If you mean where is Yojimbo, he isn't in a Temple, he is in the Cavern of the Stolen Fayth.

To get here go to the Calmlands and exit north towards Mt Gagazet. (Where you fought Defender X/Z whatever it was).
You will go across a bridge. There is a valley below you. Go down into the valley and there is a cave in front of you. Keep walking towards it until you enter it. Go right to the very back of the cave to find Yojimbo.

I can't remember which part is the Baaj temple right now. *doh*

If you mean the fish that you have to kill with Tidus, Wakka and Rikku underwater, the one that attacked Tidus in the past, well I didn't have a strategy I found it a fairly okay fight. If you can't kill it yet all I recommend is level up more..and if it petrifies you equip stoneproof armour.