I have come across several examples of lycka that Folkets lexikon provides to the meaning of "luck". Lycko|sam, fiskelycka, jag hoppas att du lyckas, and of course "lycka till!" Are they all obsolete and not usable in the contemporary language (with the exception of the last one )?
Sure, I was referring to "lycka" as a separate word, which nowadays seldom means "luck". There are a few remaining constructions that have the connotation "luck" and that are still used, such as "lycka till".
I think the confusion stems from the fact that "lycka", when not meaning "joy", has come to increasingly blend with the meaning of "lyckas", "to succeed". It's a very fine line, but that's why "jag hoppas att du lyckas" actually means "I hope you succeed", rather than "I wish you luck", which would be "lycka till" or literally "jag önskar dig tur".
Your other examples, "fiskelycka" and "lyckosam", while retaining some of the connotation of "luck", could be interpreted in the sense of "fishing success" and "successful", and in the case of "lyckosam", I would say that this is actually more common. It's a beautiful word and I encourage you to use it. But if you want to make sure the reader reads it as "lucky", "tursam" would probably be a safer option. It depends on context. For some usages, check out http://www.synonymer.se/?query=lyckosam .