TankBud

Threadfin sicyopterus

Sicyopterus longifilis

Also known as Funky goby, Longifilis goby

FreshwaterFish

Threadfin sicyopterus (Sicyopterus longifilis)

Care at a glance

Temperature
73–81°F
23–27°C
pH
6.5–7.8
Adult size
3.9 in
10 cm
Minimum tank
29 gal
110 L
Temperament
Peaceful
Social behavior
Social
Swim level
Bottom
Difficulty
Difficult
Breeding
No record
Rarity
Rare
Family
Oxudercidae
Origin
Indonesian and New Guinea streams

Overview

The threadfin sicyopterus is a river-current grazer for a mature, fast-flowing tank. It is for experienced keepers.

Did you know

The male threadfin sicyopterus uses his trailing thread as display gear. In a strong current, a courting male streams that extended fin ray out behind him like a pennant. He flies it over the patch of rock he grazes and guards.

Caring for the threadfin sicyopterus

Set up the hardware before the threadfin sicyopterus arrives. Give it a mature tank of at least 29 gal (110 L), with strong flow, high oxygen and open swimming lanes. Leave smooth stones and cobbles under bright light to grow the film of algae and biofilm it grazes.

Hold the water at 73 to 81°F (23 to 27°C), with a pH of 6.5 to 7.8. Plants are optional, but oxygen and current are not.

The threadfin sicyopterus works the bottom, rasping the film off stone with a sucker-like mouth. A bare or spotless tank will slowly starve it. Supplement the grazing with algae wafers, blanched vegetables and some frozen foods.

It is peaceful and can live in a small group of its own kind, alongside other calm, flow-tolerant fish. Mature males draw the second dorsal fin out into a long trailing thread. Like other Sicyopterus, it is amphidromous, with a marine larval stage, and no aquarium breeding has been documented.

Good to know

Sicyopterus longifilis is a goby of the family Oxudercidae, subfamily Sicydiinae. Its species name refers to a long filament. Young fish returning from the sea gather in such numbers that in parts of its range they are netted and eaten. It is also known as the funky goby or longifilis goby.

In the wild

In the wild, the threadfin sicyopterus holds station in fast, clear hill streams across eastern Indonesia and New Guinea. It clings to rock in the current, where sunlight grows a carpet of diatoms and algae.

Weekly picks

Tank mates

The threadfin sicyopterus is a peaceful, social species that keeps to the bottom. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a threadfin sicyopterus need?

A threadfin sicyopterus needs at least 29 gal (110 L). It spends most of its time in the bottom.

What temperature and pH does a threadfin sicyopterus need?

A threadfin sicyopterus is comfortable at 73–81°F (23–27°C) with a pH of 6.5–7.8.

What does a threadfin sicyopterus eat?

A threadfin sicyopterus rasps the film of algae and biofilm off stone with its sucker-like mouth. Supplement its grazing with algae wafers, blanched vegetables and some frozen foods.

How big does a threadfin sicyopterus get?

An adult threadfin sicyopterus reaches about 3.9 in (10 cm).

How can you tell a male threadfin sicyopterus from a female?

Mature males draw the second dorsal fin out into a long trailing thread.

How does a threadfin sicyopterus breed?

The threadfin sicyopterus is amphidromous, with a marine larval stage. No aquarium breeding has been documented.

Related species