Fwd: Anybody ever have this problem?

["Ed Pon" <edpon@hotmail.com>]

> And I must emphasize that I see this very often where the original 
tank 
>inhabitant is the more dominant (but not so aggressive as to cause real 
>fighting), which rules out the suggestion that they were picked on.  It 
>seems that the stress of the addition and/or the surge of hormones 
weakens 
>the fish and they contract disease.  It just seems strange to me that 
the 
>fish that SHOULD have the lower stress level (the original inhabitant) 
is 
>the one that dies.
>
>Any similar stories out there?
>
>Tom  (trying yet again with A. trifasciata)

I have had this happen a couple of times with pandurini.  Have you ever 
heard of the theory of growth hormones or growth inhibitors.  Some time 
ago, it was theorized that some cichlids put out growth inhibitors.  
This could be a survival enhancing trait if the waters where they live 
in start drying up and there's a lot of fish crowded together.  The 
growth inhibitors would make the existing fish not grow so large--thus 
requiring less food.  Another effect is that the weaker fish would 
succumb to disease and die.  I don't know if this theory has ever been 
proven, but I have heard that increased nitrate concentrations yield 
pretty much the same results.  

Another possibily is that the fish had gotten used to being alone and 
stressed itself into illness.  There's an island near where I live where 
the deer population had grown too dense.  I read somewhere that deer are 
somewhat solitary and that because of the population density, the deer 
encountered other deer more frequently than is normal.  There was 
apparently abnormalities found in the deer's internal organs that were 
attributed to the generation of too much adrenalin or the constant 
generation of adrenalin.

Another thought is in the past few years, a few tropical fish foods have 
started hyping the vitamin C content of their foods.  Supposedly, fish 
can only generate so much vitamin C and more is needed because aquarium 
live in a much more stressful environment than their wild conterparts, 
and the vitamin C is essential for their immune systems to work 
properly.  The  addition of a new fish could have increased the stress 
level of the previous lone occupant of the tank and may have resulted in 
the resultant illness. 

Just some thoughts on what the possible causes of this phenomena are. 
Yes I have seen it, and it drives me nuts.

______________________________________________________