Sure healthy fish will be fine not eating for a couple days once in a while. What kkiel is talking about (not feeding while out of town three days) prob only happens 3-4 times per year. EVERY weekend constitutes a much greater frequency and would mean going hungry 28% of the time. That's a big difference in my opinion.

Also, from what I've read fish DO eat every day in the ocean, many, many times per day in fact. In captivity we feed bigger meals and much less often, which is not as well suited to their digestive systems as what they get in nature.