Leaking aquarium.... gah!

I bought an aquarium today, just a small one, 50 liters, but very nice hexagon shaped. I've spent the last hour or so setting it up and filled it with water, just to find out that it LEAKS!!

[insert favourite words here]

Lucky I didn't buy any fishes yet. I was going to do that tomorrow, when things were ready, water temperature right etc... That shop is going to hear a few nice words from me tomorrow...