While both fry and adult dwarfs can be sustained on bbs, it is somewhat nutritionally void and is best fed as day old enriched with various supplements of your choice.
Copepods are a great food source, however, it is very difficult to sustain a culture large enough to be a sole food source.
I vary my dwarfs diet of bbs. Some days I feed newly hatched (6 to 8 hours old), other days I feed 1 or 2 day old bbs enriched with either Selcon, Nanno paste, DT's, vitamins, etc. That seems to be enough to keep them thriving and doing well.
Most of my remaining dwarfs I've had for about 16 months. My oldest dwarfs, a bit over two years in my care, died awhile ago. Unfortunately, as is relatively common, I haven't had any fry since last summer. Breeding is common the first 4-6 months, but seems to taper off after that.
After discussing it with other dwarf keepers and those breeding seahorses, we've come to the conclusion the lack of fry is most likely a nutritional issue with the adults. While they are active and doing very well, 'something' is missing either in their diet or their environment.
Tom