Roan Art said:
I think I will do some research on the red-eyes and see what's up. They sound great, but I hear what TetraBotia is saying. See if that was one of those "weird and strange occurances" -- like killer platies or something.
On this, I have a theory...
The tank was about 20 gallons, and it had about 60-70 red eyes in it. No other fish. Throw in one guppy in a crowded single species tank (especially Characins) and you kind of inadvertantly set off a territorial frenzy fed by the power of numbers. "You are not one of us- we are many- die!"
It almost seemed to be like a shark frenzy, and instinctual. Guppy in, nothing for several seconds... eventually, ONE Red Eye takes a nip at the Guppy, Guppy darts, then calm for a second or two. Then, another Red Eye nips again, Guppy darts, 2-3 Red Eyes nip while Guppy darts, pretty soon 7-10 Red Eyes are nipping at a frantic Guppy. Cycle grows until Guppy is being clobbered, sinks/swims to bottom gasping, and the only thing that is saving it (albeit temporarily) is being montionless.
That took like, 15 seconds max.
Take the same fish, and make them a small school of 6-8 fish in a community tank, where they don't "own" the tank, and they are not necessarily the biggest fish in the pond, so to speak, and you might get VERY different results.
You can see this in humans, and other animals as well...
One interesting point here is, the Red Eye Tetras were about the same size as the Guppy... it was not size that mattered, but numbers.
All theory, but I suppose others might have something to add to it.