GFP

What GFP looks like

Carries the Green Fluorescent Protein transgene (GFP+). Under normal visible light, GFP axolotls appear identical to their non-GFP counterparts of the same base morph. Under blue or ultraviolet light, GFP-expressing tissues fluoresce bright green, with gills and eyes often showing the most intense fluorescence. GFP is dominant. One copy produces visible fluorescence. Can be combined with any base color morph. GFP on a leucistic or albino base is the most visually dramatic combination because the green fluorescence contrasts strongly against the pale body. Note: GFP is a transgene of laboratory origin (Aequorea victoria jellyfish), not a natural axolotl mutation.

Green Fluorescent Protein transgene. GFP-positive axolotls express a fluorescent protein originally derived from the jellyfish Aequorea victoria. Under normal visible light, GFP axolotls appear identical to their non-GFP counterparts. Under blue or ultraviolet light, GFP-expressing tissues fluoresce bright green. The transgene segregates as a dominant trait: one copy (hemizygous/heterozygous) produces visible fluorescence. GFP can be combined with any base color morph. The fluorescence is visible in all chromatophore backgrounds, though it is most dramatic in lighter morphs (leucistic, albino) where the green glow contrasts against the pale body.

How to identify it: GFP+: Under normal light, indistinguishable from non-GFP animals of the same morph. Under UV/blue light, fluoresces bright green throughout the body, with gills and eyes often showing the strongest fluorescence. Intensity varies between individuals. GFP-: No fluorescence under UV light. Confirm GFP status with a UV/blue light source. Visual inspection under normal lighting is unreliable.

How GFP is inherited

GFP follows a dominant inheritance pattern, carried on the GFP (Green Fluorescent Protein) allele (locus GFP).

Combo morphs with GFP

• Firefly

  Leucistic (d/d) combined with GFP transgene. A white-bodied axolotl that fluoresces bright green under UV or blue light. The pale leucistic body provides maximum contrast for the green fluorescence, making this one of the most visually dramatic axolotl morphs. Note on naming: The term "Firefly" was originally coined by Lloyd Strohl II in 2016 for embryonic graft chimeras (dark body with GFP-leucistic tail), which are NOT genetically heritable. In common hobby usage, "Firefly" has broadened to describe any leucistic + GFP axolotl. This combo_morph entry represents the heritable leucistic + GFP genotype, not the chimeric graft.