I believe Randy is correct that high nitrates won't kill anything. It may give then a headache or the heartbreak of psoriasis but that's about it. Unless we are talking about some very colorful SPS corals, they don't really like nitrates of 100 but even that should not kill them. Not right away anyway. It certainly won't affect the fish.
What your tank needs is more bacteria, not more water changes. Whatever you are putting in there, partially eaten crabs or aardvarks I don't know but if you just change the water, the nitrates will continue to climb unless you increase the bacteria. Vodka may help, (put some in the tank also) but vodka will only feed some more bacteria "if" they have a place to live. Remember all of the available spaces in your tank are already taken up buy other bacteria (as well as dead crabs and aardvark parts) and those existing bacteria don't like to give up their space to new, possibly illegal alien bacteria so you need to provide more surface area for them to live.
Just my opinion of course as I am not the God of nitrate. Randy probably is though.