[Forge]

Over the last 2 years, my aquarium seems to have been healthy. A pygmy angel, a crab, and some 'shrooms have all done well for themselves.
The catch is this: over the course of time, I have added a hawkfish, a royal gramma, a swissguard basslet, and a 6-line wrasse. None of these fish are known to be hard to maintain. The hawk lasted a month; the gramma lasted about 3 weeks; the basslet actually went about 7 months; and the wrasse lasted 2 days. The tank is 29 gallons, and none of these fish lived in it at the same time. That is, they all shared it with the angel, one after the next. I have observed the angel harassing at times, but never to the point of leaving marks, torn fins, etc.
My question is this: In a small tank, is it better to have an odd number of fish? For instance, would just 1 fish or 3 fish be better than 2, maybe for heirarchal reasons?
If this sounds like an odd question, well, that's what I get for trying to think in the shower.

[the_blue_tuna]

You should try making the water a little warmer . Actually that is a valid point when dealing with the same species ie; 3-5-7 green chromis for instance. But I have never heard anyone apply that principle to total tank inhabitants , regardless of species.