Wave Speaker Feat 1
Source Pathfinder Howl of the Wild
Being part fish yourself, you can speak the language of the sea. You can ask questions of, receive answers from, and use the Diplomacy skill with animals that have the amphibious trait, aquatic trait, or a swim Speed, such as fish, crabs, and some seabirds (like penguins). The GM determines which animals count for this ability.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
MerfolkThese aquatic humanoids have an upper body similar to a human and a lower body similar to a fish.