Do certain fish use sand substrate to digest their food?

[kv2wr1]

I've heard from somewhere that certain fish like tangs actually ingest
some sand to help them digest their food. Is this true? I've seen people with bare bottom tanks have tangs so I have always wondered this.

 

[PSU4ME]

Yes it is true..... But which fish I'm uncertain. Same things with pigeons, they ingest rock particles to help grind in the gut.

 

[Doogle]

Parrot fish eat live rock and hard corals and crap out sand!lol nice pretty fresh sand

 

[BigAl07]

Some fish "make" sand by biting/eating rock. After they digest the rock (really what's in/on it) they excrete it as sand. This subfamly (Scarinae) of the wrasses and are commonly called Parrotfish.

 

[Doogle]

They have HUGE funny looking buck teeth/ beak I think.lol good call Al!...i love animal planet and nat geo.