Rainbow sicyopus

Sicyopus auxilimentus

Also known as Auxilimentus goby, Rainbow goby

FreshwaterFish

Care at a glance

Temperature: 73–81°F (23–27°C)
pH: 6.5–7.8
Adult size: 1.4 in (3.5 cm)
Minimum tank: 14 gal (54 L)
Temperament: Peaceful
Social behavior: Social
Swim level: Bottom
Difficulty: Difficult
Breeding: No record
Rarity: Rare
Origin: Philippine and Sulawesi streams
Family: Oxudercidae

Overview

This looks like an algae goby but is a tiny carnivore, so feed it as a micro-predator rather than expecting it to graze. Gentle and sociable, it does well in a small group over cobbles and boulders in a fast tank, with males given room to hold a stone and display their colors. It stays low in the current and takes small meaty foods, so offer frozen and live items such as cyclops, baby brine, and finely chopped bloodworm, drifted into the flow. Keep only calm, small tankmates that will not out-compete it for these fine foods. A well-oxygenated 54 liter tank with steady current suits a small group.

In the wild

In the wild it lives in clear, fast island streams in the Philippines, holding to rock and cobble in warm, oxygen-rich water swept by current. Reproduce that with strong flow from a powerhead, rounded stones and boulders for perching and cover, and very clean water changed often. Run it at 23 to 27 C with a pH from slightly acidic to slightly alkaline, around 6.5 to 7.8, under a tight lid, since these gobies climb.

Good to know

Sicyopus auxilimentus is a member of the family Oxudercidae, described by Watson and Kottelat in 1994 from a single creek on Leyte in the Philippines. It is small, reaching about 3.5 centimeters. Sicyopus species are not grazers at all but small carnivores that pick off tiny invertebrates. Its larvae develop at sea, and it has no aquarium breeding record.

Did you know

Though it wears the colors of the algae-grazing gobies, it earns its living as a tiny hunter of small invertebrates. It was described from just one creek on Leyte, the same stream that produced several other rare gobies.