Actually, not only is that cook, it could work!
Pistol shrimps have been known to form symbiotic relationships with fish like gobies, and may live to be 20 years old. In a fantasy setting, aquatic elves could use their husbandry skills to form symbiotic relationships with them. Indeed, oversized ones would make ideal companions for non-nomadic aquatic druids or rangers, or possibly even familiars for arcane spellcasters.
Stomatopods like Mantis shrimps are highly intelligent (for crustaceans) and are active hunters. For adventuring aquatic druids, rangers, or paladins, the aggressiveness and fighting instincts of oversized specimens would be ideal. They would also make good stationary guard animals...as long as you only place one in the room- they only get along with others of their species when they're male & females.
And if your druids just happen to know Awaken...