grosse gurke said:
The following is Pure speculation:
I think it may have to do with their behavior in the wild. Spilo CF I believe shoal with reds and/or cariba in the wild, which is why they have mimicked the color, so they can blend in. If they do it in the wild, I dont see a reason why they would not be more apt to do it in an aquarium.
I dont think gold spilos shoal with cariba or reds in the wild and therefore would not be as apt to do it in an aquarium.
Like I said though, this is only a guess!!
That makes sense to me,
and if my memory serves me right, spilo's feed on the fins of the pygo's they share the shoal with in the wild. I don't think they will stop doing that once put in an aquarium with reds or other pygo's. But in an aquarium, there's not much room to hide (even in a 100 gallon with only 2 or 3 reds), compared to the situation in the wild (where the spilo could easily retreat from the shoal alltogether), and therefore confrontations in a tank are inevitable, with the consequences we all know...
And i like to add that in the wild, when a single redbelly perishes due to the injuries inflicted by the spilo, it's almost unnoticable (it's insignificant when you look to the total number of fish in the shoal): in a tank, with a very limited number of fish (by definition: even in a 1000 gallon tank the amount of fish in a shoal is limited, compared to the situation in the wild), you'll immedeately notice the difference. Maybe wild spilo's do cause pygo victims as well, but does it just go by unnoticed.....
This is just a little contemplating based on what Jeff mentioned: just guesses, no more, no less...!!!