Figure 8's aren't effected by a lack of a "hard diet". Dwarves and 8's are the only puffers that I know of that don't need to grind down their teeth. I know a puffer fanatic that keeps a figure 8 only tank, hard foods have never graced their mouths (some of the puffer are over 2 years old now) and never an issue with teeth overgrowing.Yes, F8's need a 'hard diet'. Though I'm not sure which you aimed this at, F8's or DP's. Dwarf puffers don't seem effected by lack of 'hard diet' IME and from what I've read.