Insect and Spider Identification: ID these aquatic insects?, 0 by Ehlwyn26

Ehlwyn26 wrote:
I have a tropical, fresh water fish tank and during one of my routine cleanings of it I noticed that after I had vacuumed the bottom of the tank I had these little guys floating around in the water. I have never seen insects like these before and am just curious as to what they are and if they would be harmful to the fish I have in my tank. I have attempted to remove as many as I can find, just to be on the safe side.