Ctenopoma weeksii

Mottled Bushfish

Classification

Anabantidae

Distribution

Known from parts of the River Congo drainage in both the Republic of Congo and Democratic Republic of Congo.

Habitat

It’s mainly found in sluggish or still, often hypoxic (oxygen-deprived) waters, including various pools, lakes, lagoons and swamps. Within these it’s usually collected in marginal areas where the vegetation is thickest, presumably as this provides added protection from predators.

Maximum Standard Length

Around 4″ (10cm).

Aquarium SizeTop ↑

A 30″ x 12″ x 12″ (75cm x 30cm x 30cm) – 71 litre tank is ok for a single fish. Roomier quarters would be preferable if you fancy a group.

Maintenance

It’s naturally most active during the hours of twilight, and prefers dim conditions in the aquarium. Either use weak lighting, or diffuse it by adding a layer of floating plants. Arrange the rest of the decor to form plenty of hiding places and cover. A dark substrate with African plant species such as Anubias and Bolbitis attached to pieces of driftwood looks particularly effective. Make sure there are no gaps around the tank cover as Ctenopoma do jump on occasion.

Water Conditions

Temperature: 75 – 82°F (24 – 28°C)

pH: 6.2 – 7.2

Hardness: 5 – 15°H

Diet

Although it’s a predator by nature, it’s very easy to wean onto dead alternatives. Offer a varied diet comprising frozen foods such as prawn, bloodworm, mussel etc., along with the occasional live treat of earthworms or mealworms. Dried foods are not usually accepted, although some specimens do learn to take them.

Behaviour and CompatibilityTop ↑

Not aggressive as such but is a predator by nature and will eat small fish. Ideal tankmates include other species from the same region. Shoals of congo tetras, Phenacogrammus interruptus, yellowtail congo tetras Alestopetersius caudalis and Barbus species, along with catfish such as Synodontis flavitaeniatus or schoutedini are all suitable. You could also try it with other oddballs, such as the smaller species of Polypterus or the African butterfly fish, Pantodon buchholzi. Don’t keep it with anything too large or aggressive though, as it has a rather retiring character and might start to hide away if it feels threatened.

It can be maintained in a group in a big enough tank, provided all the fish are added simultaneously. If they’re introduced at different times there can be some real conflict over territories.

Sexual Dimorphism

Not easy to sex. Males have more spines on the gill covers, and a roughly textured area at the base of the caudal peduncle that is absent in females.

Reproduction

It’s thought that C. weeksi and other egg-scattering members of the genus are seasonal spawners in nature, as a pair will often spawn regularly for several months and then stop for a while. This does not appear to be related to water chemistry or temperature. There is also a general school of thought that these fish may not become sexually mature until they are several years old.

Possibly as as a result of this there are very few reports of this fish spawning in the hobby. If you fancy a go the chances of obtaining a compatible pair should be increased by obtaining a group of young fish and allowing them to pair off naturally. The breeding tank should be large and contain lots of floating plants. Apparently the pair embrace in the usual anabantoid fashion at which point eggs and sperm are released together. The eggs then float to the surface where they come to rest among the floating vegetation. The adults exhibit no parental care and should be removed at this point. The eggs hatch after 48 hours and the fry become free swimming quite quickly. Infusoria should be offered for the first couple of days after which the fry will accept Artemia nauplii.

NotesTop ↑

There are currently 20 species of Ctenopoma, most of which most are seldom seen in the aquatic trade. Originally the genus was significantly larger, but a number of original members were reclassified by Norris in 1995. Whilst describing what were apparently two new Ctenopoma, he discovered sufficient morphological anomalies in the fish to erect a new genus for them. The name Microctenopoma was chosen, although this does not relate to the size of the fish. Similar defining characteristics were also found in a handful of existing Ctenopoma species and these were also placed in the new genus, which now numbers a dozen.

Ctenopoma appear to exhibit convergent evolution with the South American Leaf fish of the Polycentrus and Monocirrhus. Members of these groups have evolved to mimic leaves and other aquatic debris to assist them in stalking their prey. If you want to see this characteristic behaviour in your fish, simply add some live food to the tank.

All Ctenopoma can be considered good choices for the newcomer to “oddballs”, being exceptionally hardy, long-lived (they can survive for over 15 years when cared for properly) and in possession of some interesting behaviour. Like others in the suborder Anabantoidei, these fish possess an accessory breathing organ known as the labyrinth organ. So-called due to its maze-like structure, this organ allows the fish to breathe atmospheric air to a certain extent. It is formed by a modification of the first gill arch, and consists of many highly vascularised, folded flaps of skin. The structure of the organ varies in complexity between species, tending to be better developed in those inhabiting particularly oxygen-deprived conditions.

C. weeksii may also be seen for sale with the invalid name C. oxyrhynchum. The common name of mottled bushfish refers to its ability to change colour very quickly when startled, when it takes on a mottled appearance. Usually the fish appears brown with a large spot on either side