There's no guarantee that this accident wouldn't have occured if the arowana was in bigger tank. Arrowana jumps, whether tank is big or small, whether lid is well secured or not!. One of my friend has an arowana jumped so hard that shatter the lid, and died from head injury. The fish was still in the tank. I had the same incident wih a 12in arowana in a 180gal tank with a few clown loach. It was doing fine in a 60gal tank, until I moved it to the 180gal tank, and it got skittish since, died a couple week after it was moved to a bigger tank, smashed its head so hard. Some arowana gets more skittish when it's in big tank. Bottom line, thing happens! No need for lecture, since the OP was getting a bigger tank for his fish, which meant he know and has concern on his fish.