i was reading in this marine book and said for a reef tank there should be two inches of fish for every ten gallons???? idk if this is true so i asked you guys.....i have a 75 gal and i did the math and i would be only allowed (according the the book) to have 16 inches worth of fish.......if you guys would be kind enough to tell me if this is true or if this is just a caution i should take when applying fish to my tank..... any reply is thanked.....