Hirudo medicinalis, keeping the medicinal leech at home.

As with most animals I've always thought of the medicinal leech Hirudo medicinalis as pretty cool and after working a bit with them at ZSL I wanted to try them at home, here's how I got on. 

Housing is easy as long as its escape proof, sounds obvious but they really can get out of a tiny gap. I've used a plastic tank with a muslin mesh top under the lid until I found they could bite through the muslin when excited. Now if using a plastic tank (R.U.B, Ferplast, Hagen etc) I'd use a stronger mesh such as a pillow case and then put the lid on over the top to hold it. I'd then place the whole set up in the bath (with the plug in) for a while so you can see if any can get out and catch them if they do.
I now keep them in a custom made aquarium approximately 60 x 60 x 15cm (L x H x W) with plastic mesh (from a pound shop colander) glued over the vents. Water level varies between 15 and 50 cm.

Leeches in temporary tub for feeding, placed in the bath so if they escape I can see them. If left unattended for anytime I would add damp towels for hiding places to lessen the chance of them climbing out. 

(Note the plug is always put in).

Heating; Kept in the coolest room in my flat which is the toilet, winter night time temps can go down to around 10oC but often a few degrees higher. Although never really cold it will lessen the times I need to feed in the winter. If kept cool they need to warm up a bit to feed which they can do quickly but then if too cold there's a chance they will regurgitate their meal over the following days (but if cold there is less likelihood of them biting each other after feeding.)

Water changes,
I keep them in "matured" London tap water, normally by dripping in water from a nearby fishtank. Although the water isn't clean it is mature and near the same temperature as in the same room. I often fill it higher then drain down later that day or the next to help dilute any remaining waste. There is a small internal filter to help with water quality, at first they showed a lot of interest in this but within a day or so seem to ignore it unless other disturbances are happening. On may sites it mentions they can live in dirty water a while, I haven't measured any parameters but doubt they appreciate it so try and avoid it. After feeding I will do a small slow change daily to lessen the chances of an NH3 build up.

One supplier mentions using reverse osmosis water and adding their brand of water conditioners, this sounds a good idea. If using r/o I'm sure just adding 10% of tap would do (or a small amount of sodium bicarbonate?) I use normal London tap-water, as mentioned from another tank or having been left to stand overnight.

Feeding; This is obviously the biggest draw and drawback of keeping them, a few sites mention offering bloodworms, earthworms and bits of liver to them. None of these will be accepted by Hirudo but may be eaten by some smaller pond species (although if the liver was fresh from a still warm body they may latch on, and possibly wash it down with a nice Chianti?)
Another site mentions putting them onto your pet cat, I'm not going to bother discussing that one.

And of course there's the option of feeding them on yourself. 
That sounded cool when I was younger, now it sounds like a pain in the arse (soo to speak). A wound that takes ages to stop bleeding, the possibility of a reaction from the saliva and the possibility of an infection all make me think nope. Going to A+E because of any silly shenanigans is always something I like to avoid as they are busy enough without having to deal with my escapades.
If you plan on doing it I would suggest keeping the tank super clean and add a u/v filter to the set up if possible. I'd suggest don't share leeches and just to be extra careful don't use leeches from the tank someone else's leech has been put into. Possibly overkill? I don't know but why take the risk for a pet.
Some sites don't say about feeding them, just keep in a jar looking cool until they die then replace. Although they are “just a worm” I cant think this is a good way to look at something in your care. Hirudotherapy practitioners don't normally keep their leeches any length of time, they order in as close to the appointment as possibly, let them feed then dispatch them humanly.

Feeding that will work;
Getting fresh blood from a butchers is very hard as the animals they sell have been bled out at the abattoir, anything you see in the trays of meat is myoglobin and is possibly no use (see below). I contacted a few abattoir (all halal as the only ones I could see near London) about blood and one said yes but seemed hesitant when I asked about if its clear of anthelmintic (anti worm treatments for parasites in cattle etc). I'm sure all livestock has to have a period of time between slaughter and last treatment but couldn't find it. In future I think I will just buy and keep my fingers crossed...

Frozen blood; Again not easy to source, I found a company in Germany that sells it (Nov 2019) and brought the minimum amount to ship and keep frozen, that's 5kg, a lot of blood to store.
This has worked really well soo far however I'm not sure of the legislation of importing now we have left the E.U and the company hasn't replied to my request, (possibly as they don't know either) but this amount should last me most of the year. They say you can defrost it a bit then refreeze the rest, I don't think this is good so I have cut up the plastic bottles into chunks so I can defrost a portion as needed.

Do not do this when the neighbours are about!

I use dried sausage skins (again ebay) which you need to soak for a while to remove the salt preservative. I then pour the blood in, tie the top then leave to soak in warm water before offering it to them. You can use forceps to move the leeches to the food or put the sausage near the leeches and any hungry animals should latch on. Make up two or three sausages to use if there are more than one leech so you can attract them separately if needed.

