By Rev DTG via AMAZON.co.uk on Jun 03, 2016
"All my tank mates seem to love spending time around (and on) these mineral blocks. I originally purchased these to provide additional food for my team of snails, shrimp and britstlenose catfish. It turns out everyone in the tank love these blocks. While the snails and catfish spend quite some time on it, all the other fish visit it regularly and give it a nibble.
The block is solid and doesn't disolve into the water in the way dry cubes of shrimp do... I have found each block lasts about 7 days. They disolve slowly into the water stream and every fish benefits from that water and is a great way of adding additional minerals into their environment, although Dave (my busy catfish) does enjoy nibbling around the sides of the cube and seems to keep him occupied for quite a bit of time throughout the day. "
Quote directly from Amazon.co.uk by Rev DTG on 3rd June 2016