i just got my mbu today and i just feed him krill shrimp from petco. i think he was hungry because i putted my finger up on the top and he was going after me. i hand feed him and he spits it out! he chews it then spits it out! he is about 4 in
It's just food he's not use to. All fish will do this when introduced to something new. Give him a small crayfish, and I'll bet he won't spit that out.
puffers do need a varied diet, so things like mussels, crays, snails are good for trimming teeth, while scallops, squid and market prawns can be used for a little more variety along with blood worms if you want...
What do you mean pretty sure? What did you do to cycle it? How did you get the bacteria to support that kind of bioload. I ask all this, because fish that are in a tank with poor parameters will not eat.
You are aware he'll only last about 2 months in there? What are your plans for upgrading him?
That little guy is going to need a MONSTER tank. Id quit the krill diet and move on to some of the other mentioned foods until he takes to all that. Variety is good. Biggest concern here really is your tank size, and lack of knowing if it was properly cycled or not. If your "pretty sure" im guessing you havnt tested or know any of the parameters of the water, meaning the fish is not gonna eat, let alone be healthy if most likely the water isnt in that good of shape.