 | Flat Fins | The most common fin type seen on Siren, lacking innate defences, but built for speed and easy escape. |
 | Frill Fins | Uncommon, but beautiful, frill fins may not offer defence, but it seems to be unneeded as those possessing this mutation simply captivate enemies with their beauty. |
 | Frilled Lionfish | Frilled lionfish is rare, offering slightly less protection than other lionfish mutations as it is more decorative than threatening, it may still be considered deadly as the tail of the Siren possesses the trademark poison barbs. One powerful swipe of the tail could incapacitate or even kill an enemy despite the delicate appearance of this mutation. |
 | Ghostly Glow | An Event-Only Mutation that rarely appears amongst the Siren, giving them the appearance of otherworldly luminescence. It enshrouds their entire body, sometimes giving the Siren's body the ghostly illusion of transparency. In even rarer instances, their fins also seem to radiate motes of light that surround them like stars. |
| Phosphorescence | A rare mutation where parts of the siren's body, markings, or eyes emit a strange glow as if from within. This mutation is not the same as ghostly glow. (Ghostly glow lends the siren transparent elements as well as a glow, and is full body rather than partial) |
 | Sailfish | Uncommonly seen among Siren, the Sailfish fin-type offers a balanced mix of both defence and speed. Streamlined for moving through the water with efficiency and tipped with sharp spines, this mutation is seen amongst the best hunters of a pod. |
 | Sharp Lionfish | Lionfish is rare amongst Siren, but perhaps that is a good thing, for its deadly barbs and spines are tipped with poison that can be injected into an enemy at will. Even when the poison is unused, a conflict with the razor sharp spines alone can be deadly. |
 | Wave Fins | One of the most common fin types seen on Siren, lacking innate defences, but built for speed and beauty. |
