I don't know of any "rule of thumb" that I'd agree with... The X inches of fish per X gallons has one big problem...
6 1 inch Chromis vs. 1 6 inch Naso said:
you might be surprised how many years the "experts" included in their books those retarded inches of fish per gallon formulas.
a fish that is 2 inches in length has 8 times the mass of a 1 inch fish when sized to scale. when lngth double, mass goes up 8 times if body shape stays in scale. I've been telling that to people going back to the 80's. it wasn't hard to figure out on my own with a pencil and paper. [subliminal message: Carl - "it ain't got no gas."] just by playing with modeling clay, one should at least get a ballpark idea. [Carl - "Have you checked them plugs? It's prolly them plugs. umm hmmm..."] i've never believed much of what i read in fish books and mags. some things you have to figure out on your own by thinking for yourself, because there will always be misinformation repeated by parrots in book after book after book. monkey read, monkey write, monkey doesn't question.
The "experts" said what I was doing in the early 90's couldn't be done, and now those same experts are the "gurus" of sand beds and "no filtration", though they still use skimmers. "refugium"? my filterless tanks, including a 360 gallon beautiful show tank packed with many fish at PP, were their own refugiums. some day most reef keepers won't be using protein skimmers, and i'm sure as it becomes trend, sprung will explain with fancy formula and, as time passes, people will systematically believe he was one of the gurus of that too, with reef notes volume rocky vii. [biscuits and mustard...]
j/k