Oh and I forgot about this other alternative.
How much does aquarium-friendly silicone cost? (around what price) so that I could maybe compare it to ours, see which way I can acquire it).
I could just get glass pieces (should be easy to find), dad can cut them and build a home-made 100L aquarium. Might not even need to pay for the glass, which would cut down on the cost.
How much silicone would I need to weld such a tank? That way, the problem of carrying the tank towards home would be eliminated. Tank would be built inside the house and at lower cost than they sell it if I can get a good price for the silicone bottle.
Would this be a viable option / shortcut to an even bigger tank? Could work on convincing mom to let me keep it, but probably a bit less chances than a 64L ready-made.
Edit: Found silicone for aquarium. Seems quite cheap. I may need 2-3 bottles of this to make it, and glass should be easy to find and if not, just ordering it, will pay extra money but should be cheaper in the long run and better for the fish to have more space. Could save money for good gravel and plants, aside from the dechlorinator.
The dimensions i could go for would be 60x60x28 though, unless the table can hold about 100 cm in length, in which case I'd go for a 100x38x28 in format LxWxH. I'd prefer a low height to give the catfish easy access to the top for air. Which would be better?