I used to live in Phoenix, Arizona and cockroaches were a fact of life. No, I'm not a slob - lol - it's the climate there. They're as common as crickets (used to feed my Oscars crickets I caught on the porch, they loved them). My tank was located in a den, not in the living area. When I had to bomb, which was probably once a year, I turned off all pumps and filtration, placed a towel across the top of the tank, opened the window, closed the door and taped off the entire den door with masking tape. I then set off the bombs, which after doing so you have to leave the premises for about four hours. I never lost a fish, but I took good precautionary measures to guard against it. If I felt I needed to de-bug the den, I'd simply use spray bug killer along the wall bottoms and in the closet, again only after shutting everything down and opening the window.
If your tank is in a living area, or in any area that cannot be sealed off, you're taking substantial risk at killing your livestock. That stuff is extremely deadly and permeates everything.
There are much better ways of dealing with bugs than bug bombs. You can buy concentrated insect killer and a one gallon pump sprayer (at least in the U.S.) and spray the areas that really need spraying, such as under kitchen and bathroom sinks, and along walls at the floor. It's just as effective as bombs. Bombs are a mess.
Everything in your house gets that crap on it. Plates, silverware, clothes, you name it, it clings to it and if you don't wash everything you're liable to end up with an ear growing out of your forehead. Use a pump sprayer instead. I used bombs at the time because I was single and didn't own much. I could wash all my dishes in one load in the dishwasher and most of my clothes in one load in the washing machine
Kind Regards,
Steve