I've seen this happen before and the safest thing to do is replace the tank; not a pretty prospect. But, if it's just a tiny hole, less than 1/8 inch, you might just screw in an appropriate size diameter stainless steel pan head sheet metal screw. Coat the threads with silicone aquarium sealer and then after you screw it in, top coat the srcew head and the area around it. Let it cure well before re-filling the tank. How lucky do you feel?

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