In survival mode:

Fish Fighter Affronters (LV.1) may appear in the enchanting Taichung

Fish Fighter Epipice (LV.1-3) may encounter

Fish Fighter Epipice (LV.1-5) may appear in the dungeon/Mochi City/Village box:

Dungeon box: Fish Fighter enchantment of LV.3-5 may fall

Abandoned mine/Mochi City/Shipbuilding: Fish Fighter enchantment that may drop LV.4-5

Village box: Fish Fighter enchantment of LV.1-3 may fall

Fish Fighter's enchantment (LV.1-5) may appear in the warrior of zombies/drowning/guards/Guardians:

Zombie: May fall LV.1-3 Fish Fighter

Drowning: It may drop LV.2-4 Fish Fighter

Guardian: Fish Fighter enchantment that may drop LV.4-5

Far Guardian: Fish Fighter's enchantment of LV.5 must be dropped

In the creation mode:

It is impossible to obtain the FISH FIGHTER enchantment higher than Level 1, but you can kill the above monsters by /Summon Elder_Defender, etc.