The Balrog is a cousin to the Sylvester, and one of the aquatic aliens that can be encountered in the Insaniquarium Universe. It often accompanies its relative in hunting trips, and sometimes is spotted with the Psychosquid.
Balrogs are similar to Sylvesters in appearance, but they have golden skin and more evolved arms. Due to stronger arms, it no longer has as large of claws. It also has a set of red eyes, and long red hair along its head with a well-developed finned tail. It is described as resembling the mythological Sea Lion of legend.