Can this cause ich?

Stress could contribute towards it.

I agree, stress is huge when any disease shows up. Especially ich. Female platties, swords, etc. with too many males are prone to getting it easily. Fish being picked on usually don't get enough food and their immune system deteriorates, leaving them prone for diseases. Plus if they're getting beat up, literally, they can lose their proctective mucas coat.

Good luck!!!

Short answer--no.

Ich has one, and only one, causative agent--a one celled, ciliated protozoan parasite Ichthyophthirius multifiliis.
If this organism is not present in your aquarium, your fish will not get infected with ich.

If the ich parasite exists in your tank, certain fish are more likely than others to show signs of infection than others. Silver dollars are high on the list of susceptible fish.

By the way, why are you keeping peaceful Metynnis species with a notorious bad acting cichlid?

Bill in WI

Agree w/RioXingu. But, if subclincal Ich is present in the tank, stress levels can favor an outbreak.

i've had ich in tanks isolated (nothing in) for years. I lost a heater for a week had a snowy outbreak for no other reason that temp stress IMHO
Silver dollars are not that docile remember they are close relitives to pirahnas At work we have a tank full of common silvers 30 red hooks 50 and a dosen asst large SA cichlids those SDs shred every new fish that go's in there.


BTW I learned that victoria and malcchide(sp?) green are allmost worthless in very hard water for ich treatments.
I would try copperformlin (sp?) for hard water or treating most silver fish.
If salt and temp didnt work BTW those SDs have no probs with 90F fry off that ich with a quickness.

I agree with RTR's additional comment.
The convict cichlid might have worked out with the silver dollars; I guess it was worth a try. There are a lot of individual differences in how these fish behave. Size plays a role too.

Bill in WI