Many LMB's eventualy starve....... and that is a shame being the great little guys they are....... Here is a post of mine that I have copyied and pasted many times over the last several years in order to try and help the little guys..........
I think a lot of folks have this same issue with them. I for the longest time, had issues with mine. After dropping tabs and hooking sheets to one of those little Algae sheet hangers for what seemed like ever fearing he was about to starve. Here is what seemed to eventually work for me, was hanging a wetted sheet of algae over the from center support of my tank. As the sheet softened I took parts of the sheet and mashed them between my fingers so it would flow with the currents in the tank. It also seemed to help with the snails and other critters in the distribution of food for them. In short time he started chasing and eating these bits.
Now days Benny the Blenny has a fat belly and comes up and eats pieces right out of my hand!! Good luck with mine they become wonderful fish with some time and patience....... Warren