Both are great snakes, if you have the means to keep them. I keep both of them. I currently keep 2,1 Spilotes pullatus (Tiger ratsnake) and 1,2 Gonyosoma oxycephalum (red tail green ratsnake). They don’t differ much in their basic needs, both need high temperatures and humidity and both like to climb.
So if you want to decide which one you want to keep, ask yourself how much space you are able to provide and how big you budget for future power expenses will be.
Spilotes and Gonyosoma are both large and active snakes. They will use all the space you can provide. In general, Spilotes will need a (much) larger enclosure as Gonyosoma. In my experience both species will be more active in larger enclosures, keeping them under minimum conditions will deprive you of a lot of fun watching the full range of their behavior.
- Spilotes will easily reach 10 ft (3 m) in length. Both of my males are currently about 2.8 m (>9 ft), my female is ca. 2.5 m (>8 ft) and they are still growing.
- Gonyosoma is reported to reach 2.4 m (8 ft), but I never had a snake longer than 1.8 m (6 ft.)
So a good enclosure size for Spilotes would be something about 7 x 3 x 5 ft (200 x 90 x 150 cm) (length x depth x height), whereas for Gonyosoma it would be 5 x 2 (3) x 5 ft (150 x 60 (90) x 150 cm).
Both need a lot of branches, some hiding places and you can provide life plants, which will help to maintain the humidity. Spilotes will sometimes stay on the ground, Gonyosoma will stay in the branches most of the time.
For both snakes I use only lamps for heating, UTH is useless for an enclosure of this height. For my large Spilotes enclosure I use a total of 210 W of lighting for 14 hours a day (so you can do the math about the amount of money you might need…).
Are the snakes you were offered wild caught or captive bread? I have no experience with WC, CB Spilotes are in easy to handle in most cases, in my experience Gonyosoma is more unpredictable and might try to bite you more often – on the other hand a bite from a large Spilotes hurts much more
…
So if this is your first large arboreal Colubrid and you have the space I would suggest Gonyosoma, if you have even more space and more experience get Spilotes.
Please feel free to ask any question you might have...
Roman