From: gdrew@cs.umd.edu (Greg Drew)
Newsgroups: rec.aquaria
Subject: Re: Dead Guppys
Date: 24 Jul 92 00:10:34 GMT
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742

In article <711623833.21104@minster.york.ac.uk> sharon@minster.york.ac.uk writes:
>Last friday I bought my first fish, I bought 12 to start off with
>2 male guppys/2 female guppys/2 pearl guarmies/6 glo-ight tetras, they seemed
>[stuff deleted]
>had they been fighting between themselves and fought to the death ?
I doubt that your problem was the fish killing each other.  You are most 
likely experiencing "new tank syndrome".

An established aquarium plays host to two important kinds of bacteria, 
Nitrosomonas and Nitrobacter, which convert fish waste (ammonia) into a
relatively harmless compound called nitrate.  The process works in stages.
First, Nitrosomonas converts the toxic ammonia excreted by fish into nitrite,
which is even more toxic.  Next, the Nitrobacter convert the nitrite into 
nitrate, which you then remove with regular weekly water changes (change out
about 10% - 20% of the water each time).  A new tank has neither species of
bacteria present in any great numbers, so the tank has to "cycle" before it
can support many fish.  The cycling is started usually by adding one or two
hardy fish (assuming you have a 10 - 30gallon tank).  The fish produce ammonia
immediatly, causing the levels of this chemical to rise.  As it rises, it 
provides food for the Nitrosomonas, and the population of those bacteria rise
until they can consume all of the ammonia.  As the Nitorsomonas produce nitrite,
the levels of this chemical also build up, feeding the Nitrobacter.  As a 
result, you get 2 "spikes" (one ammonia, and one nitrite) before the bacteria
settle in.  If there are too many fish added at once, the spikes can get so
large that the levels of ammonia or nitrite can poision the fish.  That is 
probably what happened in your case.

To relieve this problem, you can do several things.  The most important is to
remove the poisions with frequent water changes (say every day or every other
day) until things settle out.  I would change out about 20% of the water 
each time.  Second, to halp lower the ammonia levels, most pet shops will sell
a little "pillow" of stuff that absorbs ammonia.  You can also reduce the 
number of fish.  It usually takes about 5 or 6 weeks for a new tank to be
ready.

All of this is based on the assumption that you have a filter which will help
support colonies of these bacteria as well as filtering the gunk out of the
water.  Aquaclear makes good filters.  The sponge they use will support 
large quantities of these bacteria (rinse the sponge occaisionally in the 
water you are changing out of the aquarium).  You can also use a corner filter,
a sponge filter, or any number of others.  A filter also circulates the tank
water, keeping the oxygen levels high.  If you do not have one, get one.

The very best think you can do for yourself and your fishes is to get a good
basic aquarium book.  I personally recommend (and have used) "You and your 
Aquarium", by Dick Mills.  "A Fishkeepers Guide to the Tropical Aquarium"
also by Mills (published by Tetra Press) is another good source.  You can
also read the FAQ for this group - I don't remember the ftp site offhand.
I hope all this helps.  Good luck.
					-- GDD
PS, don't give them so much food that lots of it does not get eaten.  This will
decay and make things worse.
-- 
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Greg Drew                          | Watch for coming attractions 
gdrew@trellis.cs.umd.edu           |
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Newsgroups: rec.aquaria