Here's a dolphin one, the delphinial:
Guardinal, Delphinial
Large Outsider
Hit Dice: 16d8+80 (152 hp)
Initiative: +12 (+4 Improved Initiative, +8 Dex)
Speed: 20 ft., swim 70 ft.
AC: 22 (+5 natural, +8 Dex, -1 size), touch 17, flat-footed 14
Attacks: Longsword +1 +24 melee, headbutt +19 melee; or headbutt +24 melee, tail slap +19 melee
Damage: Longsword +1 1d8+8; headbutt 2d6+7 (primary) or 2d6+3 (secondary); tail slap 1d6+3
Face/Reach: 5 ft. by 5 ft./5 ft.
Special Attacks: Spell-like abilities, weapons of power
Special Qualities: DR 5/silver, SR 20, outsider traits
Saves: Fort +15, Ref +18, Will +13
Abilities: Str 24, Dex 27, Con 21, Int 14, Wis 17, Cha 18
Skills: Spot +21, Listen +23*, Swim +35, Diplomacy +18, Sense Motive +17, Intimidate +18, Handle Animal +22, Craft (weaponsmithing) +22, Perform (harp) +18, Kniowledge (the planes) +20
Feats: Improved Grapple, Improved Initiative, Improved Unarmed Strike, Run, Skill Focus (Listen, Swim).
Climate/Terrain: Any aquatic
Organization: Solitary, pair, pod (3-5), or sending (4-6 plus 1-10 porpoises and 50% chance of 1-4 merfolk)
Challenge Rating: 10
Treasure: None
Alignment: Always neutral good
Advancement: 17-48 HD (Large)
A delphinial is a guardinal that protects the waters. Usually, they swim alone or in pairs. When preparing for a challenging mission or battle, they form a pod; when a foe is beyond even a pod, another member joins, forming a sending. Sendings attract porpoise followers and, sometimes, merfolk, forming a powerful battle unit beyond most creatures. The only known case when an entire sending is known to have been slain was when the sending was sent to dispatch Areven’efs the Consuming Flame, a balor.
COMBAT
Delphinials use ice storm to soften up foes before closing.
Spell-Like Abilities: At will: dancing lights, detect evil, detect magic, ghost sound, light, ray of frost, read magic; 3/day – cone of cold, fly, ice storm.
Weapons of Power: Though a longsword +1 is listed in the stat block, delphinials may carry any +1, +1 frost or shocking, or +2 weapon.