Chaetostoma formosae BALLEN, 2011

Striped Bulldog Pleco, L444, L187b

Classification

Order: Siluriformes Family: Loricariidae

Distribution

Known only from western piedmont streams within the upper río Meta and río Guaviare drainage systems, Meta and Casanare departments, eastern Colombia. Both the Meta and Guaviare are major tributaries of the río Orinoco.

Type locality is given as ‘Caño Chuy, affluent of río Upía, Boyacá – Casanare border, upper río Meta basin, Orinoco drainage, San Luis de Gaceno, Departamento de Boyacá, Colombia’.

Almost all collections for the aquarium hobby occur in the vicinity of the city of Villavicencio in Meta department, from where the fish are also exported. It occurs sympatrically with the congener C. dorsale and shipments often contain a mixture of both species.

Habitat

An obligate inhabitant of fast-flowing, sometimes high gradient, headwater streams and minor tributaries. Substrates are normally of bedrock with scattered jumbles of rocks and boulders, and while riparian vegetation and submerged leaf litter are common true aquatic plants aren’t usually present.

The most favourable habitats contain clear, well-oxygenated water which facilitates the development of a rich biofilm carpeting submerged surfaces, although turbidity, volume, and chemistry can change rapidly and often due to sometimes daily rainfall.

Maximum Standard Length

90 – 105 mm. The largest male specimen examined by Ballen (2011) 103.1 mm and the largest female 71.4 mm.

Aquarium SizeTop ↑

Base dimensions of 120 ∗ 30 cm or equivalent are required for long-term care.

Maintenance

Most importantly the water must be clean and well-oxygenated at all times so we suggest the use of an over-sized filter, additional powerheads, flow pumps, or airstones. While torrential conditions are unnecessary a turnover of 10-15 times tank volume per hour is recommended, though with good oxygenation a lower rate of 5-10 times per hour is feasible.

Base substrate can either be of gravel, sand, or a mixture of both to which should be added a layer of water-worn rocks and pebbles of varying sizes. Aged driftwood can also be used but avoid new pieces since these usually leach tannins which discolour the water and reduce the effectiveness of artificial lighting.

The latter should ideally be strong to promote the growth of algae and associated micro-organisms because Chaetodon spp. Some aquarists even maintain an open filter sponge in the tank to provide an additional food source.

Although not a feature of this species‘ natural habitat aquatic plants can be used with hardier genera such as Microsorum, Crinum, and Anubias likely to fare best. The latter are particularly useful as their leaves tend to attract algal growth and provide hiding places.

Since it needs stable water conditions it should never be added to immature set-ups, and weekly water changes of 30-50% tank volume should be considered essential. The rest of the tank needn’t be kept too clean, though,  and algae can be allowed to grow on all surfaces except the viewing pane.

Water Conditions

Temperature: 20 – 24 °C

pH: 6.5 – 7.8

Hardness: 143 – 447 ppm

Diet

Primarily an aufwuchs grazer feeding on algae, small crustaceans, insect larvae, etc., and for it to develop its best colours and condition it should be offered regular meals of small live and frozen foods such as bloodworm, Daphnia and Artemia, alongside plenty of fresh algae. Home-made, gelatine-bound recipes may also work provided the ingredients are chosen with the target species in mind.

Some specimens will also learn to accept good quality sinking dried foods or fresh fruit and vegetables such as shelled peas, cucumber, blanched courgette, spinach, and chopped fruit, but none of these are accepted as readily as algae which should be available on a constant basis.

If unable to grow sufficient algae in the main tank or you have a community containing numerous herbivorous fishes which consume what’s available quickly, it may be necessary to maintain a separate tank in which to grow algae on rocks and switch them with those in the main tank on a cyclical basis. Such a ‘nursery‘ doesn’t have to be very large, requires only strong lighting and in sunny climates can be maintained outdoors.

Unfortunately as a result of their specialised diet and oxygen requirements Chaetostoma spp. are regularly seen on sale in an emaciated state which can be tricky to correct. A good dealer will have done something about this prior to sale but if you decide to take a chance with severely weakened specimens they’ll initially require a readily-available source of suitable foods in the absence of competitors if they’re to recover.

Behaviour and CompatibilityTop ↑

This species does best in a dedicated species set-up, either alone or with a school or two of peaceful, open water-dwelling charaids or cyprinids able to cope with the necessary water movement.

It can be territiorial towards congeners and similarly-shaped fishes so if the aim is to maintain it in a group or community containing other loricariids be sure to structure the décor in such a way to provide many broken lines of sight and refuges.

Sexual Dimorphism

Sexually mature males possess an enlarged second unbranched anal-fin ray that develops two posterior, longitudinal, fleshy ridges which can reach the caudal-fin base in fully-grown individuals. Males also develop a fleshy ridge along the dorsal surface of the first pectoral-fin ray, with all these characters absent in females.

Males also grow noticeably larger, have a relatively larger unplated area on the snout, and exhibit more pronounced odontote development on the pectoral-fin spines than females, with the dorsal series of the latter recurved in males vs. straight in females.

The distal margin of the pelvic-fin is convex in both sexes but is angular in males and rounded in females. Males develop several rows of acute, recurved, hypertrophied odontotes which protrude from the skin on the dorsal surface of the pelvic-fin rays whereas in females the odontotes are visible but do not pierce the skin.

The genital papilla is pointed and discrete in males, wide and pad-like in females, and though it has a terminal aperture in both, the posterior portion becomes swollen in sexually-mature, gravid females which makes the papilla appear to be adjacent to the vent.

Reproduction

Reports of captive spawning are few and far between, tending to occur in well-established set-ups rather than dedicated breeding aquaria. Eggs are apparently deposited on the roof of a cave and defended by the male.

