Defining Characteristics:  

• Unique colors and patterns
• Diurnal
• Active day gecko
• Excellent display animal

Name: Phelsuma robertmertensi. Known as Robert Merten’s day gecko.

Recommended Enclosure Size: A single animal can be kept in a12x12x18. Pairs have been successfully kept and bred in this size enclosure, although a pair will appreciate an 18x18x24 glass enclosure. A bioactive setup with live plants is strongly recommended for this species; BioBedding is recommended to maintain live plants, springtails, and isopods. Provide plenty of climbing material in the form of cork bark, branches, or bamboo for this arboreal species.  

Temperature: Keep Robert Merten’s day geckos between 75-80 F. A basking spot of around 90 F is also recommended. Temperature should be monitored with a digital thermometer. Night temperatures should not fall below 65 F. Robert Merten’s day geckos should also be provided with a 5.0 or similar strength UVB light.

Humidity: Robert Merten’s day geckos should be provided a humid but well-ventilated setup between 60-70%. Live plants can be added to help stabilize higher humidity as well as provide humid microclimates. Ambient humidity should be monitored with a digital hygrometer. Robert Merten’s day geckos should be misted daily to provide dew on enclosure walls and cage items from which they can drink. A water dish can be provided but is not necessary with regular misting; a water dish will not replace the need to regularly mist the enclosure.

Size: These day geckos reach around 5 inches as adults.

Age: Robert Merten’s day geckos are at least 4 weeks old when sold by Josh’s Frogs, at which time they are well established. It is estimated that these geckos live for 10-15 years in captivity.

Feeding: Robert Merten’s day geckos are omnivores, eating both insects and fruit in the wild. In captivity, they will thrive on a diet of gecko diet mix and feeder insects. Hatchlings and juveniles should be offered ⅛-inch crickets or fruit flies until they are large enough to eat ¼-inch crickets. Providing mounted feeding cups for this arboreal species is recommended. Other appropriately sized feeder insects, like dubia roaches and black soldier fly larvae, can also be offered but need to be provided in a food dish to be accessible. Waxworms, butterworms, and small hornworms make excellent treats, but should only be offered occasionally. Feeder insects should be dusted with a calcium and multivitamin supplement.

Sexing: Robert merten’s day gecko males can be identified by their femoral pores, which will be located between their hind legs.

Color/Pattern: Robert Merten’s day geckos have a light green or blue green body with light brown covering their tail and flanking their sides. A rust-colored interrupted line extends down the back and can be surrounded by a light blue color. The same blue color often accentuates their eyes and nose. 

Social Behavior: Robert Merten’s day geckos are best housed as a pair or solo.

Breeding: Robert Merten’s day gecko females will lay a pair of eggs in a secure location once every 30-40 days. Eggs are loose and usually not adhered to a surface.

Natural Range: These day geckos are endemic to the Comoros, northwest of Madagascar.

History in the Hobby: Endangered in the wild, Robert Merten’s day geckos are not commonly available in the hobby. Their unusual color and pattern compared to other day gecko species makes them a unique addition to any collection.

Links of Interest:

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