The dolphins are fed 4/2 = <<4/2=2>>2 buckets of fish each day.
The sea animals are fed 4 x 5 = <<4*5=20>>20 buckets of fish each day.
So, the Mystic Aquarium needs 4 + 2 + 20 = <<4+2+20=26>>26 buckets of fish each day.
Thus in a week, it needs 26 x 7 = <<26*7=182>>182 buckets of fish.
Therefore, 546 buckets of fish will last for 546/182 = <<546/182=3>>3 weeks.
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