If what you mean is, are there any fish, that eat fish waste (feces).
None
If you mean, fish that eat uneaten fish food, plant scraps, etc, then yes, some plecos and other bottom dwellers, but then they produce at least the same amount of waste, that they have eaten.[/QUOTE
thats not very true.... No offense. Tilapia will eat their own feces and can. Be happy as can be. Obviously you want to feed them NLS or something to break it up