How To Tell If Zebra Danio Eggs Are Fertilized. She is full of eggs and will not lay them, she has been fat for many months. Since danios are not livebearers and female danios never carry fertilized eggs, this is as close as danios get to being pregnant.
While examining your fish tank, if you happen to feel that one of your zebra danios seems fat compared to other, chances are it may be carrying roe which concludes that it is a female one. The presence of too many fish is also a problem for zebra danios,. I bought 5 more danios (currently in a separate tank, 20g) to see if they would encourage her to lay the eggs.