mine is the same..
we have to clean it with the magnetic sponge..
heheheh..
what i know from my readings, and from my observation to my snakeheads, they will not bite or eat each other..
for your information, i have bought another 2 marulioides at shah alam, behind wetworld at this day..they sold them for RM7.50 each..
but these 2 is more smaller..
and when i first put them in the tank, they seems to get to know each other..even the bigger one can bite them till death, they didn't do it..
when the smaller is not moving for sometime, the bigger will come to it and 'check' if it is still alive..
wow man!
this is awesome!
i love my snakeheads!