For different species, fish in different zones and at different times/weather.
With the weak charm you can catch fish level 1 - 5.
With the strong charm you can catch fish level 6 - 10.

• First Catch! – Catch your first fish
  
• Warming up – Catch 100 fish
  
• And a thousand fish later... – Catch 1,000 fish
  
• Smells like fish – Catch 2,500 fish
  
• That was easy – Catch all fish (common)
  
• Starting the collection – Catch 10 different fish species!
  
• Starting the collection (2) – Catch 60 different fish species
  
• Researcher – Catch 100 different fish species
  
• Ichthyology – Complete the fish collection
  ➜ Fish all 140

Use Charms like Shiny Charm or Luck Charm and upgrade your fishing rod to get silver, gold etc. fish.

• A rare fish – Catch 1 fish (rare color)
  
• A silver fish – Catch 1 fish (silver)
  
• Not all that glitters is gold – Catch 1 fish (golden)
  
• From the stars – Catch 1 fish (cosmic)
  ➜ Only possible at Cosmic Sea
  
• The silver moon – Catch 1 halfmoon (silver)
  ➜ Ocean or Moon Cave
  
• The golden dorado – Catch 1 dorado (golden)
  ➜ Beach or Ocean
  
• The true rainbow trout – Catch 1 rainbow trout (rainbow)
  ➜ Magic Forest, Top of the Mountain or Snow Lake
  
• When fish fly.... – Catch a flying fish
  ➜ Forgotten Sea
  
• Fishing the moon – Catch two halfmoon fish at the same time
  ➜ Use the Charm "Twice Charm" and fish at the Ocean or Moon Cave
  
• Exotic fish – Catch all fish (rare color)
  
• On a silver platter – Catch all fish (silver)
  
• Gold, gold, gold! – Catch all fish (gold)
  
• Rainbow hunter – Catch all fish (rainbow)
  
• All the stars – Catch all fish (cosmic)
  ➜ Only possible at Cosmic Sea

Easy achievements, you will get them fast.

• A mysterious cat – Give a fish to the cat
  ➜ drag and drop a fish on the cat
  
• Help from the cat – First cat exploration
  ➜ Wait until the cat is back and take the item
  
• Cleaning waters – Catch 1 trash
  
• Recycle – Recycle one item (recycle trash for one Karma)
  
• A message from the sea – Find one message in a bottle
  ➜ Use a bottle to get the message. You can find bottles while fishing; random event just click on the bottle if you see one
  
• Trader – Trade your first item
  ➜ 3 fishes for one item (Shop ➜ Trade)
  
• Sea explorer – Use a map for the first time

For money, sell as many items, treasures and fishes you can. Use the aquarium for items with a high selling price.
Your rank increase while you're fishing. Just wait for it.

• It's honest work – Earn 100 coins
  
• I can't hold all these coins – Earn 10 000 coins
  
• Wealthy Fisher – Earn 1 000 000 coins
  
• Rank D – Achieve Rank D
  
• Rank A – Achieve Rank A
  
• Rank SSS – Achieve Rank SSS

Upgrade your Boat Level (Shop ➜ Upgrade) to find new places like Snow Lake.
You can find the Cave Entrance & Snow Lake with a level 3 boat and level 3 map.

Visit following places:

• Pond in the forest
  
• Beach (Cat can find it)
  
• Magic Forest (Cat can find it)
  
• Ocean (Buy a boat)
  
• Shining Cave (Map)
  
• Coast (Storm or Map)
  
• Volcano (Map)
  
• South River (Map)
  
• Top of the Mountain (Map)
  
• Snow Lake (Map; Boat Level 3 & Map Level 3)
  
• Moon Cave
  ➜ Opens when you fish in The Cave Entrance with a fishing rod level 8 or higher
  
• Sky Island
  ➜ Only the blessed by the Four Guardians may enter the kingdom hidden among the clouds
  
• Cosmic Sea
  ➜ After you complete the fish collection, you automatically open the place

Finish the quests to get Blessings, Karma and Charms.

• The merchant quest – Complete the first quest of the merchant
  ➜ Village
  
• The pirate quest – Complete the first quest of the pirate
  ➜ Beach
  
• The suspicious catfish quest – Complete the first quest of the suspicious catfish
  ➜ The forgotten Sea
  
• Bridge to adventure – Repair the bridge
  ➜ Bridge to the Island; 3 Wooden Log needed
  
• The statue in the forest – Receive the Guardian’s Blessing
  ➜ Click on the Shrine at Shrine in the Forest
  
• The Guardian of sea – Receive the Guardian’s Blessing
  ➜ Ocean (wait for rain/storm)
  
• The Wise – Receive the Guardian’s Blessing
  ➜ Finish the Quest at the Cave Entrance - you need a fishing rod level 8 or higher
  
• Exotic Items – Complete all quests of the merchant
  ➜ Village (he wants items. Make sure to keep at least one of every item in your inventory)
  
• Arrr! – Complete all quests of the pirate
  ➜ Beach (He wants treasures. Make sure to keep at least one of every treasure in your inventory)
  
• Is this the end of the world? – Complete all quests of the suspicious catfish
  ➜ The forgotten Sea (He wants fishes from specific zones)

You get Karma for finishing quests and recycling trash.
You unlock the Karma Store when you enter The Magic Forest.

