I don't know if that's generally tru, but i have had some problems with my blonde guppies. Mine are mostly clear yellow and don't have the red eyes that I think they are suposed to have to be true albinos. I've had some with crooked spines and they seem to generally have a slightly lower survival rate or shorter life span than my darker guppies. I don't know if that really means much though. Jill is the only blonde guppy I bought and I've had her almost 2 years now. She's the only guppy I have left that was not born in my house and she seem perfectly healthy. I think mostly she just never produced as many fry as her darker tank mate did. There were only two blonde males that were regular male guppy size and they both died at about 1 yr old or younger. I have 4 tiny blonde boys that i think must be half Endler's. They are fiesty and active and apear very healthy. Jill is small, but my second largest female now is blonde. I think I have about 5 other blonde females left and they seem to be doing about as well as their darker sisters except that one has a noticably crooked spine that was not obvious until recently. She also has just started showing signs of dropsy and is unusually thin, so i suspect she won't be around long, although her whole tank is being medicated.
My doctor put some of his guppies in the tank at the office and when I found out they were his I told him about the croked fishes I had seen in his tank. The ones I remember specifically were both blonde females. One looked simiar to my sick fish and the other was smaller and her spine was so crooked it looked like she was swimming upside down because she had a back hump instead of a belly bulge. When we went to look they were both gone, probably dead and removed if not eaten.
That's my personal experience, but I have also had plenty of sick darker guppies. I have heard that any "fancy" male guppy is less hardy than females and probably other types of guppies in general. I've had a difficult time with snakeskins, but i don't know if they are generaly less hardy or just less common or if I just have bad luck.
