The Fate of my Leeches  10/10/11
First I wish to say greetings to you from both my husband and me. We have both looked for answers to our questions on WWM over the years.
<Thanks for your kind words.>
Here is some background information: I have a 16 gal bow-front tank which has been set up for a few years. It contains cherry shrimp, class N Endler's, Hara jerdoni, Scarlet Badis, Malaysian Trumpet snails, and Tanichthys micagemmae. This tank also is thickly planted with various Cryptocorynes, Bolbitis heudelotii, and Windelov java fern (the latter 2 attached to African Mopani Root Wood). For filtration I use an Eheim HOB filter. I also use an air pump with airstone to keep oxygen levels up at night due to all the plants. I recently added a moss ball. As everything else has been in the tank at least a year, I am guessing that this may have been the culprit.
<Perhaps. Moss Balls -- if you mean those Cladophora colonies -- are coldwater algae, and as such, may be cultivated outdoors or in ponds. As such, they may bring in all sorts of pond life. They don't do particularly well in tropical conditions, and without constant rolling around like they get in the wild, eventually fall apart into some sort of mat or lump.>
Last month, I noticed a light gray "worm" of about 3" length and perhaps 1/4 - 3/8" wide swimming like a snake in the tank when the lights first came on by timer. It rapidly headed for the substrate and buried itself.
When I feed in the mornings (but not in the evenings), I occasionally see a portion of this "worm" sticking out and attempting to catch bits of food.
<Sounds like a leech!>
I feed New Life Spectrum small fish formula 0.5mm size, Fluval Shrimp Granules, New Life Spectrum optimum freshwater flakes, and live Daphnia (species unknown -- local culture I have kept going indoors for a couple of years). I have never seen any type of worm in my Daphnia tank.
Last time I vacuumed the gravel, two of these "worms" were left in the bucket and were attached at both ends to the plastic bottom of the bucket.
This is what made me pretty sure I had leeches. I attempted to take a picture then, but as my camera is of poor quality, the results were nothing more than a gray blur.
<Oh.>
Now, here is the question: I find the leeches are pretty awesome. My fish all appear healthy and are eating well. My plants look fine. The shrimp are still reproducing. I actually enjoy watching these leeches move around in the tank (when I am lucky enough to see them swim) and I enjoy watching them try to catch bits of food. My husband is of the "EWW it's a leech!"
school and advises a full tear down of this tank to remove the offending leeches. We have 7 tanks total between us. This tank has its own gravel vac and siphon tubing and its own nets. We use one set of 5 gallon buckets for dirty water and 5 gallon drinking water containers for clean water. I don't see much chance of contaminating the other tanks with my leeches, but this is his worry. He is concerned that I will put leeches in our 125 gal Tropheus moorii Moliro Red/ Eretmodus cyanostictus Kapampa tank. My only real concern is for my Hara cat and my Badis. They both love to eat tiny live things and I am somewhat concerned that they could become ill from eating baby leeches.
<Most leeches are in fact free-living and feed on invertebrates. So things like bloodworms would definitely be on the menu! They may even scavenge to some degree. Some are blood-sucking on fish, but these tend to leave obvious wounds, often with a three-tooth bite distinctive to this group of animals.>
We have agreed that we will post this issue to WWM and proceed as directed.
Both of us respect your opinion on such matters.
Thank you,
Val
<Without a positive ID it's hard to be sure. If this was me, I'd perhaps experiment first. Put them in a breeding net, and see if they eat wet-frozen bloodworms or krill. If they do, and seem to be free-living rather than parasitic, doing well for a few weeks under such conditions, I'd then maybe try them out in a tank with fish too large to be damaged.
But I'd keep a very close eye open for odd bite marks. Hope this helps, Neale.>

Ftn. leeches?? 12/17/10
I have found small red worms that strongly resemble ones discussed on these two pages http://www.wetwebmedia.com/fwsubwebindex/tapewmfwf.htm
http://www.viaquaria.com/forum/showthread.php?1679-Callamanus-worms-%28red-worms-from-fish-s-anus%29-Problem-Solution
in a freshwater outdoor water fountain (with no fish). When I go to change the water every other day or so they float up and are swept out of the fountain and into the flowerbed. Birds use the fountain to drink and I imagine that mammals use it at night. I have red wriggler earthworms and décolleté snails in the yard also, but never find them in the water fountain.
My questions are;
Are they harmful to birds, cats or skunks etc?
<Can't tell with the information presented... All Leeches are parasitic...
can't/don't live long w/o hosts. Do yours show segmentation, suckers?>
If they are harmful how do I eliminate them?
<Simple bleach>
Is it possible to 'dose' the water to prevent their return?
<Depends on the source...>
I don't currently have a pet but when I did she did drink out of the fountain, when I get another will I have to prevent it from doing this?
<Doubtful>
Thanks, Pam Kelso
<Welcome. Bob Fenner>
Re: leeches?? 12/18/10
Thank you for the reply. In rummaging around the internet after I sent this to you I think that I have identified the culprits. They are midge fly larvae, bloodworms.
<Ahh! Quite common to have such insects w/ aquatic larval stages using water features opportunistically. And not a disease issue>
Because I clean out the fountain every few days I never saw them at maturity and they were always small and non-segmented. I know that we have midge flies so I think that solves it. Thank you for getting back to me so quickly.
Pam Kelso