Do all fishes have swim bladder? Justify your answer?

Give a small answer please

Lol I never thought swim bladder actually exists.

Well fishes that have bones contain swim bladder , while cartilegenious fish do not contain swim bladder. It is basically an organ fillled with gas allowing fish  to control their buoyancy, and thus to stay at their current water depth without having to waste energy in swimming. So only bony fish have swim bladder while cartilegenious fish do not.