I recently moved house, whilst lift the tank I cracked it near the bottom & & join, it doesn't appear to leak water but I want to be safe. how can I repair it please
Did you lift it when it had water in it? That's a no-no, I'm told.
I would look hard at getting another aquarium. I would never trust this one with water in it. It could start dripping or leaking at any moment, and maybe get water stains or even ruin whatever it's on. The peace of mind would be worth the cost of the new aquarium to me.
You can get silicone sealant at the pet store or hardware store. Whether it works or not is another thing. I'd take the previous posters suggestion & get a new aquarium. And don't pick it up again when there's water in it!