F8 wont eat live food

[klobie]

I am a relatively new PufferMama so there is still a lot for me to learn. I have an F8 that is about 4.5 cm so Im guessing not fully grown because Ive read they can be about 8cm at most. I fed him a ghost shrimp once that he ate almost right away (normally I rotate different frozen food. but frozen is boring.) So a week or so ago I got another ghost shrimp for him that he harassed for a bit but never ate. It's still alive! Ive literally seen them swimming around together. The shrimpie is like maybe 2cm at most so what my question is: Is he too big for my F8? Why would he not want to eat the shrimp? I asked my LFS buddy about it and he said since hes not fully grown, maybe hes not ready for live food? I want to feed live stuff once in a while for beak-related reasons and because it seems more natural for them. Is he not ready? Or should I try something different than a ghost shrimp? The freshwater snails at the LFS are way too big for him and Im still transitioning to brackish so I wouldnt be able to feed him saltwater snails. Right? Because they have ittybitty ones at the LFS. Would I be able to feed him those once it's fully brackish? Thanks in advance for any tips!

[Pufferpunk]

I am afraid your tank is all wrong. Your puffers are brackish fish & they are living with fish who won't appreciate any salt at all.
As far as snails, you can crush them with your fingers to make them more palatable for your puffer.
Here are a few articles for you to read:
library/puffers-in-focus/fig8/
library/category/feeding/

[Welch4]

Welcome! I have ghost shrimp that have been in with my gsp for a month now hasn't touched them. Nothing to worry about just keep its diet varied. The saltwater snails have much harder/thicker shells than pond and ramshorn snails. If you wanted to attempt to feed these I would recommend going with PP suggestion and crushing the shells.

[klobie]

I should have mentioned before that the guy I bought him from was keeping him in Freshwater. I had already planned before I got him to transition to brackish so thats something Ive been working on. But at this point Id say Im still mostly freshwater. I wasnt sure if (when the water is brackish) I would be able to feed him saltwater snails. 'Cause they are much smaller and seem more doable for him to eat.
The freshwater snails, like zebras, were waaay too bigg for my lil guy. This is why I went for the ghost shrimp, figuring since theyre so small and fragile-looking it would be easier for him to eat. im not sure what else live food I could/should feed him.
If my tank is "all wrong," what should I be doing differently?
I realize I am new at this but I wanted to get an F8 for a long time and put a lot of research into the breed and then found a good "Mom & Pop" fish store to get him from. And, of course, Ive done a lot of research since. So if there's anything you can teach me, I appreciate it! That's exactly why I posted this question