They sometimes lose color when sleeping. Prime @ 1-drop/gal daily will keep ammonia locked up and detoxified -- 2-drops/gal of tank size for water changes. Hand-feed him one pellet at a time. You should be able to see a slight stomach bulge when he's has enough to eat, or a loss of enthusiasm for eating.
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Hey Halyx.....so many questions. My betta appeared lighter in color when he was sleeping, or am I delusional? Ammonia is still over zero...accck! And he is a voracious eater (and beggar) but I don't want to over feed him. Too many ???'s