You will know when they start eating it for sure they will come to the top for it. They look like healthy fry you wanna keep there stomachs bulged out like that. I still feed rots sometimes through day 5 or 6. Make sure there ALL eating the otohime. Go to the larger size also as soon as you can. it floats better in the water (imo). Looking at the pics the water looks pretty clear are u tinting the larval tank with any kind of algae? You need to keep the rots healthy in order for the fry to be healthy. An empty rotifer has no nutritional value to the fry. Im sure you probably said it all ready but whats your temp and salinity at?
