Oh! You know this tank? Ive been searching all over for the manufacturer. I was told these were display tanks at Petco in the 80'sSorry to say but your gonna separate the panes and start fresh. If I remember right those tanks are made by D.A.S Dutch aquarium systems
A good friend of mine bought a display tank that was similar to that but it was 700g This is the tank. This pic is old maybe 08 the tank was a 3 part tank there was a tank that mirrored this one then there was a tank in the middle. I went to that shop when I was younger the whole set up is massive.Oh! You know this tank? Ive been searching all over for the manufacturer. I was told these were display tanks at Petco in the 80's

A good friend of mine bought a display tank that was similar to that but it was 700g This is the tank. This pic is old maybe 08 the tank was a 3 part tank there was a tank that mirrored this one then there was a tank in the middle. I went to that shop when I was younger the whole set up is massive.
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if the joints them selves have separated will need a rebuild, panes removed, all old silicone removed, panes resealed/glued back together, then the inside resealed. unless you are very very good DIY a job best left to a professional.