Dire Lionfish

Charge. If it moves 30'+ straight to foe and hits with Headbutt attack on same turn target takes an extra 9 (2d8) piercing damage.

Coral Camouflage. The lionfish has advantage on Dex (Stealth) checks made to hide in underwater terrain that includes plant life or coral reefs.

Envenomed Spines. A creature that touches lionfish or hits it with melee attack while within 5 ft. of it: 7 (2d6) poison.

Poison Affinity. Advantage on saves vs. being poisoned.

Water Breathing. Can breathe only underwater.

Multiattack. One Bite attack and one Headbutt attack.

Bite. Melee Weapon Attack: +6 to hit, 5 ft., one target, 14 (2d10+3) piercing damage.

Headbutt. Melee Weapon Attack: +6 to hit, 5 ft., one target, 12 (2d8+3) bludgeoning damage + 7 (2d6) poison.

Forceful Spit (Recharge 4-6). Launches a stream of pessurized water from its mouth in a 30' line that is 5 ft. wide Each creature in that line: 21 (6d6) bludgeoning damage and is pushed up to 20' away from the lionfish and is knocked prone (DC 14 Dex half damage and is pushed up to 10 ft. away from the lionfish and isn't knocked prone.)