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Re: APD V4 #300 - Continued Icky Discussion

Date: Mon, 22 May 2000 21:41:48 -0500
From: "Klockers, Walter"

> I took it for granted that most, if not all, the people involved in
> this thread would know that the free swimming stage is that
> is being discussed here, but thanks for the review. <g>

First off, if I seemed to zero in on any one particular person - well, such
was just not the case. I was surprised at the *range* of responses coming in
and how far off base some of them were, but didn't want to be so specific as
to seem to choose only one or two.

One item I have learned over almost a decade of internet - when dealing with
a group, never assume anything...

> ...is there a *point* of temperature that the free swimming
> parasite cannot tolerate -- not merely reproduce faster and
> starving to death without a host? I guess you're saying "no"
> here. This also goes for the osmotic differences...at what
> point...? I've never seen such in the literature I've read.

Basically, the host and parasite must endure the same shared environment, so
both seem to have an equal tolerance for extremes within the same.

Raising the temperature alone, in the hopes of creating a shorter window for
the intermediate stage, works best when the outbreak is in its initial
stages and the parasitic population is fairly low (relatively speaking). If
it's reached the point of being widespread throughout the tank's population
then the sheer size of the parasitic population would throw the outcome in
favor of the wrong body. At this point, definite steps would have to be
taken to ensure the *fish* could survive the prolonged elevation. And at
some point, the hardiness of the fish starts to decline and stress factors
leave the immune system weakened, leaving you in a worsened position.

If I were to depend on osmotic differences it would be through the use of a
*salt dip*. Of course, this has absolutely no value as a weapon against the
free-swimming stage - it is only moderately effective against some of the
semi-exposed entrenched parasites at or fairly close to their "release
point". The idea here is to transfer the affected fish to a "cleaner"
environment, such as a hospital tank, with a much lower exposure incidence
while transferring as few parasites as possible with it. I'll touch on that
more in a minute.

> You mentioned 48 hours as to the time limit that free swimmers
> may need to acquire a host under "average" conditions. Baensch,
> v.1. states that "the cyst can divide into as many as 1,000 zoospores
> which have 70 hours to find a host"...At 90F or slightly above, I
> wonder what that "window" is?

The biggest reason I used the quoted phrase "average" is that I haven't been
able to actually pinpoint the temps involved in most of the relevant
studies. Some were interested in cold-water species, some were done with
Tropical Ornamentals in mind, an so on.

But the "1000 zoospore" figure seems relatively agreed-upon in all cases.

> I do remember reading some *speculation* about light and it's
> possible role in the stages of the parasite. That was prior to 1983.
> It made for interesting reading, but I can't remember anything more
> about it, including what publication it was in.

The reference to light in my case was aimed toward those who confuse the
treatment of freshwater Ich with that of the marine varieties. In other
words, those that report having "killed off" Ich by covering the tank and
throwing it into complete darkness are simply the victims of "post hoc"
reasoning and the timing of an isolated incident.

At this point, there's still speculation as to the effectiveness of the
treatment even in marine varieties...

> I've never kept the fish you've mentioned, so I certainly can't
> comment on them. However, I don't believe everything I read. <g>

Welcome to the ranks of the "Thinking Man". One should never accept anything
at "face value" without weighing the supporting evidence. Even the weight of
public opinion can't hold a real truth down...

> A concern of mine is that I have an emotional and financial
> investment in my 8 - 4"+ Botia sidthimunki. I would certainly
> hesitate to use Malachite Green on any Botia that has ich,
> especially having personally experienced what it can do to
> B. macracanthus, even at 1/2 strength.

Ah, now we're back to the "dip and slip" method.

Most of the remedies outlined in publications within our trade focus on
treating the community tank - the biggest piece of the aquarium pie and the
most likely to be in a hobbyist's home. Sometimes mention is made of
particular species or a genus that is intolerant, but most don't go beyond
that. What do you do with those few you have to watch out for?

Those unfortunates are rarely detailed because it involves a lot more work
than the community as a whole. And we all know how much the "average"
aquarist hates to associate the hobby with *any* form of manual labor or
effort. (Can you believe that Tetra has a new product on the market,
advertising its ability to reduce water changes to *twice annually*?!?!?)

We've all heard that Ich is as common to fish as the Cold is to humans, and
that the key to control is the vigorous health of the involved fish. If the
fish is already infected, then the most likely culprit is environmental
conditions - poor water quality, overcrowding, the wrong temperature, fright
stress, etc., etc.. Or in the case of a tank outbreak, as when brought in by
an "infected" fish, the sudden introduction of large numbers of the
pathogen. So we've got to re-establish an environment that will allow the
fish to regain its strength and fight off the infection naturally. Enter the
hospital tank...

By removing the sensitive fish to a clean hospital tank, you are removing
them from that overwhelming invasion of pathogens. There should be *NO* free
swimmers floating around, so the only thing you have to worry about is what
you bring with the fish. Hence the salt dip while transferring the fish.
From that point, make sure the environment of the hospital tank is as
optimal as possible for the fish's recovery while doing things like
increasing the circulation and elevating the temperature slightly to make it
harder for any freshly-produced free swimmers to find a host. Quite simply,
you have to reduce the pathogen population to a controllable level and hope
the fish can overcome it.

The "home" tank, whether empty (because the fish are in quaratine) or a
remaining community of hardier fish, can then be treated with normal
"antiseptic" routines so as to remove the scourge for the eventual return of
all of the fish.

> ...I'm quite curious about all this, and the books simply do not
> go far enough. I still have questions, and I guess the only way
> I can have them answered is to check at the university level. I've
> learned that the U. of Georgia has a good web site on ich, and
> I've emailed them with some questions.

A good place to start - the University of Georgia's Vet School is where most
vets and aquaculturists learn the art of dealing with sick fish...


David A. Youngker
nestor10 at mindspring_com