Replacing top rim?

[DKoKoMan]

I’m no expert on this matter. However I remember my 150g had the black plastic trim and I had similar cracks on the corner seams. I almost think it’s the design to make the square corner with the plastic trim. I don’t think it provides structural support of the tank and is more of a aesthetic function. Perhaps if that’s the case, just peel it off and all is well. I guess my fear would be if there is some ugly adhesive behind it. I don’t think by any means this would mean your tank is done for.