Bichir (CR 4)

Large Animal (Aquatic)
Alignment: Always neutral
Initiative: +2 (Dex); Senses: underwater senses and Listen +5

AC: 14 (-1 size, +2 Dex, +3 natural), touch 11, flat-footed 12
Hit Dice: 5d8+5 (27 hp)
Fort +6, Ref +7, Will +3
Speed: 20 ft. swim 40 ft.
Space: 5 ft./10 ft.
Base Attack +3; Grapple +2
Attack: Bite +5 melee
Full Attack: Bite +5 melee
Damage: bite 3d4+3
Special Attacks/Actions: Entangle
Abilities: Str 17, Dex 15, Con 13, Int 1, Wis 12, Cha 2
Special Qualities: Magic resistance 30%, spell-like abilities (see text), water breathing
Skills: Hide +2, Listen +5, and Search +3
Advancement: 2-4 HD (Medium), 5-7 HD (Large)
Climate/Terrain: Temperate and tropical swamp
Organization: Solitary (1-4) or School
Treasure/Possessions: Standard

Source: Converted

When hunting on land, a bichir moves forward slowly, much as a snake does, until it reaches a point where it can strike at its prey. As it moves, it pauses frequently to sniff around before continuing onward.

When it strikes, the bichir lunges forward to snap with its powerful jaws and sharp teeth. Despite the size of its maw, the bichir never swallows its prey whole.

If confronted by a creature that it cannot overcome or if it is having difficulty slaying its victim, the bichir can cast an entangle spell. This spell can be used as many as six times per day and has a range of 60 yards; it is otherwise identical to the priest's spell of the same name. The bichir can make use of the entangle spell to flee from danger or to aid it in defeating a creature more powerful than itself.

Although the bichir has a natural resistance to magical spells and their effects, it greatly fears such attacks. When confronted by creatures that clearly have magical abilities, the bichir will either flee or, if that is impossible, attempt to ambush them.

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.