Back to the topic, yes I agree, substrate can/is ingested on a regular basis.... look at the pebbles in my quarantine tank...... mind you it is a bare bottom tank! Every single bichir I have purchased that was kept in a gravel bottom has passed some sort of gravel/pebbles. I now have white, black, blue, red, brown, etc..gravel in my quarantine tank. Starting to look like a non bare bottom tank. 



