(Correct me if I'm wrong) but I think its in Lilicove City, the beach area, using a Super Rod It's actually Mossdeep city:)
You can't catch staryu in firered only in leafgreen or ruby or sapphire or emerald.
First of all it depends on what route your fishing in but you catch these pokemon: Magikarp, Staryu, Carvanha, Horsea, Psyduck, Goldeen.
Staryu
You can use either the good rod or super rod the super rod will work more often for finding staryu.
using a super rod in the lilycove waters
You catch staryu in Mossdeep city right behind Stevens house.
Shellder, Staryu, Lombre, Evee.
you can't. you have to trade to get it.
NO you cant but you can in leafgeen
The Pokémon in Sapphire who have the Illuminate ability are Volbeat, Staryu/Starmie and Chinchou/Lanturn.
yes staryu is rare in Sapphire and ruby
How do you catch latios in Pokemon sapphire