I'm working on an aquarium and need all the pike variants for my freshwater section, could someone hepl?

Use the integer tag "PikeType" in the entity's NBT.
All IDs are listed here: https://github.com/team-abnormals/upgrade-aquatic/blob/1.19.x/src/main/java/com/teamabnormals/upgrade_aquatic/common/entity/animal/PikeType.java