Tetras behaviour

Hi all
I have had some Buenos Aires Tetras for about 9 months now. I originally
had 3 with 3 small cories. Then I read they preferred larger groups. So I
bought 3 more - fairly light load for a 29 gallon tank. For quite a while
everything seemed hunky dory. Frequently I would enjoy watching them
shoaling around typically behind the lead of one of the 3 larger fish.
After about 5 or 6 months I noticed them shoaling less, but still
occasionally, and instead seemingly becoming a bit territorial. The norm
became the dominant fish would stare out one end of the tank and run off
anyone who came into his half. This was quite frequent so I assumed to some
degree it was just playing. Another of the largest staked out an opposite
corner, with similar territorial behaviour - but just a small radius. One
of the remaining fish had a tendency to hangout below the filter output and
the remaining 3 would just kind of mill around, occasionally 'nipping' at
each other when they werent being chased, but not frequently. Then about
a month ago I found the largest one who didnt have an 'area', with a big
chunk out of his belly - obviously nibbled on considerably after an intial
attack?. This may have been the one who had taken to hiding in a decorative
trunk - I did not notice any physical problems till its death, though it
could have gone unnoticed. In the last couple of days I have discovered
the Tetra who was previously claiming one corner is now hiding in the trunk
and the top half of its tail fin is missing. So I am assuming the alpha
Tetra is slowly knocking off any challenge to its dominance, even though it
usually seems content staying in his half alone.
My questions-
Is this type of behaviour at all typical of Buenos Aires, particularly in
regards to going from communal to territorial?
Is there something I can do to alter the 'atmosphere'?
What do I do about the injured fish? It doesnt seem to be eating,
possibly partially because it is cowering/hiding and I suspect it is much
less mobile missing half its tailfin. Because I wasnt watching closely the
first one may have gone through the same scenerio - injury, cowering, death
then being eaten on. I could (reluctantly) move it but dont have any good
choice. I have two fancy goldfish tanks with some 'growing' room. I have a
15 gal tank which seems pretty happy with 3 neons, 3 yellow tetras and 3
gold skirts. And I have 2 10 gal guppy tanks pretty much 'full' -one with
adults and one with 'salable size' babies.
I used to love the Buenos Aires tank but it has become so unharmonious I
am tempted to trade them all in on something else - but still not sure what
to do with the injured one. With this pattern I may just end up with one
unhappy bully anyway.
Any suggestions would be appreciated.
Bill Brister

"humBill" wrote in message
...
Hi all
I have had some Buenos Aires Tetras for about 9 months now. I
originally had 3 with 3 small cories. Then I read they preferred larger
groups. So I bought 3 more - fairly light load for a 29 gallon tank.
For quite a while everything seemed hunky dory. Frequently I would
enjoy watching them shoaling around typically behind the lead of one of
the 3 larger fish. After about 5 or 6 months I noticed them shoaling
less, but still occasionally, and instead seemingly becoming a bit
territorial. The norm became the dominant fish would stare out one end
of the tank and run off anyone who came into his half. This was quite
frequent so I assumed to some degree it was just playing. Another of
the largest staked out an opposite corner, with similar territorial
behaviour - but just a small radius. One of the remaining fish had a
tendency to hangout below the filter output and the remaining 3 would
just kind of mill around, occasionally 'nipping' at each other when
they werent being chased, but not frequently. Then about a month ago
I found the largest one who didnt have an 'area', with a big chunk out
of his belly - obviously nibbled on considerably after an intial
attack?. This may have been the one who had taken to hiding in a
decorative trunk - I did not notice any physical problems till its
death, though it could have gone unnoticed. In the last couple of days
I have discovered the Tetra who was previously claiming one corner is
now hiding in the trunk and the top half of its tail fin is missing.
So I am assuming the alpha Tetra is slowly knocking off any challenge
to its dominance, even though it usually seems content staying in his
half alone.
My questions-
Is this type of behaviour at all typical of Buenos Aires,
particularly in regards to going from communal to territorial?

It is not that unsual, given the right circumstances, and can occur with
other tetras as well, though the Buenos Aires tetra is a more aggressive
tetra to start with.

Is there something I can do to alter the 'atmosphere'?

Yes, the fish are concentrating on each other because they can. You need
to provide more representative distractions as they would experience in
nature. This includes removing or adding some Buenos Aires tetras,
adding larger fish (semi-predatorial) or pack fish (group of barbs) and
at the same time re-arranging the interior of the tank (add/remove
rocks/driftwood etc, move plants around etc). A tetra's territorial
instinct is relatively loose, so reseting the behavior is relatively easy
(the exception, if there is one, is a larger and well established alpha
male).

What do I do about the injured fish? It doesnt seem to be eating,
possibly partially because it is cowering/hiding and I suspect it is
much less mobile missing half its tailfin. Because I wasnt watching
closely the first one may have gone through the same scenerio - injury,
cowering, death then being eaten on. I could (reluctantly) move it but
dont have any good choice. I have two fancy goldfish tanks with some
'growing' room. I have a 15 gal tank which seems pretty happy with 3
neons, 3 yellow tetras and 3 gold skirts. And I have 2 10 gal guppy
tanks pretty much 'full' -one with adults and one with 'salable size'
babies.

It depends on the extent of the damage.

I used to love the Buenos Aires tank but it has become so
unharmonious I am tempted to trade them all in on something else - but
still not sure what to do with the injured one. With this pattern I
may just end up with one unhappy bully anyway.

This is a scenario which many cichlid owners regularly face, especially
with mbuna, as territories are carved out. The same solutions loosely
apply.
--
www.NetMax.tk

Any suggestions would be appreciated.
Bill Brister