well the answer is "no" and "maybe" - the "maybe" : that depends on what method of cycling you used.. If you cycled a tank by putting in 3 or 4 small fish (like Danios) then no, you can't add more than "maximum capacity" at once - you should add one or two new fish at a time, at which time you'll notice slight increases in ammonia and nitrite until the bacterial colonies responsible for removing it "grow" to meet the new demands (a week or so perhaps).. if you did a "fishless cycle" according to the conventional "recipie" then when the cycle is complete, you can add "maximum capacity" all together at once immediately after the cycle completes. This is because the fishless cycle yields a much larger, healthier bacterial colony than a handful of small fish would, and in a much shorter time..
the "no" answer from above is this - regardless of the method of cycling, you sholdn't add "more than maximum capacity" - the cycle method only yields the ability to add fish slowly or all at once - the total amount of fish though, shouldn't be more than the tank size can handle regardless how fast or slow they are added to the tank
Hope this helps