That’s human fish tank maintenance is what’s missing and causing that build up! That happens in every tank if you never vacuum it out and clean it!
That’s mulm left over as the final result of all the biological activities in you tank. Nothing eats that. In nature it gets washed away, broken down further by other bacteria etc. A fish tank is a closed system. We need to help that along by removing it manually. Not because it hurts the fish really (although for sure it’s keeping Nitrate levels higher as it’s decomposed matter left in the tank) but because it’s unsightly.
That being said, to answer your actual question, no they won’t. Snails eat dying plant matter and scraps yes, they won’t eat that. MTS snails like to hide in big piles of it, still won’t eat it.
Bristol nose plecos are very specialized feeders. They eat algae waffers, veggies and need a piece of real wood in the tank to rasp on to help their digestion and do their best. They won’t touch that mulm either.
Appreciate the thought of trying to solve tank maintenance with a fish to do it for you. We have all asked that question at some point. Me included.
But yeah it’s on you lol. best of luck!
GreekGamer05 
It’s called a gravel vacuum and a bucket my man!
That’s human fish tank maintenance is what’s missing and causing that build up! That happens in every tank if you never vacuum it out and clean it!
That’s mulm left over as the final result of all the biological activities in you tank. Nothing eats that. In nature it gets washed away, broken down further by other bacteria etc. A fish tank is a closed system. We need to help that along by removing it manually. Not because it hurts the fish really (although for sure it’s keeping Nitrate levels higher as it’s decomposed matter left in the tank) but because it’s unsightly.
That being said, to answer your actual question, no they won’t. Snails eat dying plant matter and scraps yes, they won’t eat that. MTS snails like to hide in big piles of it, still won’t eat it.
Bristol nose plecos are very specialized feeders. They eat algae waffers, veggies and need a piece of real wood in the tank to rasp on to help their digestion and do their best. They won’t touch that mulm either.
Appreciate the thought of trying to solve tank maintenance with a fish to do it for you. We have all asked that question at some point. Me included.
But yeah it’s on you lol. best of luck!
If you want to never gravel vac or do water changes, set up a tank as follows:
1 inch organic potting soil cut with peat moss, sand cap of 2-2.5 inches. Heavily plant. And I mean heavily. Add wet leaves from local water source.
Feed sparingly.
Sit back and enjoy your top offs only aquarium and your healthy, active, foraging fish.