Edit Sicyopus exallisquamulus

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Name

Scientific name

Sicyopus exallisquamulus

Described by

Authority Watson & Kottelat, Year 2006

Family

Gobiidae

Summary

Sicyopus exallisquamulus is a stream goby described from the island of Halmahera in the Maluku Islands, Indonesia. It is normally misidenti…

Size and aquarium

Maximum size

52mm, standard length

Tank size

Minimum length 60 cm, Minimum depth 30 cm, Water movement High: fast-flowing river or riffle

Water

Temperature and pH

Temperature 22–28°C, pH 6.5–7.5

Hardness

2–12dGH

Conductivity

Not recorded

Behaviour

Temperament

Not recorded

Community suitability

Not for a community

Where it lives

Countries

Indonesia

Supporting text

Etymology

Not written yet

Distribution

Described from the island of Halmahera in the Maluku Islands (also referred to as the Moluccan or Spice Islands) archipelago, Indonesia. It may have a wider ra…

Habitat

Members of this genus are near-exclusive inhabitants of short coastal streams on tropical, often volcanic, islands, with typical habitats lying above waterfall…

Aquarium size

An aquarium with base dimensions of 60 ∗ 30 cm24 ∗ 12 in or equivalent is large enough for a pair or small group but use something bigger if you want to keep m…

Maintenance

These gobies aren't too difficult to keep provided some basic requirements are met. Most importantly the water must be clean and well-oxygenated at all times s…

Water conditions

Temperature: 22 – 28 °C72 – 82 °F; increased surface agitation is required to maintain dissolved oxygen levels towards the upper end of this range. pH: 6.5 – 7…

Diet

Appears to be a specialised predator since it does not graze biofilm in the aquarium but willingly accepts small live or frozen foods such as bloodworm, Artemi…

Behaviour and compatibility

Can be kept in a community provided tankmates are chosen with care. Peaceful, pelagic species which naturally inhabit well-oxygenated streams such as Tanichthy…

Sexual dimorphism

Adult males possess relatively long unpaired fins and the first dorsal-fin is noticeably extended compared with the second, whereas in females the unpaired fin…

Reproduction

Observations of courtship behaviour and the occasional spawning exist but to date no-one has managed to raise fry of any Sicyopus species in aquaria. This is u…

Notes

Live colouration of this species was not included in the original description but the specimens in our images were identified by Dr. Ronald E. Watson, the prin…

Live colouration of this species was not included in the original description but the specimens in our images were identified by Dr. Ronald E. Watson, the principal author, as S. exallisquamulus. It's normally misidentified and traded as the Sri Lankan endemic species Sicyopus jonklaasi.

It's diagnosable from congeners by the following combination of characters: 14-15 pectoral-fin rays; both genders exhibit small, widely-spaced scales below the first dorsal-fin, these being shaped ctenoid in males and cycloid in females; both sexes possess lobed urogenital papillae; dorsal-fin rays 3 and/or 4 are filamentous in males.

Watson (1999) defined three subgenera within Sicyopus based mostly on dental morphology. Juxtastiphodon has closely-set, conical teeth in both jaws of which none are recurved, and lacks canines. Sicyopus has widely-spaced conical teeth in both jaws of which most are sharply recurved, and lacks canines. Smilosicyopus has slightly recurved conical teeth in the anterior portions of both jaws which are needle-like teeth laterally and not recurved, with 1-3 canines between the anterior and lateral teeth.

Keith et al. (2011) elevated Smilosicyopus to genus level based on the results of their phylogenetic analyses within which Sicyopus zosterophorus and species of the subgenus Smilosicyopus did not group together, thus rendering Sicyopus polyphyletic. The three Smilosicyopus spp. were found to form a single, well-defined clade with the genus Stiphodon as sister group while S. zosterophorus was recovered in a different clade and appeared more closely-related with members of Akihito and Lentipes.

A nomenclatural change was thus required and since S. zosterophorus is the type species of Sicyopus it retained the name with Smilosicyopus used for the other clade as previously suggested by Watson. No Juxtastiphodon species were included in the study.

The Gobiidae is the most speciose vertebrate family and notoriously problematic in terms of identifying members down to species level. Sicyopus is often included in the putative subfamily Sicydiinae which currently contains at least six other genera; Cotylopus, Lentipes, Parasicyidium, Sicydium, Sicyopterus, and Stiphodon. Sicyopus and Lentipes species are omnivorous or carnivorous whereas the others are mostly herbivorous.

All share a similar life-history with many endemic to a particular island or group of islands, though a few are widespread. They also share some morphological characters including pelvic fins modified into a sucking disc with a strong spine and thickened, highly-branched rays, at the posterior edge of which the pelvic-fin spines and first ray are joined by a membrane forming 'fleshy pads' at the tips of the spines. The tongue is also fused to the base of the mouth, a feature shared by some other gobiids.

The fused pelvic fins form a structure normally referred to as the 'pelvic disc', a common feature among gobiids which is used to adhere to rocks and other submerged surfaces. In Sicyopus, as in Stiphodon, this is short-based and attached to the belly only between the fifth pair of fin rays whereas in other sicydiines it's attached between all five rays (Watson, 2005).

The role of the disc in ascending waterfalls and cascades has given rise to the common names of 'rock-climbing' or 'cling' gobies for members of the Sicydiinae in general. They're also sometimes referred to as 'toothed-lip' gobies in reference to the outwardly-orientated, replaceable teeth of the upper jaw.

Many of those being imported for the aquarium trade have proven difficult to identify for a number of reasons including:

- taxonomic confusion.
- lack of aquarium literature.
- incorrect labelling by exporters and subsequently shops.
- historical over-use of some names.
- likely trade of undescribed species without locality data.
- mixing of species at export facilities.

Thanks to Dr. Ronald E. Watson.

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References

6 on this profile

Name

Scientific name

Described by

Family

Summary

Size and aquarium

Maximum size

Tank size

Water

Temperature and pH

Hardness

Conductivity

Behaviour

Temperament

Social needs

Community suitability

Where it lives

Countries

Supporting text

Etymology

Distribution

Habitat

Aquarium size

Maintenance

Water conditions

Diet

Behaviour and compatibility

Sexual dimorphism

Reproduction

Notes

References

References