For describing silhouettes -
There's the standard fish shape. This comes in Small Fish (SF), Medium Fish (MF), and Large Fish (LF).
There's the "dragon" shape, with the same sizing and abbreviations. SD, MD, LD.
And the same for the "shark" shape. SS, MS, LS.

Some "boss" fish glow a purply pink. I call these Purple. I like to keep it simple.
The metal fish have this kinda metal glimmer white shimmer thing. However it can be hard to spot, so if you're going for a metal fish, I recommend just hitting every silhouette of the right type. You'll have to do a lot of forcing respawns anyway.

If you have trouble understanding the guide, just go into the game and catch an easy early fish, then check what its' silhouette was called. I hope this helped!

(also, I have not finished the game. if there are more types of silhouette, I'll add them.)

The achievement "Just Disappear!" is permanently missable. To get it, do NOT do the dungeon to open up the gate in Lanome Island. Instead, go to Volkanios, and try to enter. You'll be refused entry because you don't have a card, and a shady guy will offer to get you a membership card if you beat a dungeon for him. You can do this dungeon before beating Lanome, it doesn't glitch out story progression. Do that dungeon, and you will get the warp wand. Come back to Lanome and warp past the closed gate.

If you're having trouble with the Metal fish, the Venom Rod's effect, hilariously, works on them. It's an AFK catch as long as you don't mind losing some HP.

For the Ghost boss fight, you have to actually hit and kill all of the fakes. They should go down in about four hits. You do NOT go around hitting all of them only once to find the real one, and you do NOT just dodge until they fade away on their own. You kill em. I don't wanna admit how long I spent dodging.

1. Crcarp - MF - 14
   
2. Catfish - MF - 28
   
3. Hercrab - SF - 15
   
4. Stareye - SF - 18
   
5. Horsemac - MF - 36
   
6. Boltjelly - SF - 18
   
7. Tunny - Purple MF - 286
   
8. Balloon - MF - 32
   
9. Percrab - SF - 16
   
10. Pacific - MF - 64
    
11. Skullpus - MF - 72
    
12. Drillsquid - MF - 68
    
13. Ballwhale - Purple MF - 240
    
14. Peony - MF - 66
    
15. Panda - MF - 57
    
16. Ogreflog - MF - 52
    
17. Scallop - SF - 28
    
18. Flapjack (purple clam) - SF - 30
    
19. Flapjack (small octopus) - SF - 52 (I don't know why they have the same name.)
    
20. Seadragon - SD - 89
    
21. Fishslime - MF (after boss battle, appears w/o purple) - 258
    
22. Monkfish - MF - 75
    
23. Nepeam - SF - 64
    
24. Lunalion - MF - 74
    
25. Shadow - MF - 54
    
26. Muddy - Purple LF - 410
    
27. Goldenfrog - Gold MF - 10
    
28. UMA - MF - 28
    
29. Gigademer - MF - 30
    
30. Boltarowana - MF - 139
    
31. Bonescorp - MF - 68
    
32. Dogfish - MF - 224
    
33. Soilcraw - MF - 248
    
34. Moss - MF - 212
    
35. Rockbream - MF - 308
    
36. Gourde - MF - 158
    
37. Gigaturtle - Purple LF - 1,080
    
38. Stormville - MF - 720
    
39. Megadelon - Purple LS - 1,820
    
40. Sharkevil - MS - 725
    
41. Sharkgear - MS - 611
    
42. Flameslug - SF - 340
    
43. Flamedance - MF - 412
    
44. Flamehorse - MF - 386
    
45. Flamemanta - MF - 512
    
46. Crocoflame - MS - 811
    
47. Flamedragon - Purple MD - 872
    
48. Flamemoray - Purple LD - 1,180
    
49. Iceslug - SF - 340
    
50. Icehorse - MF - 386
    
51. Icedance - MF - 412
    
52. Icedragon - Purple MD - 872
    
53. Icedolphin - MS - 738
    
54. Icenarwhal - MF - 685
    
55. Iceburn - Purple LF - 2,020
    
56. Crabbalkan - Purple MF - 232
    
57. Metlkan - Purple MF - 256
    
58. Blade - Purple LS - 2,140
    
59. Lightning - MF - 185
    
60. Darkness - MF - 202
    
61. Ghost - Purple MF - 1,284
    
62. Balkan - MF - 734
    
63. Swordon - MS - 557
    
64. Elmer - MF - 148
    
65. Rantle - SF - 582
    
66. Silva - SF - 612
    
67. Warlobs - Purple LF - 1,520 (swords)
    
68. Armordine - Purple MD - 162
    
69. Arts - MF - 174
    
70. Rapier - MF - 202
    
71. Laplace - Purple LS - 2,680 (can appear in all sea areas once unlocked, I found one on Rimul Beach)
    
72. Entropy - Purple LS - 2,840 (same as above, I found one on Cossack)
    
73. Battlegon - MF - 697
    
74. Cobaltone - MF - 712
    
75. Rapun - MF - 224
    
76. Ironhead - MF - 148
    
77. Needle - MF - 191
    
78. Daitarl - Purple MD - 346
    
79. Angelnake - MF - 549
    
80. Neshiram - Purple MD - 382
    
81. Mosalgan - MF - 191
    
82. Papal - MF - 182
    
83. Octoborg - MF - 178
    
84. Siren - Purple MF - 215
    
85. Skyfish - MF - 448
    
86. Killerscope - MF - 224
    
87. Endclub - MF - 580
    
88. Pottal - Purple MF - 611
    
89. Elekidrago - Purple MD - 918
    
90. Noah - MF - 742
    
91. Leviathan - MD - 768
    
92. Sheeragnarp - MF - 640
    
93. Venom - Purple MD - 634
    
94. Chainsol - MS - 520
    
95. Bryunak - Purple MD - 985
    
96. Mogdrill - MF - 268
    
97. Chakurcha - Purple MF - 860
    
98. Goldarmeel - MF - 662
    
99. Shenlong - Purple MD - 972
    
100. Puchimetal - Metal Glimmer SF - 7 (you only deal 1 dmg per hit)
     
101. Fullmetal - Metal Glimmer MF - 12 (same as above)
     
102. Granmetal - Metal Glimmer LF - 18 (same as above)
     
103. God Frog - Golden LF - 21 (same as above)
     
104. Black Dragon - only in story, exempt - variable