I see that you have only a ten gal. tank and only one fish. I would hesitate to put a whole cube into your tank at once. I think that would be way too much food. Of course, I may be misreading/misunderstanding the posts.
I would slice off a small portion and swirl/swish it in the aquarium water, or, if you are going to rinse it first, swish it in tap water (or r/o water). I do that, then strain it through a real tight meshed net, then pour aq. water through the net to to dislodge that into a cup, along with the aq. water, then feed it to the fish/tank.
I have a perc. clown and feed him frozen "formula one". It is a reddish cube. I slice off 5-6 real small pieces and pour it into the tank. It is more of a gelatin consistency and stays together more so than breaking up like frozen brine shrimp does. This is about the only thing my perc eats. He really goes after it.
Frank