Yes, sir, I remember that incident very well. As long as the male that expelled the unfertilized ova from his brood pouch hasn’t developed a problem with positive buoyancy, then I don’t think he will suffer any repercussions as a result of the aborted pregnancy. Pouch bloat can result from gas produced by the decay of embryonic material and the remains of placental tissue or other organic matter (possibly even stillborn young) within the brood pouch, if the male is unable to flush it out and cleanse it properly by pumping water in and out during its pouch displays (Cozzi-Schmarr, per. com.). That hasn’t happened with your male, indicating that he was able to resorb any fetal fry or embryonic young that may have remained despite the complications that arose during his pregnancy. It’s unfortunate that he was unable to carry any of the fertile eggs that implanted to full term, but since he was able to successfully eject the unfertilized that failed to implant, I think he should be fine and none the worse for wear as a result of this experience.
I wouldn’t expect him to show any interest in breeding after this episode. Once a female has released her clutch of eggs, she will not produce more ripe ova until their next breeding cycle, which would be about a month in the case of Mustangs and Sunbursts (Hippocampus erectus). In other words, his mate has been incapable of mating for the past several weeks, which may account for the lack of activity in that department. Now that it has been nearly a month since their abortive mating attempt, you may see your mated pair getting down to business again.
Remember the factors that influence gestation by affecting the levels of key hormones we discussed after your male expelled the undeveloped eggs, Sean? We talked about how low oxygen levels, dietary deficiencies, heat stress and other aquarium stressors can influence hormonal secretions and disrupt the pregnancy or prevent seahorses from breeding successfully. Just be patient, provide your seahorses with a nutritious diet, optimal water quality, and a stress-free environment at all times, and sooner or later they will do what comes naturally.
Best wishes with all your fishes, sir! Here’s hoping your seahorses breed again very soon and produce a healthy brood of young this time.