Do you freeze it first? I used to use Rhomaine lettuce but I froze it first to help break down the cellular structure to make it easier to digest. I read to do that somewhere but can't seem to remember where.
I just place it between two magnets to hold in place while they eat....It last longer that way....sometimes will last a day or two...and I have a lot of tangs.
The only greens I feed is Nori. It's extremely cheap at the Asian market and my clowns, blennys, fox face, tangs, and snails love it... anyone else use it?
I also use it in my 'blender chow' I mix up. The 'blender chow' has pink/tiger shrimp, mysis shrimp, nori, oysters, left-over fish flake, sometimes clams, and saltwater.
ziploc bags...... make sure they're totally flat, and you'll end up with a thin flat brick like brine shrimp packs. I then cut the bags, with the frozen food in it, into squares and pile them into a large container, which goes into the freezer, and feed from that... I'm lazy, so I actually just dump a few aquares directly into the tank, the way my water flow works, it ends up tumbling and tumbling in the middle until it thaws