I am moving my Harlequin Rasboras, Neon Tetras, and Skirt Tetras from a (44 Liter)11.5 gallon tank to a (76 Liter) 20 gallon tank. I would like to know if I HAVE to bring the same gravel from the 11.5 to the 20 gallon. I will be adding about half of the water from the original tank to the new tank for bacteria reasons, but I will not be using the same filter. I just want to know if adding just the water from the old tank will be fine enough for my fish.
I would also like to know if I have to clean all the decor (and gravel if necessary) before I transfer it to the new tank. Thanks!