In 40 years of fish keeping I have never had a fish die that could in any way
be attributed to snails. Snails can be an intermediary host in a parasitic
disease that involves fish that eat snails but the snails have to be in contact
with birds and the parasite doesn't harm the fish and has to eaten by the bird
to carry on the disease other than that I know of no other disease carried by
snails for fish.

Moon
I breed dwarf crayfish for planted aquariums and grow trees in aquariums.
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