Pond owners can remove leeches from ponds through regular cleanings to remove the sludge that attracts the leeches or by using a trap to remove leeches already present in the pond. When considering how to deal with leeches, knowledge of the different types of leeches and the difficulties posed by parasitic versus non-parasitic breeds is essential. The parasitic leeches are more likely to threaten the pond ecosystem.
The sludge that accumulates on the bottom of ponds is very hospitable to leeches and their breeding cycle. Individuals caring for rubber-lined ponds who want to proactively prevent leech breeding must clean the pond annually, ideally in early spring. After cleaning, a sludge-eating bacteria is introduced to slow the re-emergence of the sludge. Those caring for natural ponds with dirt or clay bottoms must clean the pond at least twice a year, in both fall and spring, to eliminate fallen leaves and branches that stimulate sludge growth. The sludge-eating bacteria must be added weekly.
To deal with an immediate infestation of leeches, a leech trap is helpful. These traps attract slugs into a can with a raw meat bait, trapping the leech. The traps must be checked regularly, replacing the bait and disposing of trapped leeches. The pond is clean when the trap ceases to catch new leeches.