For a fish to be buoyant, or float, it must displace less water or the same amount of water as its own body mass. ... Many fish use swim bladders to help them with quick depth changes. These bladders fill with air to help fish rise or release air so fish can sink, often in conjunction with forward movement.
Well there part of a group called carbohydrates ,sugars are monosaccharides, or single units of a specific molecules such as gluclose,fructose,and monasse . startches on the other hand ,are polysaccharides ,long chains of chains of single sugar molecule subunits linked together, if this doesnt answer your question just txt me,thxs love