this is what i found out on the garden eels.....
Minimum Tank Size: 100 gallons
Care Level: Expert Only
Tank Conditions: 72-78°F; sg 1.020-1.025; pH 8.1-8.4; dKH 8-12
Max. Size In Aquarium: Up to 1' 2"
Color Form: Black, Turquoise
Temperament: Semi-aggressive
Reef Compatible: With Caution
Diet: Carnivore
Compatibility: View Chart
Origin: Indo-Pacific
Family: Congridae
The Garden Eel, also known as Hass's Garden Eel, looks like a colony of seagrass.
The main portion of the Garden eel is usually buried in the sand, and if approached, retreats into the substrate. Several of these eels may be kept together in a 100 gallon or larger aquarium with at least 6 inches of sand, a gentle current, and without aggressive tank mates. Decor should be kept at a minimum. A tight-fitting lid is required to prevent escape.
The Garden Eel diet consists of meaty foods and live foods such as freshwater ghost shrimp or small feeder fish.
Approximate Purchase Size: 6" to 12"
so i would say not a chance in a nano tank.....