What is the worst fish to keep in a community tank?

[eddyq]

alright then, worst case scenario then. What is the worst fish to keep with any other fish?

Bad fish combo would be (no snail in tank) puffer nipping on corydorus bud.

On the other hand, the worst case scenario is when water parameter is bad.
I mean eye popped out,mouth rots,itch,s-sign.

[Jungle-mania]

I and a another guy have had 2 inch cigar fishes nipping the tails and fins of their arowana tank mate. The arowanas WERE 1.5 to 2 feet in length.[/QUOTE]

What happen to your arowanas?