yes
just about every fish if its small enough to fit into their mouth you have better luck asking what kind of fish doesn't eat newborn fish.
No , the parent will eat it.
Yes, otherwise the parent or other adult fish may eat the newborn fry.
Newborn crawfish eat many types of small water animals and plants. They are known to survive on frog eggs, parts of plants, insects, and some small fish.
Highly recommend separating the adult fish from the newborn fry or you are likely to see the larger fish eat the young, even the parents of livebearers will eat their young.
Try to put them in a new tank so they mom or other fish won't eat them
at newborn they can eat plain yogert and milk when they grow a bit,they can eat all yogerts and meat or fish, when they are one year old,they can eat everything.
This is mostly universal with any newborn fish. They typically will head straight for the first plant they see to hide from adult fish who will happily eat them.
Because they are still newborn
Newborn fish are called "fry".
Whether or not a fish will eat its own young greatly depends on the species of fish. For most fish, like goldfish, they will gladly consume any unhatched eggs of fry in their immediate area. This is often why fish lay so many eggs- because so few actually survive to reach adulthood.