digging clown loaches?

[Erised]

Ok, so I knew they'd look for food in gravel, dig around a bit and stuff ... but this morning I woke up to find this huge pile of gravel! I've had them for quite a while now, and have Never seen this behavior ... any idea why they did this??

 

[Loach Man]

My clows don't dig for some reason, and my substrate is sand, and I did sand because I knew clown loaches like to dig

 

[David]

Do you have any other fish in your tank that have a tendency for digging? Maybe they did it.

 

[Erised]

Nope ... I'm afraid its "mums tank" as in ... it got loads of guppies! there's 1 chinese algae eater which I really do not see doing this... so it must be the loaches