Completely agree with TwinTank ... very sensitive livestock. I had 4 when I got my first 28 gal planted tank. Oto's were the second live stock to be introduced. One of them died just few weeks after introducing & second one jumped off the tank sometime in the night. The later I introduced 2 more to make the number to 4. Now that the tank is totally matured and with a lot of algae for them, they survive. To be on the safer side I do drop a tropical algae wafers once in 2 days & they seem to enjoy feeding on them.