who is most susceptible to getting Ich???

[Magnum Man]

I always worry most about my cooler tanks, as the fish would suffer most, from heat treatment ( my preferred method )... however in the couple years I've had my tanks going again, I've had it in 2 tanks, both outbreaks, at "tropical" temperature's... so either I was just lucky, or maybe the parasite, doesn't flourish, at the cooler temps, & obviously they don't like the hotter water, as that seems an effective method to kill them off..., so maybe they thrive best at the same temperatures as most tropical fish do???

has anyone ever had Ich in a tank in the lower 70's degrees???

it appears as if cooler water does not stop Ich...

"This life cycle is highly dependent on water temperature, and the entire life cycle takes from approximately 7 days at 25 °C ( 77 degrees F. ) up to 8 weeks at 5-6 °C. ( 41 degrees F. )"

Ichthyophthirius multifiliis - Wikipedia

en.wikipedia.org

 

[Colin_T]

White spot can affect cold or warm water fishes but is more commonly seen on tropical fish like clown loaches. We also saw it on common livebearers (mollies, guppies, platies, swordtails), most tetras, some barbs and rasboras and sometimes on Corydoras. Clown loaches were the worst for it and every second batch would have it, whereas the other fish listed had it maybe once or twice a year. It always came from the suppliers getting fish out before they had finished treatment.

If cold water fish get it the parasite doesn't grow as fast due to the cooler water and you might see a couple of spots on a fish and a month later it might have a decent infection.

 

[GaryE]

How badly it affects fish depends more on their scale structure, from what I've seen. As Colin noted, it spreads more slowly cool, but it spreads.
You have to remember that as an organism, it isn't evolved to kill. I've seen several photos taken underwater in the wild where a fish might have one or two cysts. When they burst, the Ich is dispersed in a vast river, and most of them die without a new host. In a tank, they are caught between the glass walls and finding hosts at fatal levels is easy. It's not productive for them as parasites, because if all the hosts are dead, so are they.

I have seen heat resistant Ich - it makes sense that some strains would survive too short treatments and adapt.

My Microctenopoma, bushfish/African gouramis are Ich magnets. I have never seen this parasite on any of my killies, even when they were in with affected fish.

It's easy to treat with Malachite green, and harder to treat if you fear the meds. If you use proper quarantine, it will never get into communities or established populations. Even if it starts and spreads very slowly, a 3 week watch will let you spot it.