Northrend Angler

Borean Man O' War School - Borean Tundra (anywhere along the coast)
Deep Sea Monsterbelly School - Borean Tundra, Dragoblight, Howling Fjord (around Icebergs in the Frozen Sea)
Dragonfin Angelfish School - Dragonblight (Lake Indu'le)
Fangtooth Herring School - Howling Fjord (rivers and lakes, not coast)
Glacial Salmon School - Grizzly Hills (rivers and lakes, not coast)
Glassfin Minnow School - Crystalsong Forest
Imperial Manta Ray School - Northrend (general Northrend fish, found off any coast, not in lakes or rivers)
Moonglow Cuttlefish School - Borean Tundra, Dragonblight, Howling Fjord (around Icebergs in the Frozen Sea)
Musselback Sculpin School - Borean Tundra (Lake Kum'uya)
Nettlefish School - Sholazar Basin (rivers and lakes, not coast)

Happy Fishing!

In order of zones: Borean Tundra - Borean Man O' War School - (anywhere along the coast) Borean Tundra - Musselback Sculpin School - (Lake Kum'uya) Dragonblight - Dragonfin Angelfish School - (Lake Indu'le) Crystalsong Forest - Glassfin Minnow School - (anywhere in the zone) Grizzly Hills - Glacial Salmon School - (rivers and lakes, not coast) Howling Fjord - Fangtooth Herring School - (rivers and lakes, not coast) Sholazar Basin - Nettlefish School - (rivers and lakes, not coast) Borean Tundra, Dragonblight, Howling Fjord - Dee

Here, there are a list of maps of where to go to get your fishes.
Glassfin Minnow School will be found ->Crystalsong Forest
Deep Sea Monsterbelly School, Dragonfin Angelfish School & Moonglow Cuttlefish School will be found ->
[url=http://www.wowhead.com/?maps=65:598807586809569800551763528749621807646800672809691827702836727842752834748813779829774815597833584827591856602871363813348800331792327813335834356840391669404660414669417691406697393691378809396807415819435834455803475788494772510763803829836834879831892866860819794776804757829737860751878778900798927768922815913860312792295776279759277733275708256691242693225683217669199671187673178658275693402790420782437796362780379788594786617788]Dragonblight
Glacial Salmon School will be found ->[url=http://www.wowhead.com/?maps=394:542520549506559514304460303481301502291528300543287570291584277601270631269648275660288642297609290671282691265712269700266675255708247728239745230757224768209790198801202823252749246774239792238815103411120403134401148394161390150407174403187411203409213415237415246407259403272401286407294417300429304415296403306396321398335386341365353359353345357328367326374332382324392314402318411330418341400349388343376361376372375390370411357400366390356419347427334433321440312446534497534479534464544440547427545411538394612516619497628516641522655535664549673563680580689598685479683460696456703442708427716411734417751407765401770433756440739446718462704464731458]Grizzly Hills
Deep Sea Monsterbelly School, Fangtooth Herring School & Moonglow Cuttlefish School will be found ->[url=http://www.wowhead.com/?maps=495:326262334262345248351231365229375227402223387236404196405182419168432182448182457200439221427227413225423256424279423300424330426347424366406366423388435398466401452403477396500384514378524366546353485407497403511398524392533384542374546392556396554370554335568328581333606357594335603318617310611341620332607378608398610411534442534469544477529506531528533547537563542576568578579574590572601559606532611506615487626504630530633553639580645603637621629642617648608631610607604590623673616689612700608712623293636264642238641223628203613184626180643172656196676194669217650219648366656392658413]Howling Fjord
Borean Man O' War School, Deep Sea Monsterbelly School, Moonglow Cuttlefish School & Musselback Sculpin School will be found ->[url=http://www.wowhead.com/?maps=3537:211539234532887547873570889578922572922543915528814644804669801683777685762656787636796662718658702671715631739611740642733666727695654638626613650584676600652539704576656504702520726537765539787530821500847489869485901450928436612652620681601710564759549751531765559786579823594807597844608885602910571902545899554939519965479949498908510887528875542860545833510790496800471809455813435801427784410776396768371759344757378807374827393825378869362858358883374895419924436930443910452883475883490877503867450846443858462856317763306768303747310718329739343741356714345699323681316664300662288708297712295726275737266739275749270700269683255669251691257706242631229623217609211584224568231582244603239504230481216487205499247483300543296582292605292633292520292489308477323462332454351438375429393415388378402366414347428337432320452302461289463264463244457221450209443176433153424137408126404089404075379089370106379110392108395091384071367073356083365091522464516475502473501458490448488431502427516423528425529448]Borean Tundra
Nettlefish School will be found ->[url=http://www.wowhead.com/?maps=3711:341299347316348335354357347372345390351401362415376415389409400417413433428444444450454452454434437425427407420392392359404378397337380357371359454491465502476499488510490532490551494572485623471633471656484683488714477732459749443757446786454811476823484838494852509858528858553858569858585854580838496823505833509631527627547633554640562640575636572621562611542619568588577574579557580539581528586516593500604499598518619518613504632491645473652469665471676454677440654493647497655506664502645518637526591636598648603660610667624681638683651673664669673666685666699654709660722652727633738638738660729669712675448617414617435623424621431603423594414603404613392619382609366609361631379623384638400638445733306642317640331634326603314598303598329621299611295631283625268629251621240619229609242601253600260611275611]Sholazar Basin
Imperial Manta Ray School will be found in any of these maps that have the coasts marked, its a fish that can be found anywhere on the coast.
I'd start in Sholazar Basin and go through Borean Tundra, Dragonblight, Grizzly Hills, Howling Fjord, Hearthstone to dalaran and go to Crystalsong Forest. Then you should be done, I think that would be the fastest way, that's how I did it and ofc with a 280% flying mount it took me about half an hour to get the achievement done.
Good luck and hopefully you'll be able to get more achievements done on your way to Northrend Angler.

Brazz - Feral Druid
Hellscream.