Adding fish

[dismayed]

Talking to local fish store people they all seem to have a common understanding of what fish to add first, then second, etc. I'm not talking about hardiness, it's more like a general "it's always done this way" set of rules. For example at multiple stores I have heard people saying things like start with clowns a few weeks after the tank cycles, wait to put angels in until maybe 3-4 months in, wait to put coral in until 3-6 months, etc. If my tank metrics appear perfect following its initial cycle, and hardiness doesn't seem to be the issue, is this related to how many microbes my tank might support? I'm just trying to figure out what the theory is here and if it is sound. Trying to learn. :)

[Wizzard~Of~Ozz]

Most of the time the order fish are put in has more to do with 2 things.

1) Stability, the more sensitive the fish, the longer the tank should be running
2) most important, the aggressiveness of the fish being added.

You should have a list together of what fish you want, research them, put them in order of aggressiveness (consider if they are territorial as well), then in order of sensitivity.

This may mean that a rather hardy fish is added last, only because it's territorial (clowns, sixlines etc.). So shy timid fish first, then add the more territorial fish.