MSC, are you sure they are banded killifish and not the closely related mummichog which tends to frequent a bit saltier habitat. Mummichog can survive in freshwater and can even spawn in it. Mummichog and banded killifish are so closely related they can hybridize and actually their hybrids form an all female population in the north end of their native ranges. Anyways, I have no experience with mummichogs in ponds other than watching them in aquariums and a few I kept in an outdoor goldfish style pond. They are likely similar to banded killifish in most aspects.
If there are already LMB in your pond, it will be a real challenge getting banded killifish established. If you have ample shallow areas and quite a bit of vegetation and your bass population isn't out of control it is possible. However, from your previous posts, it sounds like your pond is bass heavy. So, you most likely will have a challenge getting them to take hold. Stock them in mid to late spring when they begin spawning to up the odds of them establishing themselves.
