Fish Nibbling On Gravel??

[disasterfullife]

I have two swordtails and a red tail shark. They get along great and the tank is running great. I always catch them nibbling on the gravel, plants, etc. Just curious what they are eating or doing? I'm sure this is a very noobish question but thanks for any help!

 

[kev_kb]

Don't worry, they're eating bits of food and algae from the bottom, perfectly normal.

 

[disasterfullife]

Ok, that was my first thought. Thank you for the help.