New syndrome?

"NetMax" wrote in message
...
There is NTS (new tank syndrome) which is well known to almost everyone,
and there is OTS (old tank syndrome) which is known to most of the
regular readers here and experienced hobbyists, but I think I have a new
one for you to consider.

Have you heard of this scenario before? You introduce a seemingly
healthy fish to your tank (without quarantine, though I'm not certain how
effective quarantine would be in this case), and within a few days, all
the fish in the tank are dead (from bacteria and/or Ich). The common
denominator is that the hobbyist had not added anything to that tank for
a long time (over 8-9 months), and their fish were all healthy before.
This is a real heart-breaker, and to add insult, very often, the
introduced fish survives, seemingly oblivious to the carnage it has
caused.

Having heard of this occurrence from many other hobbyists (and
experienced it), I've a hypothesis which I'll call NGS (new germ
syndrome). I don't think it's as simple as the introduced fish being a
carrier. The problem is the prolonged inactivity of the immune systems
of fish which have been isolated for many months, preventing them from
reacting to the almost benign germs which are always present in normal
waterways. The human equivalent would be someone living in a sterile
bubble for a long time, who would be at a pneumonia risk from common cold
germs.

The problem is worse with fish, as they don't have an atmospheric shield
around them like humans. In nature, fish are all interconnected by
water, which is an easy conductor for parasites, bacteria etc. If one
fish is sick, they are all exposed to the same contagion, to varying
degrees of concentration, depending on their proximity to the greatest
source of the disease. Consequently, in nature, fish are always exposed
to disease, and the exposure typically ramps up (as the disease spreads).
This would require the fish (in nature) to have a very active immune
system in 2 regards. First, the constant exposure would require the
immune system to be constantly working. It would always be under some
attack, as diseases evolve to counter the fish's defences. Secondly,
since the attack is progressive, the health of the fish depends on the
immune system's ability to produce the correct defence for when/if the
disease concentrations become higher.

In an aquarium, with our relatively huge fish-loads, disease
concentrations ramp up faster than their immune systems can react. Also
the immune system's ability to defend against a particular contagion
depends on if it was ever exposed to that contagion before, so (in
theory) a variety of low-level exposures, successfully defended against
would produce the strongest immune system. However, by intent, aquarium
bio-topes do the opposite, reducing the attacking contagions to zero.

In an established tank, with no introductions for say, one year, you
might conclude that the inhabitant's immune systems are dormant from lack
of use. This might be ideal (as it indicates a contagion-sterile
environment), unless you want to add something (fish, plant, snail etc).
Then you have the worst case scenario, a new contagion, small
environment, and a bunch of immune-suppressed fish who will not even know
what hit them.

NGS, New Germ Syndrome

There are varying defences for this, but I thought I'd start by floating
the concept through the newsgroups for comment first. There probably
exists a more technical term for this (especially as applied to humans),
so if you know of one which applies to fish, please share it.

NetMax



NetMax,

Sounds reasonable to me. My wife and I have discussed many times a similiar
scenario with children. We have friends and family on both ends of the
scale. The scale being allowing one's kids to become exposed to any number
of things through the natural course of life, (playing the mud, eating
insects, contact with animals/other children etc.) thereby encouraging their
immune systems to be stronger. vs. Trying to bring your kids up in a
"vacumn" where everything is sterilised religiously and the kids are
prevented from coming into contact with diseases etc. such that when they
do, they fall ill easily and battle to overcome it. How many times have you
heard the story about how when a child first starts going to playschool,
within days or weeks they are sick and this continues for a few weeks until
their immune systems become stronger and they are able to cope with the bugs
they are coming into contact with. This is particularly evident where the
child is an only child and hasn't come into contact with many other kids,
prior to going to school. I digress......

It would seem to me that what you are talking about could also be worsened
by adopting too clinical an approach to tank maintenance. Recently there was
discussion in a post about how the soap on your hands could affect the fish
and the insinuation was that one shouldn't place your hands into the water
without being absolutely sure they are soap free. I don't disagree however
being too particular may actually be causing your fishes immune systems to
become "lazy." Similarly I have been given advise to have a seperate net for
each tank, in order to prevent the spread of disease from one tank to
another. Again I can see the logic in this, but on the other hand, unless
you are actually dealing with a disease, it would seem to me that the tiny
amount of pathogens which might be transferred by a net might actually
provide that "variety of low-level exposures" you mention.

We have all become familiar with the term immuno-suppression (sp?) which of
course is something slightly different, being a disease-like condition in
itself, but goes part-way to describe your new term "NGS." I did some
searching on Google and came up with the following article. It deal with
humans but the same must apply.

http://www.discoveryhealth.co.uk/gen...storyid=106923

Anyhow, just my thoughts!

Gordon