if your baby don't like it, change back using threadfin fillet. The most important thing is your baby willingness to eat, no point giving the best fish if baby don't like it But normally we use fillet to cook, so far not sure about belly, belly might be a little oiler which smell and taste might be bad.I went to the market and the fishmonger recommended the threadfin belly, but my baby vomited maybe it is too stinky. I used to buy the mid body part for my baby and he likes it. Is it the fishmonger recommended the wrong part?