Question

why marine fish when thrown under tap water bursts

Answer 1

marine fish generally lives in salty water means it has a problem of exosmosis... facing the problem of dehydration
so when this marine water is put in fresh water(tap water) then the water tends to move inside the body of fish as concentration of salt is more in body fluids of fish that in fresh water so it bulges due to endosmosis...and bursts

hope it helps u dear friend

Answer 2

Fish live their lives completely surrounded by water on all sides. It surrounds them externally in their habitat and also comprises much of their body mass. Fish must therefore strike some sort of balance between these two separate, and very different, water environments which determine so much about their health. This balance is met through the processes of osmosis and osmoregulation. To explain osmosis, we'll first discuss the concepts of diffusion and equilibrium. All molecules have energy associated with them known as kinetic energy. This energy of motion allows for the random movement of molecules throughout the space which they are in. A cell placed into a hypotonic solution will have water rush inside of it (where solutes are more concentrated) and cause the cell to burst.