I while back I asked about genetics & inbreeding on the old rainbow forum and Adrian Tappin pointed me to the study below. Basically it says most problems arise from not keeping fish in quality conditions rather than inbreeding. This is with larger groups of fish but it still applies to some degree in our smaller breeding efforts.
"Finally, the genetic variability within the six farmed populations was comparable to that of the natural population of Uter Lake. Because no deficit in heterozygotes was evidenced, there was no major inbreeding in these reared populations. Therefore, the problems experienced by the farmers (i.e., decline of production, higher proportion of females per spawning, loss of coloration, lower growth rate and fecundity, morphological abnormalities) are obviously not due to inbreeding depression and are probably caused by other factors such as poor management and/or poor water quality."
I don't know Rob, this is the only rainbowfish species that had a massive collection done. At least in the hundreds... As opposed yo most others where it's in the low single digits. Just look at guppies or bettas for the changes inbreeding can make. I have yet to see an animal that doesn't change due to inbreeding. It's not always for the worse but it always changes. It's up to the breeder to decide where they want to go with the fish. Our goal should always be the closest as possible to wild shape and colour, but you don't have to look too far to see changes in captive stocks... Rosario red boesemani for instance? My fear is that our precious rare rainbowfish can easily be pushed away from what they should look like in a very short time if we aren't careful. We need to remove the fish with missing fins, spine and float bladder issues, gill plate issues.... Etc. Under the best of care most species give us these.