CichlidFish.com - Fish That Think.

I was cleaning the tank that i keep my O and blue acaras in and i had been noticing shiny bits of something in just one certain area on the gravel.  Whenever I would find one i would always pick it up and throw it away.  I was curious but not really concerned until today when i found a peculiarly shaped piece of either plastic or glass. It was curved and rounded into a half sphere shape.  I took out the thermometer, which had been floating underneath the filter overspill for quite a while, i must confess i have not really checked the actual temperature of the tank for about a month, I just kinda touch test it.  I looked at the bottom of the thermometer and the bottom, which held these ball things to weight it down once it was suction cupped to the wall,  was gone.  that was what i had found on the gravel!  the ball things had all fallen out too, are these harmful to fish?  God i hope not!

Must admit, I'm not sure what goes into a modern thermometer.  I remember reading something a while back about making them non-toxic, but that was for humans.  I would suspect that they should ('should') be OK, being specifically made for aquariums.  However, we are now talking of the possibility of sharp objects in the tank, so keep looking.  I had one go on me, but it was one I used to make sure my change water was at the right temp, on 'large fish' tanks I only use the external stick on ones.

that's a good idea, i see that oh so clearly now, i had heard them banging it against the glass before but always just thought it could take it.

On that note, I take you don't have any unguarded heaters in there either ?