The young parasite creaps out into the mucous immediately after birth and can produce another youngster after only one day and then every four to five days. They live for about twelve to fifteen days at temperatures between 59 o F and 68 o F and are easily treatable. This fluke is not thought to be a serious or significant pathogen in properly controlled systems and are not a problem unless really heavy infestations are present. A long worm like creature with a membered body which has a sucking disc at both ends. Movement of this parasite is by means of looping like a caterpillar.
Leeches feed on blood and can also be bearers of blood parasites.
They lay there eggs in cocoons on the pond bottom, plants, stones, etc. The leech is not an obligatory parasite and may leave their host for long periods of time, as they can survive for prolonged periods without feeding. The greatest threat to the fish from the leech is caused by moving from fish to fish whilst sucking blood, with a great risk of spreading any virus diseases present to all the fish in the pond. Leeches are common in planted ponds and are less likely in non planted ponds. They can infect all parts of the fish including the mouth and gill areas, and this parasite is extremely difficult to eradicate.