• Source: Cichla temensis

Cichla temensis, the speckled peacock bass, painted pavon, royal pavon, speckled pavon, three-barred peacock bass, or striped tucunare, is a very large South American cichlid. Reaching nearly 1 m (3.3 ft) in length, it is the largest cichlid of the Americas, and one of the largest extant cichlids in the world. It is an important predator in its native waterways, as well as a prized food fish and game fish, which has led to a number of attempted introductions outside of its native range.




Description


C. temensis resembles other peacock bass species, but is generally more elongate and slender in body shape. It is one of the largest cichlids in the world, reaching a maximum recorded length of 99 centimetres (39 in) and 12.2 kg (27 lb) in weight, with only the African giant cichlid (Boulengerochromis microlepis) possibly reaching similar proportions.
C. temensis is characterized by possessing a post-orbital band (the dark marking between the eye and the opening of the gills), as opposed to other Cichla species which have either irregular blotches or lack them entirely. It is closest in overall patterning to C. pinima and C. vazzoleri.

Adults are highly variable in colour pattern, which has historically caused confusion; some authors speculated that the variants were a separate species or sexual dimorphism. Only in 2012 was it firmly established that the differing color morphs were seasonal; dark individuals with dense, light-hued speckles - called the speckled peacock or tucunaré paca - are the non-breeding individuals, while breeding adults - the three-barred peacock or tucunaré açu - lose the pale speckles entirely but develop a golden-olive coloration which contrasts highly with the dark bars on their flanks, and a vibrantly colored ventral region. During the breeding season, some males also develop a bulbous forehead; or the nuchal hump, which is the only visible point of difference between the genders. The study also distinguished 2 other morphs, or grades, intermediate between the two mentioned prior. The 4 distinct grades were confirmed not to be the result of sexual dimorphism or regional variation through analysis of morphology and genetics. This variation in pattern is greater than what was observed between individuals of C. orinocensis and C. monoculus.




Distribution



C. temensis is native to the Orinoco and Rio Negro basins, as well as several smaller rivers in the central Amazon (Uatumã, Preto da Eva, Puraquequara, and Tefé), in Brazil, Colombia, Venezuela, and Guyana.
Introduction attempts have been made outside its native range, but it has not managed to become established in Florida or Texas due to extreme temperatures. In contrast, it has flourished in tropical Singapore and Malaysia.




Biology


The species is benthopelagic, found near the shoreline of lagoons and areas of the main river channel with sandy or rocky banks. In its native range, it is essentially restricted to blackwater rivers and their tributaries. They are comfortable in waterways with little cover, but non-breeding individuals may shelter near submerged wooden debris to avoid predation. The species had mostly been studied during the dry season; its habits during the rainy season are less known. C. temensis are largely sedentary, but occasionally, some individuals are known to have migrated across flood plains to other river tributaries during the rainy season.




= Feeding

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C. temensis is a diurnal predator, hunting fish that it can swallow whole; it has been described as a potential keystone predator. The coloration of the non-breeding tucunaré paca, a dark olive with extensive speckling all over, is theorized to provide an excellent camouflage in the tannin-stained waters and the dappled light in the flooded forests, allowing it to ambush prey in the tangled environs. Small prey items include the tetra Hemigrammus analis, Nannostomus pencil fish, anostomids, and pike cichlids. C. temensis is noted to hunt larger prey than other sympatric peacock bass, hunting down a variety of fish such as the characiformes Semaprochilodus kneri and Acestrorhynchus heterolepis, Pimelodella sp., armoured catfish, and cichlids including smaller peacock bass, although cannibalism might be more prevalent in fish stuck in isolated lagoons and reservoirs during the dry season, and the exact species of consumed peacock bass cannot be determined. Juvenile prochilods on migration are preyed on heavily by the opportunistic peacock bass, at times comprising nearly half of the biomass consumed by C. temensis. This glut of food allows the peacock bass to reach a healthy breeding condition.




= Spawning

=

Cichla temensis begin breeding at the end of the dry season, and part of the population likely continues breeding in the ensuing rising-water period and rainy season. Due to strong seasonal variation and extent of provided parental care, the species is typically restricted to breeding once a year in its natural flood-pulse river habitat. The tucunaré açu are visibly "blockier" in appearance than non-breeding adults, having a higher ratio of height:standard length; some of this is due to the formation of fat deposits on the body. C. temensis may begin breeding at a total length of ~300 millimetres (12 in); males tend to be bigger than their partners, ranging from ~20% to more than 300% the weight of the female.
Pairs prepare a site with adequate hardscape - such as a rock or live or dead standing tree - at a depth of 1–1.5 metres (3.3–4.9 ft) to adhere their eggs to. The male clears the area of detritus and may dig small pits to position the newly-hatched larvae. The female's fecundity ranges from under 2000 eggs to over 10000, which may be correlated to her body mass. While they do not mouthbrood their fry like some other cichlids, one or both parents vigilantly guard their brood - and the subsequent school of fry - from potential predators, fasting all throughout this period. The fry hatch after 48 hours, and become free swimming after 2-3 days of absorbing their yolk. The planktivorous fry are guarded for about 2 months or until they reach about 60 mm standard length, after which they disperse and begin their independent lives. Dispersed juvenile fish may form shoals with their fellows. Peacock bass are prone to interspecific hybridization; Cichla temensis itself has been found to naturally hybridize with Cichla monoculus in the Central Amazon.




= Natural threats

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The amazon river dolphin and the piranha Serrasalmus manueli have been noted to attack various species of peacock bass, including C. temensis, that were hooked or being released. Additionally, piscivorous snakes, black caiman, and giant river otter also preys on C. temensis. This peacock bass is parasitized by the crustaceans Amazolernaea sannerae and Argulus multicolor along with the trematodes Aspidocotylus cochleariformis and Clinostomum heluans.




Commercial value



C. temensis is fished both commercially and for sport; it is a popular gamefish akin to other peacock bass due to its energetic fight when hooked. Fishing for peacock bass is regulated in Florida, although C. temensis itself was not successfully established and was not restocked. The species, alongside other peacock bass, is fished intensively in its native range, but the effects of this fishery is not well studied despite its importance; some authorities deem it as the most important inland fishery of South America, but research into distinct stocks are ongoing.




References

Kata Kunci Pencarian:

• Cichla temensis
• Peacock bass
• List of freshwater game fish
• Cichla orinocensis
• Giant cichlid
• Adaptive radiation
• Bass fishing
• Cinaruco River
• List of fishes of Florida
• Index of Singapore-related articles