BetonQuest 2.0

https://betonquest.org/RELEASE/

objective:
  <objective name>: customfishing_group <fish group name> <amount to be catched>
  <objective name>: customfishing_loot <fish_id> <amount to be catched>

Example:

objectives:
  catchPoundFish: "customfishing_group pound 5"

This mean that you have to catch 5 fish in a "pound" group

objectives:
  catchTunaFish: "customfishing_loot tuna_fish 3"

This mean that you have to catch 3 "tuna_fish"

(Thanks @Rastart_ for providing the example)