He looks good! Definitely stick to crunchy foods as much as possible, but if necessary, spirulina brine shrimp are a better choice than regular brine shrimp. Puffers get very little veggie matter in their diets. When he moves to a bigger tank, use the current tank to breed snails for him. My wife's GSPs have Molly tankmates, so I also drop in a dozen ghost shrimp each month to satisfy their hunting desires & keep them from eating any fish fins. I also remove molly fry ASAP & feed them to my loaches at work. Fish is not good for the puffs...