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Theraps coeruleus - An Odd Cichlid From Mexico

The January 2004 edition of Today's Fishkeeper contained an article (pages 22-24) on an unusual Cichlid from Mexico, called Theraps coeruleus.This is an interesting, intriguing and fairly challenging species for the experienced Cichlid enthusiast, and one that is likely to be rare in the hobby for some time to come. The credit for much of the information presented here is due to the author of the original article, Juan Miquel Artigas Azas, who is a specialist in Mexican Cichlids.

The species was first collected by Rainer Stawikowski, editor of the renowned DATZ magazine, who visited Mexico in 1983 with other German aquarists and ichthyologists on an expedition to the Usumacinta Drainage, a habitat with an unusual and interesting fish fauna worth studying by other fishkeepers as well as Cichlid fans. Stawikowski recognised that some of the Cichlids he had collected potentially belonged to a new species, which was finally described in DATZ as 'A new subspecies of Thorichthys helleri' in 1987, then later reclassified as Theraps coeruleus. The type locality for the species is a tributary of the Rio Mizol-Ha, near a location called Francisco I. Madero - this is approximately 30 Km south of Palenque, Chiapas State. Theraps coreuleus appears for the time being to be restricted to the middle zone of the Tulija River and its affluents in the Grijalva-Usumacinta River system.

Habitat details for the species are described in the article thus: wide rivers (over 5 metres wide typically), flowing through montane regions, temperature range 20C to 27C, water clear (transparency 10 metres), chemistry hard and alkaline (pH measurement range 7.5 to 8.4, 11-22 GH, 7-28 KH). River beds composed of mixed regions of boulders, smaller rocks, gravel and sand, with backwater areas of sunken leaf layer present in the slower flowing sections. Theraps coeruleus chooses by preference moderately fast flowing sections of water, away from the strongest currents, but likewise away from stagnant regions, visiting regions of slower current when breeding.

This Cichlid is remarkable for the numerous colour changes that take place during the breeding cycle. Normal non-breeding colouration is sexually dichroic: females possess a brownish base colour, with a strong blue suffusion in the ventral region of the body, reaching back to the anal fin from the mouth, while males are normally greenish-yellow with 6-7 black blotches roughly following the midline of the fish. Females take the initiative in breeding, by seeking caves in which to raise their young. The most desirable such sites are usually holes in sunken tree trunks, separated from the bottom, and the largest and most aggressive females colonise these rapidly. Caves formed naturally by rocks are next on the desirability list, with those females at the bottom of the pecking order sometimes reduced to excavating a cave beneath a rock lying upon the substrate.

Females in breeding condition and preparing to breed, once having selected a suitable territory, undergo a significant colour change. The usual faint black blotches on the body are replaced by light blotches, described as 'white' in the article, but in the accompanying photograph seemingly closer to creamy beige. The blue in the dorsal, pelvic and anal fins intensifies.

Males begin patrolling outside female territories, largely ignored until a female selects a potential mate. She then courts him, and once a pair bond is established, the pair begin chasing away all rivals from the breeding cave. At this point, a second colour change takes place: the reason for the scientific name coeruleus becomes apparent, as both sexes develop a sky blue body colour with just a black blotch on the middle of the flanks. Males and females at this stage possess a similar intensity of colouration, and are generally distinguished by the larger size of the male, and the difference in behaviour: females remain closer to the breeding cave, while males patrol more extensively on 'guard duty'. This division of labour extends throughout the breeding cycle.

Both parents will clean the spawning site, usually the roof of the cave, and up to 200 eggs (described as yellow, ovoid, 2.1mm long by 1.7 mm wide) will be deposited. The female performs the egg-fanning duty, while the male resumes outdoor guard duty. Egg hatching time is cited as 48 hours, and 4 days later, the fry become free-swimming.

Once the fry are free-swimming, yet another colour change takes place in the adults. A dark pattern overlays the sky blue (in some individuals, almost lavender) base colour, in the form of 6 incomplete bars descending from the base of the dorsal fin, meeting with rows of midline black blotches (the light blotches of the females have now turned black at this point). An unusual additional marking, in the form of a black 'U', appears at the anterior base of the dorsal fin as seen from above.

Fry are herded in moderately fast water, and the fry forage on rock surfaces for encrusted larvae, detritus and aufwuchs. When danger threatens, the fry disappear into the rock crevices, leaving the parents apparently guarding nothing, until by some as yet undetected signal, the fry become aware that danger has passed, and pop out of their hiding places one by one.

In the wild, juvenile fish up to 2 cm long were witnessed wandering along the rocks in the manner of smaller fry, and joined the adults foraging at 4 cm. Observations of aquarium breeding remain to be documented, though given the above, several clues as to how to succeed with this species, whose colour changes are themselves worthy of further scientific investigation, are presented in the article.

Requirements for successful maintenance cited include the presence of dither fish, and correct lighting. Theraps coeruleus is a shy species, and if conditions are not correct, this shyness becomes extreme, resulting in stress and a seriously shortened lifespan. The fish requires good but not excessively bright lighting (dark conditions will worsen its shyness), and a good provision of caves in its aquarium, which must be spacious. The author recommends 300 litres as a minimum volume. Non-breeding fishes in the wild actually shoal when foraging, although in the aquarium, this behaviour is more likely to be replaced by the usual Cichlid territoriality. The species is described as possessing a moderately aggressive disposition, although outbreaks of open warfare are likely to be few.

