Advise with Ich in cory tank.

[cichlid2006]

I was told that protozoa, viruses, parasites, etc., are always present in some form and exist in cycles, never completely eradicated. Only fish under stress or those with compromised immune systems will actually get sick. This is what someone with a PhD told me. I'm not the expert and was just passing along info that has always worked and proved accurate for me.

thats fair enough you only know what your told.
ich isnt always present in a tank, its an introduced parasite and it can be eradicated at certain stages of its life cycle. this is what the temp increase is for, to speed up its cycle so it hits the free swimming stage more often in a treatment cycle. this is the only time the protozoa is vulnerable at the doses safe to fish.
some bad bacteria and fungus are always present but they usually need an open wound or weakened immune system to take hold. ich is not a bacteria or fungus it is a parasite that has to be introduced.

fish generally get sick after being under stress and that is why ich takes hold often quickly after a fish has been introduced to a tank as the fish is stressed, even though there were no signs of it in the store.
i think your event with the rasbora was more lucky than through prudent measures.
if you read the link i gave the original poster then that will give you a good way to treat it.

here is another good link to give details about the parasite http://www.aquatic-hobbyist.com/profiles/disease/freshwater/ich.html

 

[novembergale]

Thanks, I guess I have been pretty lucky. I've never really had a major problem with ich affecting an entire tank so it must just be pure luck. I do change 50% of the water every week (25% mid-week and again on the weekend) so that may help too.

 

[cichlid2006]

Thanks, I guess I have been pretty lucky. I've never really had a major problem with ich affecting an entire tank so it must just be pure luck. I do change 50% of the water every week (25% mid-week and again on the weekend) so that may help too.

your obviously a good keeper if none of your other fish got infected because for that not to happen all your water perameters would have to be tip top. what you were told is one of the perfect examples of why you should do a little of your own research after being told something by someone, no matter how knowledgable or educated they are or seem to be.