One paper I read says the best temperature is around 24oC for feeding but cooler temperatures are preferred after a meal.
I normally defrost the blood slowly in the fridge, pour into the sausage skin then soak in warmer water till around 24oC, if they latch on but let go without feeding it seems the blood may cool too much and they dont then go for it. This seems surprising as it doesn't cool that quickly so it may be because of something else. One option is to put the tray into a heated tank but that adds another layer of hassle to what is basically keeping a worm.
I have seen them fed using petri dishes, either just placed into them when filled with blood or with a membrane stretched over (sorry I can't remember what that was, possibly sausage skin?) I have just ordered some 100% dried blood off ebay (sold to make blood pudding) so will try out all of the above soon and update!
After feeding, any animals that haven't fed may latch onto others and bite them. This can kill the specimen straight away or often gives the wounds on the body which see to cause constrictions making it hard for the to shed their skin in the future. Although it doesn't always happen it's worth separating feeders and non feeders for at least a few days. Here's a clip of a time I didn't do it. First you can see one biting another, then where I've separating them and the indentations on the bitten ones body. Lastly a vw of the tank the next morning as the animal has either vomited or bled out some of its meal.

Backstory;

When I started at the BUGS exhibit at ZSL the Hirudo medicinalis exhibit was at first a source of wonder but soon seemed rather dull.
The problem (as I saw it) is the exhibit is kept cold to lessen the need to feed the animals thereby making less work for staff while maintaining animal welfare and I do think the cool conditions made a duller exhibit as seeing live, especially large leeches either swimming or doing their swaying in the current as they search for food is pretty cool, leeches kept cold (or well fed) don't do this very much. If the tank is disturbed they will become active but in a zoo setting the frequent tapping on the glass tends to stop them responding unless its by a keeper doing maintenance.

I can only really remember a few feeding events from when I was there as I wasn't their primary keeper; blood would turn up and they would get fed, at one point we were having issues getting fresh blood and one of the vets gave a sample of his own to feed them. This was such a palaver due to the potential safety risks it wasn't repeated. After this we were supplied with blood from culled animals from Whipsnade, there mara and wallaby run wild and sometimes their numbers need to be kept in check.

At home in Grant Towers I thought about trying this species so trawled the internet for info, there are a few sellers offering only to hirudotherapy practitioners and a few that sold to anyone. I went with one that sold to anyone but could find little in the way of realistic husbandy info.
The leeches were sent from the EU and arrived in a zip lock bag in a padded envelope, so basically the soft body of the animal had minimal protection on its journey. Although they did seem fine I won't buy from them again.
I then looked at the sources of blood I had found. I asked at a butchers (trendy organic place in a good part of town) if they sold blood, the answer was no but they could collect some off a joint for me. This they did and I offered it in a sausage skin that I'd scraped the meat out of and also in a condom. They ignored the skin but the condom was too tough to bite through.

Using a condom to feed them but they couldn't bite through it.

Second attempt using sausage skins, this was successfully but all were dead the next day.

I then tried a few days later with sausage skin I brought dried and some fresh “blood”and they all fed straight away. However all the leeches were dead by the next day, at first I thought because of a anthelmintic (wormer) but it's possby because the blood wasn't “blood” but myoglobin , a protein found in muscles and is possibly not digestible to them. I sort of want to try this again to see the result, but am not going to because it means going and getting the myoglobin then all the set up to feed and it just may mean a dead leech. So it may confirm my theory, but as I'm not reliant on that source I will leave it for now. 

I then ordered more leeches from a website offering them for sale as fishing bait (they also sell to hirudopractitioners and vets) and I was informed that the animals are all of the same quality and kept the same and the only difference is the fishing specimens haven't been starved for 6 months as ones for medical purposes would be. I brought 6 and all fed straight away on the defrosted blood (lost 1 from being bitten and another just died). All have now fed a few times so I believe the use of the frozen blood and sausage skins is working, 

Leech information online;

I have found surprisingly little of use to someone that wants to keep them well and doesn't want to feed them on themself. There are a number of places you can buy them from but all the ones I've seen seem to expect you to either use for hirudotherapy and then dispatch them straight after or appear to be people who just want to make a YouTube video showing them with their cool pet but with little info I could use. 

Here are a couple of sites I recommend.

The person I am most in debt to is Nicolas from Cafarnarium who gave me lots of information, even though I havent brought anything! This I really hope to change as his list of species is amazing!

Biopharm in Wales are the main supplier I think of most the Hirudo for sale. Although they can't sell for pets (so don't ask) the specimens available as fishing bait (yuk) are the same quality they just haven't been starved yet so cant be used for hirudology. 

Pets-rawfood.co.uk is the company I brought the frozen blood from, they are not based in the UK so you need to buy a LOT to keep it frozen in transit.