I always keep as many plants in a tank as I can. This seems to help with
the nitrates, but not with the nitrites.

I do this because I like plants and the fish like the plants.

I have bought fish from people that call themselves breeders and they have
completely empty tanks except for the fish. I couldn't ever do this.

Mind you, its pretty hard to catch fish in my tanks. It becomes quite a
game with many people involved everytime we want to catch something.
Invariably someone gets excited and destroys a plant or something just to
catch the fish.

Jim


NetMax wrote in message
.. .

"Jim Morcombe" wrote in message
...
Comments invited. Do I have this right?

I am "often" forced to have too many fish in a tank for a while.

When you add a heap of fish, the ammonia level increases. Most fish
are
quite tolerant of high levels of amonia, while others drop dead
quickly.

After a while, the additional ammonia provides nutrition for bacteria
that
convert amonia into nitrites. This causes these bacteria to flourish
and
for the levels of nitrites to increase.

Most fish drop dead at the appearance of nitrites. (Those that don't
are
the type of fish that are very cheap, just because they thrive in
anything).

When fish or plants die and are left in the tank, they decay and
produce
ammonia.

If fish die from Nitrite poisoning, then this means there are plenty of
bacteria present for converting ammonia into nitrites and not enough
bacteria that convert Nitrites into Nitrates. Hence the decaying fish
quickly add to the over-abundance of Nitrites, killing more fish.

As the Nitrite level grows, the amount of bacteria that converts
Nitrites
into Nitrates also grows. As it grows, the rate of conversion from
Nitrites
to Nitrates also increases. Unfortunately, most of the fish will be
dead
before the Nitrite to Nitrate conversion process can beging lowering
the
Nitrite levels.

All we can do to help is frequent water changes and remove dead fish.

Now, when you add extra fish for a dew days and then remove them, it
oftens
appears that you have escaped without upsetting your aquarium and
killing
fish. However, two weeks later, your remaining fish start to drop dead
at
an incredible rate.

This is because there has been a build up in the level of ammonia over
the
time the aquarium was over-stocked. This ammonia remains after the
excess
fish are removed. The bacteria to convert this into Nitrites slowly
begins
to flourish and to convert the ammonia into Nitrites. All of a sudden,
the
Nitrite levels reach the point of toxidity - well before the ammoinia
level
has dropped to normal - and death strikes.

The solution (other than not over-stocking) is:
1. severely underfeed the fish during the time they are over crowded.
This
means less fish poop and no leftover food to decompose. Hence the
increase
in Ammonia levels is kept to a minimum.
2. daily water changes while over stocked
3. continue water changes for two weeks after extra fish have been
removed.

Jim

I think you have this reasonably correct. There are also bacteria
seeding products, ammonia locking products and aquarium salt will help
fish deal with nitrites. I'd add that the amount of nitrifying bacteria
is directly functional to the amount of food being dropped in (the fish
are just a middleman, processing it to their waste products), so if you
double your fish load, but still feed the same amount, your nitrogen
chain is still very stable. Also the nitrites are being processed into
NO3 (nitrates). Beware that NO3 is a 'silent' killer. Fish exposed to
water shock of greater than 40ppm NO3 will exhibit varying degrees of
discomfort, and the smaller the fish, the more likely the shock will be
fatal, either directly, or indirectly through Ich or some other disease.
Nitrate shock is what kills new arrivals (when the rest of your fish are
fine). IME, death occurs on or before the 3rd day.

NetMax