Once the Fishing mini-game began, you can only fish in
the Lower Reaches fishing spot. However, you can unlock more
fishing spots when get to certain requirements.
Use a lot of wind magic (Aero) on him and attack him
physically. He will go down fairly quickly. To defeat him very
fast, make sure you are at full MP and summon an Esper. He will
help greatly in battle.
Have the following party order: Fran, Basche (party
leader), Vaan, and Vossler. Equip a character with low magic (in
this case Basche) with the Nethicite, as this makes magicks take
half damage. If you have the Evil Slayer, it would be very
helpful. Buy a lot of Handkerchiefs (oil remover) from the NPC
outside and some Phoenix Downs. Before entering the altar to
Belias, have Fran cast Protect and Shell on everyone. Next, have
Vaan do the healing and Basche do the hitting. Have Fran cast
Water and Slow on Belias. When Belias is at 40% HP or less, he
will cast Firaja (different from Firaga) on you. This creates an
Oil status which makes fire hurt a lot more. Cure this with the
Handkerchiefs, and cast Protect and Shell on Basche. Keep this up
and eventually you can acquire him as your first Esper (summons).
