Before I start, let me say that I’m not a 100% sure about all the facts but will share my thoughts. I understand that some snails are intermediate hosts for various parasites, especially internal parasites which I despise. I consider external fish issues as the lesser of two evils as I can see the problem and attempt to solve them. Whereas, internal parasites are often hidden and can cause massive damage before being caught. I recently had a bout with camanallus worms and it was a major pain.
That being said, I refuse to have any snails in any tanks that contain fish that are irreplaceable. For instance, I have a collection of exotic plecos and will not keep snails as I would rather not take the chance of them getting internal parasites. I do have snails in a separate tank with angelfish as I need to breed the snails to feed my puffer and don’t think twice about them.
I believe the snails need to first be infected through a carrier such as a rat or bird or whatever in order to be the intermediary. However, I don’t understand the process well enough so regardless, I just don’t take chances with snails in certain tanks for biosecurity. Again, im far from knowledgeable on this but wanted to share my thoughts since you asked the question. I’m sure
RD.
or someone with more knowledge can bring some clarity.