Black and Blue Crested Geckos: What the Genetics Actually Say
Dark and "blue" crested geckos are trending, but they're not separate morphs. Learn the polygenic genetics behind dark crested geckos and why pairings rarely breed true.
# Black and blue crested geckos: what the genetics actually say
A seller listed a "black crested gecko" on MorphMarket last spring for $850. The photos were stunning, a deeply fired-up animal showing near-solid charcoal with a faint iridescent shimmer along the dorsum. The listing said "possible het axanthic" in the genetics field and nothing else. Three breeders I know asked me whether it was worth the price. My honest answer: almost certainly not, and here's why.
So what are dark and "blue" crested geckos, genetically? The short answer is that they are not a morph. There is no proven recessive or incomplete-dominant gene producing "black" or "blue" expression the way Lilly White produces bright white markings. What you're usually looking at is a layered polygenic combination, high melanin, low-saturation base color, particular iridophore reflectivity, plus the dramatic effect of a fully fired-up animal photographed at exactly the right moment.
Published 2026-05-22.
TL;DR
- Dark and "black" crested geckos are not a proven recessive or incomplete-dominant morph, they are polygenic combinations of melanin expression, base color, and firing state.
- "Blue" crested geckos are typically lavender or axanthic animals with cool iridophore reflectivity, not a distinct blue pigment gene.
- Pairing two dark geckos does not reliably produce dark offspring because polygenic traits require multi-generation selection pressure to shift the average.
- Axanthic is the only proven recessive that removes warm pigment, it produces gray, white, and black animals, not blue.
- Buying a "black" or "blue" crested gecko at a premium without documented lineage is a high-risk purchase for any breeding project.
Frequently asked questions
Is there a real black crested gecko morph?
No proven single-gene "black" morph exists in crested geckos. Dark animals are the result of polygenic melanin expression and base color, combined with the fired-up state. The effect can be dramatic in photos but does not breed true like a proven morph such as Lilly White or Axanthic.
Can crested geckos be blue?
There is no proven blue pigment gene in crested geckos. Animals described as "blue" are typically axanthic (a proven recessive that removes yellow and red pigment, leaving gray tones) or lavender-base animals with cool iridophore reflectivity. Neither is a distinct "blue morph."
Will pairing two dark crested geckos produce dark offspring?
It increases the probability across a population, but does not guarantee dark offspring from any individual clutch. Dark coloration is polygenic, controlled by many genes acting additively. Reliable darkening takes multiple generations of consistent selection, not a single pairing.
What is the difference between a dark crested gecko and an axanthic?
A dark crested gecko is a polygenic animal with high melanin expression. An axanthic is a proven recessive morph that removes yellow and red pigment entirely, leaving only gray, white, and black tones regardless of base color genetics. Axanthic requires two gene copies and confirmed lineage documentation.
Is "possible het axanthic" a valid genetics claim for a dark gecko?
No. Visual assessment of het status is never valid for any recessive morph. A dark or gray appearance does not confirm axanthic het status. The only valid documentation is a lineage trace to a proven visual axanthic or a test-breed result.
Why does my crested gecko look black at night but ordinary during the day?
This is the fired-up state. At night, melanin granules spread through the skin, darkening the animal significantly. During the day, those granules clump up and the gecko fires down to a much paler state. This is physiology, not genetics, and it affects every crested gecko regardless of morph.
Canonical URL: https://geckinspect.com/blog/black-blue-crested-gecko-genetics
Geck Inspect is the professional platform for crested gecko
(Correlophus ciliatus) breeders and keepers, collection
management, breeding planning, AI-powered morph identification,
multi-generation lineage tracking, and a verified community.
Enable JavaScript to use the full interactive app, or
create a free account.