yep they can but it depends on certain factors.
There is a clear line to what is aborted and what is still born.
1 unwell during pregnancy, the fishes natural defences will abort all eggs, fertile or not in order to stay alive.
2 badly crossbred will but not always abort due to genetic disorders, some fry are dropped either still born or die soon after.
3 severe stress during pregnancy, extreme heat +/- differences, nitrates, ammonia, even white spot., confinement of long periods.
The big issue of fish aborting whilst in breeders is a common debate, the timing MUST be right, the breeder must consist of right size considering the size of the fish. Some people are so obsessed with the fact that fry are on the way that they tend to panic and place the fish far too early into these thins and only take into consideration of the size of the fish and nothing else, spend 20 mins chasing the fish around the tank will stress her out completely and then added to the stress of be confined will lead to aborted fry and even death from shock.
Some fish will cross batches i.e she will be pregnant will one batch and ready to drop, at this stage she will also allow the next batch of eggs to be fertilized, when she drops the first lot sometimes she will pass the new fertilized eggs as well so its not really aborted but just unfortunate happenings.
The dormant period is very common and infact has happened to me this last 2 weeks, as my females drop they start to swell again within 1 week with the next drop, I went away for a while and someone who was looking after them didnt feed them, so, the females held on until there was enough food and the water conditions were right before allowing the eggs to develope any further.
