The aquarium has glass lids but arowana was strong enough to jump through one of the lids. I should have had more weight or clamps.
I put a sheet of 2" thick hard board insulation on top of the tank over the glass lids. I strap it down w/ a section of parachute cord. The top of the tank toward the front is filled w/ planters, lava rock and pothos which is removable for feeding but too heavy for the Aro to move if it attempted to bail out. It helps mitigate heat loss as well. I still hear that dude hammer the bottom of the lid every once in a while but I'm def not interested in losing another. They are definitely predictable and the vast majority of Arowanas check out in the same way.
