Yes, puffers are predatory carnivors (crustaceons). I have observed them eating algae wafers & peas, on rare occasion. I have a few very active FW puffer species (to the point of constant, nervous pacing the glass) that are around 2-3". They get fed daily, skipping 1 feeding/wk. At each feeding, they are fed to a nice, round belly. Even small, fast-moving FW fish like zebra danios & neons, are only feed 1x/day, 5-6 days/wk. I am new to the SW end of this hobby (been in FW >27 & BW >5 yrs). It would strike me odd that so many SW fish would require that much more food than the FW/BW species but I'm always learning something new in this hobby! (Now on the other hand, my discus, which are kept at 86 degrees & have a very high metabolism, are fed 2-3x/day but I still skip 1 day/week.)
This feeding method has always worked for me--of course, there are exceptions to every rule...