Ahi: ~5 casts
Sailfin: ~35 casts
Striker: ~5 casts
Mahi Mahi: ~35 casts

(225 fishing, +25 fishing-pole, no lure)

Btw, according to blizzard website's fishing guide, all that matters wrt where to fish is the area name above the minimap:

    http://www.worldofwarcraft.com/info/professions/fishing.html
    (search for "Does it matter where I fish?")