Breeding F. deltense can be a big of a chalenge:
"I recently Tried something different while trying to breed F. deltaensis "Patani". Previously, I had tried breeding these murderous brutes in bottom mops with no success. I watched them breeding but when mops were pulled they were no eggs. Tried using peat on floor of smaller tank but the males was just too brutal on the 2 females. So I decided to try breeding them like Nothos. Went to Target and found these big 7 inch diameter glass containers and put in @ an inch of peat. Put the container in a 20 long. The tank contains my 2 female breeders, the dominant male and 2 subdominant males. Now "Brutus" spends a good deal of time beating on the 2 subdominant males & actually spawns with the 2 females without brutalizing them. Got over 2 dozen eggs from 2 weeks of spawning today all look fertile. Put another batch of fresh peat in today. Apparently as long as he has some outlet for his aggression he plays nice with the girls." - Robert DeKeulenaere, Feb 5 2020 FB