Goby not eating

Heyya folks. Having some problems with my fire goby. He's actually a varocious eater, the only problem is is that he spits it out right away. I know they're planktivores. Perhaps he's still getting what he needs? I've had him since Sunday, which usually will show a sunken stomach by now, which he doesn't have. That's based off of FW experience though. I've tried feeding him Hikari Marine Diet, Hikari Marine Angel Diet (both frozen), and Hikari A. Everything else about him seems fine. He's very curious, has great color, not too skittish. He even goes to his little cubby hole when I turn the lights off. My other fish kinda blunder around for abit until they figure it out. Just wanna make sure he does ok. Thanks alot.

Thanks alot Boogie. The brine shrimp did the trick.