They grow up to 1 meter. I believe So are you sure a 90 gallon isn't big enough? If not, I would go for more than 250 gallons or more.Your going to need a bigger tank that a 90 for that fish... they get really really big.... so if you want to house this type of fish you should look for 200gal or bigger, now. these fish should not be sold for hobbist but they are and many end up dead becuase the owner can't keep it. Evne worse they are release in to the native water supply..... NEVER NEVER do this. In england I do beleave these fish are illegal to sell. Good Luck