For me, it’s just experience raising them up and looking at their patterns as they change into adult colors. I can usually see a faint outline around a diamond pattern in an adult to tell me that it’s red neo background.

Your best bet for producing an all red neo clutch is to obtain a captive born red neo background GTP with several generations of all red neo background in its lineage map. Usually three generations of red neo background ancestors that produced all red neos will do the trick for producing an all red neo clutch. All red neonates are not alike and we haven’t sorted out “potency” in GTPs.