Snails in Pleco Tanks

[Redrain]

I've noticed a bunch of pond snails in my pleco tank which houses a few ancistrus, L226's and a Rineloricaria. I don't mind the snails much but would they be a concern to the fish since snails are a common vector for parasites? I haven't introduced any fish or plant in that tank for a very long time so they might have gotten in by a used net or water drops. The weird thing is I don't have snails anywhere else I'm not quite sure how they got there.

Anyhow, is their presence: Good/Neutral/Bad?
Thanks

[Bas Pels]

When the snails are placed into the tank, they can pose a risk of carrying a desease. In this case the snails are in the tank, and nobody is ill. I would not fear any risk.

[Redrain]

Now I think about it I remember throwing in some floating plants that might brought the snails with them.