Re: Ich

---------- Forwarded message ----------
To: Aquatic-Plants at ActWin_com
Subject: ich
Date: Wed, 31 Jul 1996 10:36:26 -0400
From: Thomas Narten <narten at raleigh_ibm.com>


I suspect it is nonsense that ich can't survive at 85-90
degrees. Raising the temp increases the metabolism of the critters,
which shortens the overall life cycle. The ich life cycle consists of
infection of the fish as well as a free-swimming phase.  That means
the parasite falls off the fish and has to reinfect it. "Curing" ich
means that fish have to get rid of the existing parasites and also
ward off reinfection from the next ich cycle.

Ich medicines kill ich in its free-swimming state (only). The
free-swimming stage is fairly short; if no new host is found, ich
dies. Thus, removing all fish from a ich-infested tank for 1-2 weeks
gets rid of the ich in the tank.  Again, ich medicines stop
reinfection, but do nothing for the infection itself. Reasonably
healthy fish can often ward off reinfection on their own. That of
course depends on how bad the infestation is, the state of the fish,
etc.  This accounts for the "raise the temp is all you need" cure.  No
medicine does anything to the ich that is on the fish -- its protected
by the fish's slime coating. So you have to wait for the fish's own
immune system to take care of the ich.

Thus, raising the tank temp often suffices. But high temps also stress
fish (and some plants). So there is no free lunch here. Note also, that
if you use medicine, use them a few days longer than "fish seem
OK". You want to get all the free-swimming critters, which you can't

It also appears to be the case that ich survives for extended periods
of time on fish in a cyst state. No apparent symptoms, then at the
onset of stress, the fish gets ick. Adding new fish to a tank often
triggers this. The new fish gets blamed, when in fact the ich was in
the tank to start with.