Missiles are projectiles fired by Destructor in Insaniquarium. They are first shown alongside Destructor's first appearance. Of course, since this weapon is a projectile, your fish can be saved by Angie after being hit.
Destructor will fire his missiles at your Fish. The number of missiles he fires depends on how many fish you have, but he will only fire a maximum of three missiles at one time. There is a red target on the random Fish it will shoot. Destroy them by clicking on them before your fish get killed and then shoot Destructor. Destructor repeats the pattern again.
During the final battle if you want to save all Pets, it is recommended you kill all the Mini Sylvesters and only the missiles when destroying Cyrax rather than killing Destructor.