How's this:
Icetail Swarm
Diminutive Magical Beast (Aquatic, Cold, Swarm)
Hit Dice: 5d10 (27 hp)
Initiative: +2
Speed: 5 ft. (1 square), swim 20 ft.
Armor Class: 14 (+4 size), touch 14, flat-footed 14
Base Attack/Grapple: +5/—
Attack: Swarm (1d6 plus 2d6 cold)
Full Attack: Swarm (1d6 plus 2d6 cold)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction, freezing touch, hold breath, poison
Special Qualities: Darkvision 60 ft., immunity to cold and weapon damage, low-light vision, vulnerability to fire
Saves: Fort +4, Ref +4, Will +2
Abilities: Str 2, Dex 11, Con 11, Int 1, Wis 12, Cha 2
Skills: Hide +20, Listen +7, Spot +7, Swim +4
Feats: Alertness, Endurance
Environment: Cold aquatic
Organization: Solitary or kettle (2-4 swarms)
Challenge Rating: 3
Treasure: None
Alignment: Always neutral
Advancement: —
Level Adjustment: —
This creature resembles a fish skeleton with a few shreds of bluish tissue hanging from its ribs. Closer inspection, however, reveals the creature's body, head, fins, and tail, are all as transparent as glass.
Icetails get their name from the bitter cold of their bodies. These coldwater fish subsist on waste matter, plankton, or whatever other organic matter they can scavenge. Icetails may be cooked and eaten (or eaten raw, though their uncooked flesh is extremely bitter), but if not thoroughly cooked for at least six hours, the eater risks extreme indigestion.
Icetails normally only gather in swarms to mate and lay eggs. Such swarms can be dangerous, since the icetails may attack intruders to protect their eggs and breeding partners. Icetail swarms are most common in glacial kettles (a hole ground out by a receding glacier and filled with meltwater; forming a shallow lake, swamp or bog which makes an excellent habitat for icetail spawn).
An icetail is between 6 inches and 1 foot long and weighs up to a pound.
COMBAT
Icetail swarms are nonaggressive, but will attack if injured or threatened.
Distraction (Ex): Any living creature that begins its turn with an icetail swarm in its space must succeed on a DC 12 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based.
Freezing Touch (Su): An icetail swarm's attack generates a burst of extreme cold which does 2d6 points of cold damage. Creatures hitting an icetail with natural weapons or unarmed attacks take cold damage as though hit by the fish's attack.
Hold Breath (Ex): An icetail swarm can hold its breath by storing water in its mouth and gills. It may do so for a number of rounds equal to 6 times its Constitution score. If out of water beyond that time, it risks suffocating (refer to the drowning rules). For a typical icetail, this is 66 rounds, or over 6 minutes.
Poison (Ex): Any creature that bites or otherwise consumes an icetail is exposed to its poisonous flesh. Fort DC 10, primary damage sickened for 1d3 hours, secondary damage sickened for 2d12 hours. The save DC is Dexterity-based.
Skills: Icetail swarms have a +8 racial bonus to Hide checks due to their transparent flesh. An icetail has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.
In the Realms
Icetails are found primarily in the oceans and rivers of the Great Glacier.
EDIT: 6xCon is fine for the duration.
