Well you will have to find out how many gallons or litres the tank is, need stats in ammonia,nitrite,nitrate,and ph, how many fish and which type.
Plus any symtoms before they die.
he got stuck behind my thermometer then jumped out the water and back in, then he went beserk and started going up and down the sides of the tank and then hit the bottom and died.
i havent tested the Ammonia/Nitrite/Nitrate, plus the were undersides were ripped open?
Poor thing R.I.P.
Need to get stats done, if you don't have test kits take a sample of your water to the lfs and tell them to write the readings down for you.
I would recommend a water change.
As for your tank, you either need to invest in a test kit or go to your LFS with a sample of water and ask them to test it. Its the only way to tell what killed all your fish.