plants should be periodically taken out to clean to prevent algae build-up.

Water specs

• Leeches prefer colder waters and can survive in freezing temperatures. The survivable range of temperature to keep them at can range from 0-34⁰C (32-93⁰F) at the Absolute Extremes but ideally, your tank should be kept in the lower middle range of that 10-20°C (50-70°F) with only minimal or very gradual temperature changes. Leeches can survive being briefly frozen, but obviously, ideally will not be.

• Leeches should be in dechlorinated water, either through treating tap water, rain water, or spring water properly remineralized. Though pond water is suitable, the risk of adding parasites, unknown contaminates, or harmful bacteria means that it is not recommended.

• The total hardness of your water should be in the 50-100 ppm range to match freshwater sources. If your water has less, aquarium salts should be added to prevent the water from leeching minerals out of your leech.

• Distilled water should typically be avoided being used as-is as it's "dead" and all minerals have been removed. Distilled water can be made suitable by remineralization with appropriate leech salts.

Water changes

• Water changes should be performed roughly once a week, with the leech's low waste meaning that a planted, maintained tank may only need a water change monthly depending on water quality. You should be replacing about 20-30% of your water during water changes to remove dead skin and reduce the build-up of nitrates.

• Additional water changes should be done when leeches deficate after feeding, usually denoted by a brown or red tint to the water, and the water should be monitored for a few weeks after for ammonia spikes and changed as needed.

• During water changes, it can be helpful to take a moment to clean the glass of the tank, or to manually skim any excess protiens off the surface of the water if not in possession of a filter or skimmer. Snails can be added to your tank to reduce algae build up.

Number of leeches

• Leeches can be kept solitarily or in groups. As previously mentioned, a larger tank size is obviously recommended to show a full range of behaviors and allow for a more visually interesting experience.

• Though able to be kept solitary, leeches are best kept in groups of 3 or more, according to some keepers. Personal research to follow.

Leech behaviors and care:

Leech anatomy and lifespan

• Leeches are soft bodied worms, meaning their skin can be punctured by hard tools and caution should be used with damaging their bodies.

• Leeches possess 2 suckers, one posterior (Rear), and one anterior (mouth). These suckers are used to ambulate or latch onto surfaces.

• Leeches are hermaphroditic and possess both male and female sex organs that are only plainly visible during their mating season. Leeches can self fertilize.

• Leeches breathe through their skin like other worms, and this skin sheds off them periodically throughout the day by rubbing up against rough surfaces.

• Leeches possess small 'teeth' and separate jaws that leave a three pointed star mark behind when feeding.

• Leeches keep blood in their blood crop, where symbiotic bacteria keeps the blood fresh as they slowly digest.

• Hirudo Leeches have a lifespan of up to 8 years

Basics of leech behavior

• Leeches will remain at rest with their heads above the water, and will do so either folded in half or stretched out with both their suckers attached to the glass.

• Leeches love to hang out under the water when tank conditions are suitable, and will attach their posterior sucker to a surface, occasionally undulating to move water over their skin.

• Leeches will swim from one end of the tank to the other through anguilliform swimming similar to an eel but vertically.

• Sudden, dark shadows or changes in light can invoke a prey response in leeches and will cause them to hide until they feel safe.

•Leeches will often "sniff" the air or water around them.

• Leeches become overly active when hungry, showing an increased responsiveness to movement and shadow, and will swim to heat sources such as hands

• When feeding or reproducing, all of these normal behaviors halt in favor of the new ones, and leeches stop responding to stimulus at all, to the point that they could be cut in half and not stop their actions. (Though obviously, avoid actually cutting your leeches)

Reproduction

• Hirudo Leeches reach sexual maturity after about 1-2 years on average

• In the case of Hirudo leeches, mating season naturally takes place in summer, spanning June through August where your leeches female genitalia known as the clitellum will appear as a ring around the body, simalar to an earthworm.

• Breeding can be artifically induced by gradually warming up your tank, but is not reccomended so as not to stress your leech

• Mating takes place in the water, and while many keepers use a lack of land space as an effective form of egg deposition prevention, it should be noted that research shows that this is harmful and potentially deadly to your leech.

• Leeches will not show signs of pregnancy. Any lumps are sickness and you should refer to the proper section.

• Cocoons are commonly laid in damp land areas, either moss or soil in the wild, and take from 2 to 4 weeks to hatch as ~6 fully formed nymphs. (Conflicting information found. Citation TBA)

• Cocoons are soft when laid and proceed to harden over the next hour. Avoid puncturing or moving these cocoons while still soft.

• Termination of cocoons can be performed by freezing them and cutting them in half. Please note that freezing alone will not necessarily kill the eggs

• As previously mentioned, leeches can self fertilize, meaning you may have a cocoon even with one leech. Keepers should be prepared to terminate a cocoon in these cases.

• Unlike other leeches that die after mating, Hirudo leeches can reproduce for the duration of their lifespan.

Feeding

• Hirudo Verbana leeches feed once every 3-4 months with some suggesting more like 4-6. (Citation TBA) Feeding more often than this is likely to harm your leech by causing it to grow too quickly or cause it to vomit blood back up.

• The medically recommended way to feed your leeches is to get a sausage casing and fill it with animal blood (usually beef) warmed to body temp for your leeches to latch onto. This animal blood should be free of antibiotics and bloodthinners and can be collected from your local butcher.

• Please note that pig and raccoon blood should NOT be used, as they will kill your leech.

