These guys love their seaweed, and the dollars used to like lettuce but no longer. I also believe nori is better for them, cheaper for me, less polluting, and closer to things they may eat in nature despite being marine. Also, this way they don't eat the aquarium plants.
Four tanks - 1) Silver dollars (Metynnis , 3 spp.), 2) Flagtail + friends, 3) M. boesemanni rainbows (young, growing up), 4) Congo + lemon + cardinal tetras (young, growing up). As shown, competition with bushy-nose plecos can be fierce, even if those get their own treats at night.
Cheers,
Francisco