We finally managed to tumble some rostratus eggs to frt they about a half inch or so now so we are feeling a little more confident they should make it. We have never seen such strong fry before my wife found that by using a fine strainer and a air difuser I think it was called we have had good luck tumbling eggs these little rostratus swam out of the strainer with their egg sacs and were free swimming and you can almost see them grow.