My endlers are from a rather small population and are doing fine with no real problems. If you have a highly developed line bred guppy cross, it may be weaker because of indiscriminate breeding but there is no faster way to improve the health and durability of a line of almost any animal than inbreeding. With inbreeding the bad recessive genes get reinforced and become apparent. By culling defectives, you will improve the overall genetic health of the remaining animals in the group. It is a terrible idea if you are not willing to do the culling but can be an excellent way to develop a good line if you are willing to do the needed genetic cleansing. Many endlers that you encounter are not bred with large numbers but instead are bred to develop a particular characteristic. That means keeping the sample small and lots of inbreeding. Because you don't know how that breeding was conducted, you can't easily predict if it will be a problem. If you get a bunch of endlers that look like a mix and match bag of different fish, they are a tough as nails fish like the naturals that I keep.
