Salamander, Titan (CR 2)

Large Animal (Aquatic)
Alignment: Always neutral
Initiative: +1 (Dex); Senses: low-light vision, Listen +1, and Spot +4

AC: 13 (-1 size, +1 Dex, +3 natural), touch 10, flat-footed 12
Hit Dice: 4d8+12 (30 hp)
Fort +7, Ref +5, Will +0
Speed: 40 ft., swim 30 ft.
Space: 10 ft./5 ft.
Base Attack +3; Grapple +11
Attack: Bite +6 melee
Full Attack: Bite +6 melee
Damage: Bite 1d8+6 plus 1d6 acid
Special Attacks/Actions: Acidic bite
Abilities: Str 19, Dex 12, Con 16, Int 1, Wis 8, Cha 6
Special Qualities:
Feats: Alertness; Endurance
Skills: Listen +1, Move Silently +5, Spot +4, and Swim +12
Advancement: 5-12 HD (Huge)
Climate/Terrain: Temperate and warm marsh
Organization: Solitary or pair
Treasure/Possessions: None

Source: Web

Acidic Bite (Ex): The titan salamander's saliva is caustic and inflicts 1d6 points of additional acid damage on a successful bite attack.

Wild titan salamanders are nocturnal and consider any creature of small size as potential food. If they encounter anything larger, they prefer to flee. If forced to fight, they try to move the combat into a water source and use their bite to best effect.

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.