I can't tell. I can't see the spine on my other fish, but they're more 'fat bodied' fish anyhow - a clown and a allen's damsel. He eats like a pig, and likes to swim around quite a bit. I feed him a varied diet including NLS pellets, nori (he LOVES nori), Formula 1 frozen, Formula 2 frozen, and frozen mysis shrimp. I have not seen him refuse any type of food. I usually feed pellets in the morning, and nori or frozen at night. If I do nori - I put frozen in as well since my other fish don't eat nori.