• Karma (10) – Earn 10 Karma
  
• Karma (100) – Earn 100 Karma
  
• Karma (500) – Earn 500 Karma

You can buy upgrades by clicking the coin symbol next to the map. Click the tab "upgrades".

• Getting fancy – Upgrade your fishing rod for the first time
  
• Max Fishing Rod Level – Upgrade Fishing Rod Level to max level
  ➜ Max. level is 9
  
• Max Bag – Upgrade Bag to max level
  ➜ Max. level is 28
  
• Max Auto-fishing speed – Upgrade Auto-fishing speed to max level
  ➜ Max. level is 50
  
• Max Auto-Sell – Upgrade Auto-Sell to max level
  ➜ Max. level is 15
  
• Nice day for fishing! – Achieve +100 luck
  ➜ Increase your luck with charms (luck charm or perseverance charm) and karma
  
• Max Luck – Upgrade Luck to max level
  ➜ Increase your luck with charms and karma. You get the achievement if your luck is above 150, but the max. luck is 190
  
• Max Fish Quality – Upgrade Fish Quality to max level
  ➜ Max. level is 15
  
• Max Cat Level – Upgrade Cat Level to max level
  ➜ Max. level is 9

You get charms when you're blessed. Unlock new zones and finish the quests. Some charms need to be crafted.

• Lucky charm! – Get your first charm
  
• More charms! – Craft your first charm
  
• Very charming! – Collect all charms
  ➜ 20 total, you need to craft/unlock all of them

Put a fish in your aquarium and you get the item the fish produces.

• The aquarium – Buy your first aquarium
  
• Friendship – Get an item from a fish in an aquarium
  ➜ Wait a few minutes and click on the item
  
• Max Aquarium Friendship – Upgrade Aquarium Friendship to max level
  ➜ Max. level is 11
  
• Too many fish on my desktop! – Buy all aquariums
  ➜ You can buy 10 aquariums
  
• Playing fetch – Receive a stick from a fish in an aquarium
  ➜ dogfish or puppy fish
  
• Love or hate? – Receive poison from a fish in an aquarium
  ➜ blowfish, lionfish or snakehead
  
• Coffee shop – Have an aquarium with fish that gives you donut, cookie and coffee
  ➜ Donut: Muskie, Tripletail, Tuffy
  ➜ Cookie: Polka Dot, Flounder, Lingcod
  ➜ Coffee: Catfish, Black Crappie

You need a level 10 fishing rod to catch any of these legendary fish.

• The legend of the full moon – Catch 1 lunar moth fish
  ➜ Go to the Moon Cave at night to catch this final legendary fish.
  
• The greedy fish
  ➜ To catch the Greedy Fish, you must have treasure worth 35,000 gold in your inventory. Then, go fishing in the Shining Cave.
  
• The ancient fish
  ➜ Have all three fossils (Skull, Fang and Tail) in your inventory. Then, fish in the Snow Lake.
  
• Emerald Dragon
  ➜ Keep both the Ruby Snapper and the Sapphire Ram in your inventory, then fish in the Sky Island.

• Secrets of the Sea – Complete the notes collection
  ➜ open bottles until you find all 12 notes
  
• Clues to a legend – Find clues about a legendary fish
  ➜ find the message "The legend of the full moon" in a bottle
  
• Friend of the fish – Complete the item collection
  ➜ find all 44 items
  
• A true treasure hunter – Complete the treasure collection
  ➜ find all 40 treasures
  
• Mystery egg – Find the mystery egg
  ➜ Top of the mountain, click on the egg
  
• From the ashes – Return the mystery egg
  ➜ Vulcano
  
• A hot cave – Complete the shrine outside the volcano
  
• Shining bag – Have diamond, emerald, ruby, sapphire, pearl, topaz and opal in your inventory
  ➜ Mark the gems as favourite (heart symbol) so you don't sell them with autosell
  
• Greedy fisher! – Carry items and treasures worth 35 000 coins in your bag
  ➜ Increase the selling price with karma and have high level treasures in your inventory
  
• Archeologist – Carry all three fossils in your bag
  ➜ Your cat can find the fossils or you can fish them at the Snow Lake
  
• A cozy rainy day – Carry bread and coffee in your bag on a rainy day
  
• Legendary Treasure Hunter – Catch 1 legendary treasure
  ➜ Fish with a rod lvl 9+. You can find one specific legendary item at every zone
  
• A thousand year sleep – Find the lost guardian
  ➜ You need fishing rod level 8 and you need to fish at the Cave Entrance