Neon Tetra feeding issue

I'm setting up a new tank (29gal). So far I have only 3 neon tetras
in the tank with no other fish. My problem is that the neons hang out
near the bottom which wouldn't be a problem but they seem to not
notice when I place food in the tank. I'm feeding them flake food and
they often don't notice the food until it starts to get soggy and
float to the bottom. often it makes it all the way to the bottom
before they notice and as such, never gets eaten. I'm only feeding 3
or 4 flakes so I'm sure I'm not really over-feeding but I'm not sure
how to 'train' them to get them to notice the food floating at the top
of the tank. Any suggestions regarding this?