This is my first time raising a baby duckling, and it's been throwing up its food recently. I've been feeding is baby cereal, is that bad?? I also feed it watermelon earlier today, but the throw up just seems to be the cereal.
You mean like infant?(human?) i'd have a look at this sticky... ducks cannot really "throw up" but if the crop cannot handle what it is, may come back up.
This will help with foods and what type. How old is the duckling? as well i'd skip treats if it's real young and when you do introduce them you will need grit, again mentioned in this sticky.
I would go with duckling starter food. I found a waterfowl/turkey starter crumbles feed that worked really well. If it is not formulated for ducklings (or at least for chicks), it may be too much of a challenge for a baby duck tummy.