Always...
always...keep her guessing and off-balance.
If the fish room is wife-unfriendly...and I strive to keep it so...she won't visit often and won't stay long enough to count up the tanks or the fish.
If you always pack a cooler and airpump in the car before a trip into town...even though, in most cases, you aren't taking fry to trade in...she will become accustomed to it and won't ask...so, if the cooler has a bag of fish in it on the way home, who's to know?
If you always have a pair of rubber boots, some rope, a saw, a shovel, an axe and all the other accoutrements of driftwood-collecting in the truck...she'll just stop asking.
Finally...and this is important!...all tanks in the fishroom or elsewhere, whether or not they actually contain fish, must be kept full of water and bubbling
at all times! Some decor...which suggests that there are fish in there hiding...is essential. This serves multiple purposes: it gives you places to store and soak driftwood to get it waterlogged; it gives you instant access to emergency tanks for quarantine, for hospital use, for fry growout, etc...plus, of course, it keeps my wife in the dark about how many fish and other creepy-crawlies are actually in the house at any given time.
The basic idea is that you are attempting to create a sense of "exhausted resignation" in your spouse's mind. You know what I mean; it's just too much trouble to actually figure out what's going on, so why bother trying?
My new book, "The Married Aquarist - Tips, Tricks and How-to's" will be available shortly.