Emerald eels

Emerald eels are a species of eel within Mireiya named after their distinct colouration. When happy or trying to attract a mate, said eels glow, producing a beautiful visual effect within the nearby water. As such, they're a popular inclusion within temples to Mistral, where they're kept in small pools where their glow encompasses the entire water.
Appearance
An emerald green as their namesake, a fully grown emerald eel is on average 1.5 metres in length. Their fins are a pale, translucent white as standard, but when glowing they light up an even brighter green than that of the main body.
Diet & Behaviour
Emerald eels are very peaceful by nature, subsiding on vegetation & being actively curious towards other lifeforms outside their natural predators. The eels generally travel in sizeable schools, working as a unit to avoid predators. When a predator approaches the school, the eels will scatter in different directions. After a while, the eels not being chased will double back and attempt to get in front of the predator's eyes at which point they'll flash brightly before swimming off, hoping to temporarily blind & daze the predator, allowing the school to escape. This process repeats until either the predator leaves in frustration or successfully manages to get its fill of eels.