Blood Smell. An Acid Shark may by smelling be able to find any damaged creature within 600 m (1968 ft) and tell exactly how much HP said creature has. This only works against damaged creatures with a functioning blood circulation (not spirits, elementals, undead, plants, constructs or creatures with alien anatomy).

Weak Belly. While the normal skin of an acid shark is resistant to bludgeoning, slashing and piercing damage this doesn't apply to the underbelly, which is instead vulnerable to all physical attacks. 

Gaze of Death. If the acid shark is able to make eye-contact with an enemy, said creature take 4D12 + 30 acid damage when the bile in their stomach start melting through. Doesn't work against creature's with no stomach. 

Devour. If beat a creature on a dex check and a str check the acid shark may devour the creature, dealing 40 acid damage, 8D6 piercing damage and 8D6 bludgeoning damage.

Bite. Melee Weapon Attack: +8 to hit, reach 1,5 m (5 ft), 1 target. Hit: 5D12 + 15 piercing damage & 3D8 + 6 bludgeoning damage.

Tentacle Strike. Melee Weapon Attack: +8 to hit, reach 5 m (16 ft), 3 targets. Hit: 5D8 bludgeoning damage.

Acid Spit. Ranged Weapon Attack: +6 to hit, range 20 m (66 ft), 1 target. Hit: 2D10 acid damage.

Water-Blow. Ranged Weapon Attack: +8 to hit, range 50 m (164 ft), 1 target. Hit: 3D8 bludgeoning damage, target get pushed back 5 m (16 ft).

Head But. At will the acid shark may but it's head into any creature within 3 m (10 ft) dealing 2D10 bludgeoning damage. The creature has advantage in saving throw. 

Bump. After being attacked the Acid shark may roll strength and if beat the targeted enemies saving throw deal 2D8 bludgeoning damage.