It rather depends upon what you mean by "waste" (I think we all know what algae is
). If you really are meaning fish waste, only bacteria and snails will consume that. If you mean uneaten food, some fish might pick bits of it, but not reliably. Here again, snails are your friend; reducing the amount fed to eliminate it is advisable. The fish waste should be allowed to settle into the substrate where bacteria can convert it to organics and nutrients for the plants.
There are fish that eat specific types of algae; several (otos, some but not all plecos, Farlowella) will eat diatoms (brown) that usually only appears in new tanks during the first copuple of months, and these also eat common green. Brush algae will be eaten by the true Siamese Algae Eater, but they get large (6+ inches) and are not appropriate for a 29g tank. Some regular fish like mollies will nibble on algae, and rift lake cichlids do (the mbuna grazers). My pencilfish Nanostomus beckfordi frequently pick off green algae from plant leaves. But not to excess.
I'm not a fan of having algae-eating fish solely for that purpose. First, they frequently do a limited job (too specific as noted above) and they add to the bioload themselves; if it is a fish you really like and want as a fish in its own right and it happens to eat certain algae, that's different. Like my Farlowella that are to me fascinating fish, and they are ravenous algae eaters but only the common algae, but they keep the plants spotless. I have a trio because I really like the fish; their algae eating is a bonus. Keeping the light duration minimal (sufficient for the plants in balance with the available nutrients) will usually keep algae from being troublesome.