Most of this is stated above, but in summary:
Must be level 35 or higher with 225/225 fishing skill before the quest becomes available (used to require level 40, that was changed many patches ago.)
You can't catch any of the fish UNLESS you have the quest, they don't show up if you aren't on the quest. They also are not tradeable, shareable or sellable in the AH, you have to personally catch them with the character who is on the quest.
Reading the quest it tells you where to catch each fish, you HAVE TO be at the place described to catch that fish:
-"Misty Reed Mahi Mahi from the Misty Reed Strand in the Swamp of Sorrows." (if it doesn't say "Misty Reed Strand" on your minimap you won't catch a Mahi Mahi)
-"A Sar'theris Striker from the Sar'theris Strand in Desolace." (if it doesn't say "Sar'theris Strand" on your minimap you won't catch a Striker)
-"Feralas Ahi from the Verdantis River of Feralas." (if it doesn't say "Verdantis River" on your minimap you won't catch an Ahi)
-"Savage Coast Blue Sailfin from the Savage Coast of Stranglethorn Vale." (if it doesn't say just "Savage Coast" on your minimap, this means "Southern" savage coast won't work, you won't catch a Blue Sailfin)
When you get the fish they will show up as an ADDITIONAL fish to the one you normally catch, so say you land a Spotted Yellowtail, above it in the loot window will be the quest fish.
*IF* fish are getting away, you need a better pole and/or lure! If you're landing fish every cast, a lure won't help (for example, Misty Reed is fishable with 225+20 skill) *BUT* if you keep seeing "your fish got away" then you should get a lure. With a Big Iron pole, you can get away with Bright Baubles (+75 skill, 10min duration) but if you have a smaller pole, you should probably grab Aquadynamic Fishing Attractors (+100 skill, but only lasts 5min.)
Each fish is catchable within about a dozen casts *as long as fish aren't getting away and you are in the right spot* so if you are catching something each cast and you are in the right spot you will catch the quest fish.
Must be level 35 or higher with 225/225 fishing skill before the quest becomes available (used to require level 40, that was changed many patches ago.)
You can't catch any of the fish UNLESS you have the quest, they don't show up if you aren't on the quest. They also are not tradeable, shareable or sellable in the AH, you have to personally catch them with the character who is on the quest.
Reading the quest it tells you where to catch each fish, you HAVE TO be at the place described to catch that fish:
-"Misty Reed Mahi Mahi from the Misty Reed Strand in the Swamp of Sorrows." (if it doesn't say "Misty Reed Strand" on your minimap you won't catch a Mahi Mahi)
-"A Sar'theris Striker from the Sar'theris Strand in Desolace." (if it doesn't say "Sar'theris Strand" on your minimap you won't catch a Striker)
-"Feralas Ahi from the Verdantis River of Feralas." (if it doesn't say "Verdantis River" on your minimap you won't catch an Ahi)
-"Savage Coast Blue Sailfin from the Savage Coast of Stranglethorn Vale." (if it doesn't say just "Savage Coast" on your minimap, this means "Southern" savage coast won't work, you won't catch a Blue Sailfin)
When you get the fish they will show up as an ADDITIONAL fish to the one you normally catch, so say you land a Spotted Yellowtail, above it in the loot window will be the quest fish.
*IF* fish are getting away, you need a better pole and/or lure! If you're landing fish every cast, a lure won't help (for example, Misty Reed is fishable with 225+20 skill) *BUT* if you keep seeing "your fish got away" then you should get a lure. With a Big Iron pole, you can get away with Bright Baubles (+75 skill, 10min duration) but if you have a smaller pole, you should probably grab Aquadynamic Fishing Attractors (+100 skill, but only lasts 5min.)
Each fish is catchable within about a dozen casts *as long as fish aren't getting away and you are in the right spot* so if you are catching something each cast and you are in the right spot you will catch the quest fish.