The clear, well-oxygenated waters of the home of Theraps coeruleus MUST be replicated if the fish is to survive for any length of time. In poor water conditions, this species is very e to bacterial infections, hastening its demise. The aquarium MUST be well filtered, with good currents replicating those of its wild habitat, and the fish is e to stress brought on by insufficient dissolved oxygen. High temperatures will also induce potentially fatal stress. Aquarists should aim for around 23C as an optimum temperature, with little deviation, and aim to reproduce the hard, alkaline conditions of their native waters as given above.

Theraps coeruleus seems to need a good assemblage of dither fish for its well-being. Too aggressive companions will prevent them forming territories, and insufficiently active dither fish will do nothing to reduce the species' natural shyness. Dither fish are largely ignored, although small ones may be eaten: among the other fish species found in its natural habitat are Swordtails, Xiphophorus helleri, the livebearer Pseudoxiphophorus bimaculatus, the Mexican Characin Astyanax mexicanus and an Atherinid called Atherinella alvarezi. Any fish of a similar size and disposition to the Swordtail is likely to prove a good dither fish. Incidentally, the fish also shares its native waters with much more aggressive Cichlids, namely Salvinis and Dempseys, but mixing these in the aquarium is probably NOT recommended!

The aquarist is recommended by the author to keep six or more Theraps coeruleus in a spacious aquarium with copious cave provision, accompanied by a good number of dither fish. They will breed under such conditions, if water chemistry is correct and oxygenation levels are high, and the fry will not only survive alongside the dither fish (provided that these are not efficient fry predators of course!) but prosper. If fry are produced, and parents may require several spawning attempts to be successful at producing fry, then these can eat newly hatched Brine Shrimp from the very first, graduating quickly to larger foods. Feeding Theraps coeruleus presents no major problems if the species is properly acclimatised and in good quality water: in fact, it can be a greedy feeder. Avoid protein rich or fatty foods (as per those other well-known Cichlid inhabitants of hard, alkaline water, the Mbuna - strange that a riverine Mexican Cichlid should have similar requirements!), but otherwise, most foods are not so much accepted, as devoured.

This rarity among Cichlids is intriguing because of the numerous colour changes cited above, that are a feature of its breeding cycle, and which may be a sophisticated signalling mechanism in its own right. Other aspects of the fish's behaviour, including the pre-eminence of the female in breeding, and the idiosyncratic approach to parenting accompanied by a division of labour, make this fish a good subject for a long-term research study project.

If any of the Cichlid devotees on this board find this unusual species, and want to try their hand to persuading it to breed in order to see its coat of many colours, the above details should be a good starting point. And if any of you DO find this rarity and breed it, don't forget to post pictures in the Photo Booth, not least because outside Germany, chances are you'll be among the first to succeed with this unusual Cichlid, and your observations will not only be welcome to other aquarists, but of real scientific value too!

Enjoy!



[span class="edited"][Edited by Calilasseia 2004-07-14 09:29][/span]

Panda Catfish fan and keeper/breeder since Christmas 2002

very interesting, I will look for those around here in the states.

good luck finding them...about your only chance would be an importer and/or breeder.

Note, I am led to believe the Theraps genus in general consists of abnormally shy fish. I have Theraps wesseli and was told they are quite active as juveniles, but will become much more shy and reclusive as they mature.

Jason

yea that might be rather hard to find, but If I ever see one, I'll snatch it up.

Jason, post pics of your wesseli at the earliest opportunity & link to them here ... I want to see this one!

Oh, and there's quite a few pics of coeruleus doing the rounds on the web. Some of them are quite nice too.

Oh, and if you do a Google search on "Juan Miquel Artigas Azas", chances are he may have his own website, with him being a Mexican cichlid taxonomist ...

Panda Catfish fan and keeper/breeder since Christmas 2002

I will try to get pics of mine, but until then you can see a couple pics here. select "Central American Cichlids", scroll down and you'll find Theraps wesseli. There are 2 pics both taken by the founder of the species Rusty Wessel. The coloration of the fish in the first pic looks to be washed out a bit from the flash. They actually have a very nice yellow coloration. The only other thing I noticed is that the red coloration at the tip of the dorsal fin looks washed out as well. The second pic is a female in breeding coloration. I know females exhibit that breeding coloration but I can't remember for sure if males do or not.

The species has been described as a New World Auratus. In breeding colors they look very similar to H. bartoni.

Jason

Nice fish Jason. I guess you'll be looking out for some coeruleus to go with them

Panda Catfish fan and keeper/breeder since Christmas 2002

chances are the only way I'd be able to get T. coeruelus is through Rusty Wessel as I got the T. wesseli from him.

Jason

You know the guy that your wesseli are named after? Serious kudos! Even more when I read that you got your fish from him ... I'm in elevated company!

If ever you get to meet Juan Miquel Artigas Azas, get him to supply you some Paraneetroplus bulleri ... they're as rare as the proverbial rocking horse doo-doo in the hobby ...

I take it you're working hard on a wesseli breeding project then?

Panda Catfish fan and keeper/breeder since Christmas 2002