Bluegill
- Appearance: Insectile
- Lavender, six-legged body about 12cm long (TNG: "Conspiracy")
- Long pincers at front (TNG: "Conspiracy")
- Blue gill at rear (TNG: "Conspiracy")
- Lifespan: Indeterminate
- At least 6,000 years (DS9 Short Story: "Sins of the Mother")
- Biological notes
- Capable of infiltrating the nervous systems of most humanoid species, controlling them internally (TNG: "Conspiracy"; DS9 Short Story: "Sins of the Mother")
- Unable to access host body's long-term memory (TNG: "Conspiracy"; DS9 Novel: Mission Gamma: Lesser Evil)
- Species immune to infiltration include Cardassians (DS9 Novel: Mission Gamma: Lesser Evil)
- Descended from symbionts of Trillius Prime (DS9 Short Story: "Sins of the Mother")
- Similar biochemistry, genetic structure as a result (DS9 Novel: Mission Gamma: Lesser Evil)
- DNA similar enough that it can be mistaken for symbiont DNA (DS9 Novel: Mission Gamma: Lesser Evil)
- Neurological connection still mediated by isoboramine (DS9 Novel: Mission Gamma: Lesser Evil)
- Similar biochemistry, genetic structure as a result (DS9 Novel: Mission Gamma: Lesser Evil)
- Capable of infiltrating the nervous systems of most humanoid species, controlling them internally (TNG: "Conspiracy"; DS9 Short Story: "Sins of the Mother")