NotesTop ↑

This is the commonest member of the genus in the aquarium hobby though it continues to be misidentified as C. thompsoni or C. cf. thompsoni. It’s also traded under a number of English vernacular names including ‘blonde bulldog pleco’, ‘blonde rubber pleco’, ‘blonde rubbernose pleco’, ‘striped rubber pleco’, ‘striped rubbernose pleco’, and ‘widemouth pleco’. It may also be seen referred to as ‘L146’, ‘L146a’, or ‘L187b’, these codes having been used for it in the Aqualog series of books.

It can be told apart from all congeners except C. anale and C. jegui by the enlarged second unbranched anal-fin ray with two distinct fleshy ridges reaching the caudal-fin base when fully-developed. It differs from C. anale by the angular distal pelvic-fin margin in mature males (vs. W-shaped in mature C. anale males) and lacking an extended leading pelvic-fin ray (vs. leading pelvic-fin ray enlarged, filamentous, and longer than other rays).

C. formosae differs from C. jegui by possessing dark spots only on the head and dorsal region around the dorsal-fin base and with compound pterotic and lateral plates bordered by dark pigment (vs. dark background with light blotches in C. jegui), and by the strongly-prohected, angular distal pelvic-fin margin in mature males (vs. distal pelvic-fin margin straight and with leading ray sometimes extending beyond distal margin of fin).

These three species are recognised collectively as the C. anale species group within the genus Chaetostoma by Ballen (2011).

The family Loricariidae is the largest among catfishes with over 700 species described to date and many awaiting description. The latter are typically assigned a specific ‘L’ number by hobbyists and scientists alike in order to provide a basic means of identification, although in some cases several species have been referred to the same number, or multiple numbers have been used for different populations of a single taxon. All loricariids are also commonly referred to as ‘pleco’, ‘plecostomus’, or ‘suckermouth armoured catfishes’.

The closer relationships of member genera have long been of interest to icthyologists but in numerous cases remain unresolved. Isbrücker (1980) was the first to propose an arrangement of six subfamilies, namely Lithogeneinae, Neoplecostominae, Hypostominae, Ancistrinae, Hypoptopomatinae, and Loricariinae, and this model was generally followed until publication of Armbruster’s morphological analysis in 2004.

His phylogeny also contained six subfamiles, with Isbrücker’s (1980) Ancistrinae being included as one of five tribes comprising Hypostominae. This was later modified slightly by Reis et al. (2006) and an adapted version of their key is reproduced here:

1a. No lateral and dorsal plates anterior to the dorsal fin: Lithogeneinae
1b. Possession of lateral plates anterior to the dorsal fin (except in Pareioraphis nudulus): 2
2a. Ventral surface of the pectoral girdle exposed (i.e. supporting odontodes) towards the centre of the coracoid strut: Hypoptopomatinae
2b. Ventral surface of the pectoral girdle covered in skin or plates towards the centre of the coracoid strut (odontodes supported by the plates rather than the girdle): 3
3a. Caudal peduncle flattened dorsoventrally; no adipose fin: Loricariinae
3b. Caudal peduncle oval, round, or triangular in cross-section; adipose fin usually present: 4
4a. Postdorsal ridge formed from several preadipose plates arranged singly. Teeth almost symmetrically bifid (divided into two equal parts): Delturinae
4b. Usually no postdorsal ridge. Teeth asymmetrical or unicuspid: 5
5a. Dorsal–fin spinelet V-shaped, dorsal–fin spine can be locked: Hypostominae
5b. Dorsal–fin spinelet rectangular or absent, dorsal–fin spine cannot be locked: Neoplecostominae

Subsequent papers attempting to resolve relationships within the Hypoptopomatinae and Neoplecostominae by Cramer et al. (2008, 2011) have revealed both subfamiles to be polyphyletic arrangements alongside several genera, e.g., Pareiorhaphis, Pareiorhina, Hisonotus, and Parotocinclus, so there is evidently a great deal of work still to be done. At any rate Chaetostoma is currently considered a member of the tribe Ancistrini within Hypostominae.

The sucking disc formed by the mouthparts is common to all representatives but both oral and dental morphology are highly variable depending on a given species‘ ecological adaptation(s), with some even practising xylophagy (wood-eating). Many are also facultative air-breathers, i.e., they possess the ability to respire atmospheric air if necessary.

References

1. Ballen, G. A., 2011 - Papéis Avulsos de Zoologia, São Paulo 51(6): 383-398
   A new species of Chaetostoma Tschudi (Siluriformes: Loricariidae) from Colombia with a definition of the C. anale species group.
2. Armbruster, J. W., 2004 - Zoological Journal of the Linnean Society 141: 1-80
   Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae.
3. Cramer, C. A., A. M. R. Liedke, S. L. Bonatto, and R. E. Reis, 2008 - Bulletin of Fish Biology 9: 51-59
   The phylogenetic relationships of the Hypoptopomatinae and Neoplecostominae (Siluriformes: 725 Loricariidae) as inferred from mitochondrial cytochrome c oxidase I sequences.
4. Cramer, C. A., S. L. Bonatto, and R. E. Reis, 2011 - Molecular Phylogenetics and Evolution 59(1): 43-52
   Molecular phylogeny of the Neoplecostominae and Hypoptopomatinae (Siluriformes: Loricariidae) using multiple genes.
5. Reis, R. E., E. H. L. Pereira, and J. W. Armbruster, 2006 - Zoological Journal of the Linnean Society 147(2): 277-299
   Delturinae, a new loricariid catfish subfamily (Teleostei, Siluriformes), with revisions of Delturus and Hemipsilichthys.