The nail breathes oxygen to live. The nail breathes the oxygen dissolved in the water.
Given that the aquarium is a small bioma there is not enoguh source of oxygen to replace the oxygen consumed by the snail, except for the oxygen produced by the aquatinc plants inside the aquarium.
Plants produce oxygen through the process named photosynthesis. Photosynthesis requires light.
Given that the aquarium is kept dark, the aquatic plants cannot carry out the process of photosyntthesis and so there will not be generation new oxygen and the snails will die after they do not have oxygen to breath.
75% of the kernels born will be Purple, the dominant gene. And, 25% will be the other color. The phenotype might be 3:1 i think, well need anything tag me :)
