This is Elton, our new Helfrichi Firefish Goby. Very similar to the commonly seen Firefish Goby (or dartfish; see pic at bottom of post), unlike the Firefish Goby, the Helfrichi's are collected in deep water. However, as long as they are brought to the surface carefully so there is no damage to their organs, these guys are very hardy and adapt quite well to the bright reef aquarium set-up.
Taken with the beauty of this firefish and suitability to our aquarium, we coughed up the steep price and purchased one. They are expensive since they're fairly rare and highly sought after since they're so gorgeous. We named him "Elton" since he was so flamboyant. Elton is active, friendly, and peaceful, swimming about day and night. These guys are carnivorous. I feed him lots of mysis shrimp. He also loves the copepods from the refugium.
What else can I say? He's perfect. Small, shy, peaceful, he likes to hide in caves in the live rock (yet, he's out and about a lot too). He's reef-safe and also hardy. Plus, he'll stay small (about 3"). You have to keep a cover on; these guys are jumpers. Other than that, he's a perfect fit for our aquarium.
Below, the similar, more common Firefish Goby .