would be ok in a 75 for a little while, but remember these things get a foot long and like massive space to swim or it will stress out and bad things will happen. So yes when it is still 4 or 5 inches it will be ok, however tangs grow pretty fast so that wont last long. BTW were these sites that said they would be ok in a 70 you saw commercial sites? If so, toss that info out the window, commercial sites will put anything up in order to sell products, not even this site is safe from misinformation which is why you should listen to forums like these to make your decisions and not theirs.