Let me add many fish can and will survive and thrive on prepared foods. I'm currently feeding my fahaka mostly pellets. It's rare to get a puffer on pellets first off. Secondly, I don't know long term if they are hard enough to wear down it's teeth and provide all the stuff it needs for proper digestion. There is "talk" that the bits of shell they ingest helps in digestive motility, how true this is I don't know. Fortunately for me I started trying feeding pellets right away after I got it and it took to them very quickly. I feed pellets, crayfish and snails on a rotation. My crayfish stalled in breeding about 6 months ago, and my snail culture just crashed. I have other snails in other tanks but if I was only feeding those I'd be hurting.