Slokam 7

The slokam explains that the fish was not only huge (a lakh of yojanas in length),  but was also luminescent.  This is the inner luminescence that will develop on attainment of enlightenment.  The Paramathma clearly tells Arjuna that in His higher worlds, there is neither the sun nor the moon to provide light. 

The inner luminescence will be the only source of light in the higher worlds.  The higher worlds will not provide any inputs for sustenance like earth.  By the time we transcend to the higher world,  our capability to be self sustaining should be fully developed.  That capability,  including the luminescence is the endowment of the Pagaramathma.

The rishis are elated to see the appearance of the huge fish with horns.  They have the sagacity to recognize that it is the Paramathma that has come to guide them.   Under the guidance of the Paramathma,  the tie the rope in the boat to the horns of the Matsya avatar of the Paramathma.

The ocean of our life is not only vast,  it is very rocky, unsteady,  scary,  and completely befuddling.  To transcend this life,  we need to fix the rope of our consciousness to the Paramathma in a steady and unflinching manner.  The monstrous distracting waves of this world will not have the slightest impact on us.  A seemingly dark, dangerous and unfathomable journey will be transformed into an absolutely tranquil, elevational  and illuminating voyage through the universe of life and beyond.