Thanks everyone, Caryl, Pegasus, ajbroome, cat, dennis, bobsvinyl. The tank is now in the repair shop - fish all in their temp homes & doing well. The two clown loaches are checking out the four resident clown loaches - hopefully they will all party and hang out together peacefully. Big thanks to Macka for loan of temp tank.
Oh while at the glaziers I happened to order another tank - roomier LOL.
There were no obvious leaks, however the seepage was real. The tank is only three years old. I did not have any bracing on it. Would that make a difference?? Approximately 3.5 foot long and 1.5 feet high and wide.