• Many leech owners will choose instead to feed off themselves for an easier, cheaper option. This comes with its own medical risks and care should be taken to avoid infection of the bite. You should ask your doctor before feeding your leeches off yourself. Once again, your blood should be free of antibiotics as they will kill your leeches.

⚠️ Note that sterile medical leeches kept in non-sterile environments like this will cease to be sterile

Now that I've legally covered my ass, assuming you are feeding off yourself, the following is important information to have.

◇ Materials: Antibacterial soap, isopropyl alcohol, sterile surgical pads (available cheaply at pharmacys), medical tape or masking tape if not available, liquid bandage (optional) and a pill bottle (optional)

◇ Skin should be cleaned before feeding to avoid risk of infection.

◇ Leeches should be fed on thinner skin, but avoid feeding directly over veins. Common bite locations for keepers are feet or the arm due to the thinner skin there.

◇ From personal experience, try to keep your leeches far enough away from each other that they can't touch the other's bite wound when they eventually fall off.

◇ To have your leech bite in a specific area, avoid veins, or encourage biting, your leech can be placed in an empty pill bottle and held to your desired bite location.

◇ Leeches will inject an anesthetic similar into the bloodstream, which may cause feelings of mild euphoria or lightheadedness, in addition to the injection of a powerful blood thinner. You should not self feed if you are on any combination of blood thinners. The bite will range from painless to feeling like a small prickling similar to a shot or gentle tattoo.

◇ Feeding takes up to an hour, and after feeding, your leeches will simply drop off of you. The blood thinners will mean that you will bleed constantly for up to ~10 hours afterwards.

◇ After your leech has fed, hold pressure to the location, move to the sink, and thoroughly clean your wound(s) with your antibacterial soap and alcohol before bandaging properly and applying pressure with a surgical pad and medical tape

◇ Liquid bandage on the wound will quickly stop the bleeding but has been reported by some to increase risk of infection. Risk of infection COULD possibly be lowered by letting yourself bleed to flush out bacteria from the wound for an hour or so, but this is a hypothesis and has not been proven.

◇ You should be prepared to bleed a LOT. Pads should be changed every 2 hours or when bled through to the point of being soaked.

• Baby leeches are often too small to penetrate skin and, in the wild, would bite through the thin skin of frogs. In captivity, baby leeches will feed off their parents or can be helped during self feeding by pricking with a sterile diabetic needle to help break the skin.

• NEVER try and pull a leech off your skin without first breaking suction. Doing so will cause the leech to possibly vomit up blood and bacteria into the wound, greatly increasing the risk of infection, or harm the leech itself.

•If your leech bites when you don't want it to and you Absolutely need to remove it, slide a nail under the anterior sucker to break suction. Note, though, that it's easy for this to harm hirudo leeches by damaging their skin and jaws. It should be avoided when possible.

⚠️Signs of Infection⚠️

If self-feeding, you must be EXTREMELY aware of what the signs of infection look like. These may include:

• Spreading Redness

• Swelling

• Excessive pain or itching sensation

• Wound feeling hot to the touch

• Discharge from wound such as puss

If you suspect at all that you may have an infection, IMMEDIATELY go to your closest urgent care to recieve medical care. If they ask you how you got it, specify that they are leech bites.

Handling of leeches

• Leeches should not be handled after feeding for at least 2 weeks as it can cause digestive issues.

• In order to not over stress your leech, keep handling to a minimum.

• Gloves recommended during handling to prevent accidental bites

On the care of sick leeches

• Leeches when sick will have a lumpy appearance to their body, often caused by an internal twisting of their blood crops. Inexperienced leech keepers will oftem mistake this for "pregnancy". This can sometimes be healed typically by adding extra tannins to the water via betta leaves or Adler pine cones. Your leech should NOT feed until all lumps are gone.

• It's possible if not given enough to rub against that your leech's shed may get stuck, giving them a pinched appearance. This can usually be solved by gently rubbing the leech between your fingers in the effective area until shed loosens.

• "Air taken in during a feed can be potentially life threatening. (C. Peters, pers. comm.) The leech should be held between finger and thumb, and both digits run along the length of the body, expressing as much air and blood meal from the animal as possible" (Spencer and Jones, 2007) Please note that this is outdated information and needs verification.

How to aquire leeches

⚠️Do not buy from leech.com!!!⚠️

We recommend you buy from reputable bio pharmas or leech breeders

Conservation

• Hirudo medicalis leech populations have declined in their natural habitat spanning across Europe and parts of Asia due to over harvesting of leeches for medical purposes in the 19th century, drainage of wetlands, and the reduction of horse use.

• Hirudo Medicalis leeches are currently considered near threatened in the wild and are protected from wild harvesting

• Most leeches for purchase will be Hirudo Verbana, a seperate species of medical leech from areas of the Mediterranean and turkey.

• Any leeches should be bought from a reputable breeder

• NEVER release your leeches into a non-native environment

Helpful Groups

(Please note that not all advice will align with the one given in this guide. I try to use the most recent scientific articles but this is still largely unstudied as a hobby)

r/Leeches on Reddit

Leech Gang on facebook

References

Spencer, W. & Jones, G. (2007): The captive breeding and educational display of the Medicinal Leech Hirudo medicinalis (Linnaeus 1758) at Bristol Zoo Gardens NOTE. OUTDADED AND NEEDS CORRECTION

TBA. So many TBA. Adding pics in the meantime until I cite the articles in mla

Search Engine Terms. Ignore if using guide

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You could say they're my flesh and blood