I'm not sure that it is ALL bacterial, but the fin rot and bloody
patches certainly indicate bacterial activity. I read your later posts
also... The gold spots and dusty patches that you mention do sound like
Velvet (I have never had it in a tank but I have had White Spot once and I
do not want it again; all I know about Velvet is what I read online about
it). Bacteria are always present, and if a fish is weakened by a parasitic
invasion, the bacteria will use the opportunity to also invade. Most all
"pests" as such are opportunistic in this way. This is why the best defense
against such attacks is to do what you can to constantly keep the fishes
immune systems strong and keep the fish as healthy as possible. Plants
should only be purchased from tanks that do not have fish, and it sounds
like that was the case with yours, but perhaps they had been in contact with
infested fish or tanks at some point before you got them? I don't know, it's
just a thought... But once your tanks/fish have been healthy for a period
and nothing new has been added, there should be no Velvet or White Spot
parasites in your tank (or course there will always be bacteria). The only
way to be safe is to quarantine all new additions (fish and plants) for
longer than the parasites life cycle. Since I do not have a convenient way
to do that, my practice is to avoid introducing anything new into my tank,
no matter how much I'd like to. When I do have to for some reason, I'm
always worried about it. The one time when I did get White Spot (many years
ago) I had added two Plecostomus catfish. My tank is not planted anymore so
I don't have that to be concerned with. One thing you can do in the future
is to remove any sickly acting fish immediately to a hospital tank before
the bacteria can spread, and you can always expect a bacterial attack at
some point as the fish is stressed/weakened by parasites or other maladies.
The number of bacteria in the water has a direct relationship on whether the
fish can fight it off or not. Too many bacteria and they become overwhelmed.
It is also important to know and understand the life cycles of parasites and
to be able to identify them. A big part of my enjoyment of aquaria has been
in reading about fish diseases, parasites, anatomy, behavior and other
scientific and technical materials on web sites and it has also been handy
to know these things at times. I save web articles on my PC that I think may
be useful in the future, especially about diseases, in case I may encounter
any and have need to identify them and attempt to effect a cure. When you
think about the threats from bacteria and parasites, combined with keeping
fish in such small close-quartered environments as our tanks are, it is
almost asking for trouble, in some ways. One must be diligent and even then
things can happen.

Fedor



wrote in message
oups.com...
Thanks for the reply - i had not considered that it could all be
bacterial

I am going to remove the upside down catfish and treat elsewhere as it
is now the only sick fish left alive.
It now has a yellow dusting on its flanks as well as the spots - i am
at aloss really with so many different symptoms all at once.

By the way the zero nitrates is indeed a mistake, they are about
30ppm.

chris