We consider two classes of puzzles Aquarium and Tilepaint connected to the field of Discrete Tomography. The input mixes a tiling of a rectangular grid with projections prescribing the number of squared cells that have to be filled in each row and column. In Tilepaint, the tiles are either entirely filled or remain empty while in Aquarium, the tiles are filled like aquariums with an horizontal level of water. Tilepaint is known to be NP-complete with a proof showing that Aquarium is also NP-complete, even with tiles of size at most 3. In this paper, we investigate the complexity of the two puzzles in the special case of regular tilings with small tiles. We show that Tilepaint can be solved in polynomial time while Aquarium is NP-complete for regular triomino tilings and is polynomial time for some regular domino tilings. As Aquarium is NP-complete, we propose, in a second part, a physical zero-knowledge proof (ZKP) protocol for Aquarium, using decks of playing cards (using a total of \(2mn+2\) cards for an \(m\times n\) grid).