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Peacock Bass - Spectacular Cichlids for Big Aquaria
The fish we call Peacock Bass are in fact cichlids despite their superficial similarity to things like Sea Bass (Dicentrarchus labrax) and Largemouth Bass (Micropterus salmoides). Fifteen species are currently recognised, all of which are placed in the genus Cichla. They are all rather similar in size and shape, but differ in terms of colouration and, in some cases, behavioural habits.
Peacock Bass are among the biggest and heaviest cichlids, but given sufficient space and adequate filtration they can do rather well in captivity. In fact several species have been traded on a fairly regular basis, most frequently the Common Peacock Bass Cichla occelaris but other species turn up periodically as well. Use the Tropical Fish Finder search tool at the top left of the home page to find retailers currently stocking these magnificent fish, but be sure to plan ahead before making your purchase. As will become clear in the following article, these fish need big tanks and heavy-duty filters.
Fishbase currently lists 15 species of Peacock Bass, of which no fewer than 9 species were only recently described in a 2006 review by Sven Kullander and Efrem Ferreira.
Cichla intermedia Machado-Allison, 1971
Cichla jariina Kullander & Ferreira, 2006
Cichla kelberi Kullander & Ferreira, 2006
Cichla melaniae Kullander & Ferreira, 2006
Cichla mirianae Kullander & Ferreira, 2006
Cichla monoculus Spix & Agassiz, 1831
Cichla nigromaculata Jardine & Schomburgk, 1843
Cichla ocellaris Bloch & Schneider, 1801
Cichla orinocensis Humboldt, 1821
Cichla pinima Kullander & Ferreira, 2006
Cichla piquiti Kullander & Ferreira, 2006
Cichla pleiozona Kullander & Ferreira, 2006
Cichla temensis Humboldt, 1821
Cichla thyrorus Kullander & Ferreira, 2006
Cichla vazzoleri Kullander & Ferreira, 2006
At least two other species are recognised that have not yet been formally identified. As noted earlier, many of these species do look rather similar and telling them apart can be hard. However, the Fishbase pages on each species do list the key features used to tell that fish apart from similar-looking species, and this can be useful in situations where the identity of a particular Cichla species is in doubt. Unfortunately many of the specimens produced on fish farms are hybrids, so positive identification in some cases may be impossible.
Peacock Bass are native to the Orinoco and Amazon river basins of tropical South America where they may be found in both rivers and lakes. Most species prefer deep water areas with a steady current, but some species may be found in sluggish lagoons while others favour fast-flowing rapids.
They have also been introduced to other parts of the world as well, with varying results. Usually the Peacock Bass were introduced as food and sport fish, their value on both counts being exceptionally high thanks to flavourful flesh and strong fighting abilities when hooked. But they have also been used as biological control, being among the better predators where fish with spiny fins, such as tilapia, need to be controlled. Peacock Bass are used in precisely this way in Florida, for example.
On the other hand, Peacock Bass are aggressive predators with the potential to disrupt ecosystems. In some cases Peacock Bass have dramatically altered the abundance of native fish species in the rivers and lakes where they were introduced.
Aquarium size and filtration
Given that Peacock Bass can reach lengths of at least 50 cm in captivity and often significantly more, these active and fast-growing fish will need an exceptionally large aquarium. Realistically, we're talking about a tank at least 250 cm in length and 100 cm in width. Assuming a depth of 100 cm as well, that works out at an aquarium volume of 2,500 litres or 550 Imperial gallons. Obviously juveniles could be housed in smaller systems, but the growth rate of these fish should not be underestimated, and investing in a big tank up front will remove the need to upgrade down the line.
Obviously a big aquarium with big fish will need a big filter as well. External canister filters make the most sense here, though other types of filtration may be acceptable provided water quality is maintained. These are big fish with hearty appetites, and keeping the nitrite and ammonia levels at zero will be difficult without robust filtration. Aim for water turnover rates of at least 6 times the volume of the tank per hour, and ideally 8-10 times.
As with all cichlids, nitrate is the invisible killer, so regular water changes will be essential. Cichlids in general become prone to problems like dropsy if nitrate level stays above 40 mg/l and ideally the nitrate level should be kept below 20 mg/l. Overstocking and overfeeding will tend to raise nitrate levels, and both should be avoided. Similarly, any uneaten food should be removed promptly.
All Peacock Bass are outstanding jumpers, and the aquarium must have a secure, heavy lid that will prevent them from jumping out.
Water chemistry and temperature
Peacock Bass are not especially fussy about water chemistry. As South American fish, they are naturally found in water that is soft and slightly acidic, but moderately hard water seems to cause them no harm. Because very soft, very acidic water tends to diminish the effectiveness of biological filtration, such water conditions should probably be avoided. So for best results, aim for 2-15 degrees dH, pH 6.5-7.5.
Water temperature requirements are a bit more challenging. Peacock Bass do best kept quite warm, 25-28 C/77-82 F, and the warmer the water, the less oxygen it contains. Because the oxygen concentration is a bit lower than is normally the case in freshwater aquaria, it's important that the tank isn't overstocked and that there's adequate circulation of the water in the tank.
Whereas the majority of cichlids feed from the bottom, Peacock Bass are midwater predators. They hunt by sight, and when prey is spotted, they use their remarkable speed and stamina to chase their prey like wolves. Mostly they feed on smaller fish, and under aquarium conditions it should be assumed that they will eat any tankmates they can swallow.
Nonetheless, Peacock Bass are not obligate piscivores and can be maintained on a range of foods including good quality carnivore pellets such as Hikari Cichlid Gold. Farmed specimens are particularly adaptable and will snap at almost any meaty food that drifts into range, including earthworms, squid, mussels, prawns and small pieces of fish fillet. Peacock Bass often enjoy surprisingly small prey, and adults will happily eat things as small as bloodworms and krill! Obviously big specimens would need to eat a lot of these to stay healthy, but as occasionally treats these are a fine way to add variety to a diet based mostly around pellets and seafood.
Wild-caught specimens are fussier, and may need to be given live foods initially, perhaps earthworms and river shrimps in the case of older specimens and smaller invertebrates like bloodworms in the case of juveniles.
As ever with predatory fish, thiaminase and fat intake will need to be minimised. Frozen mussels, shrimps and prawns are notoriously rich in thiaminase so shouldn't be used more than once or twice a week (river shrimp can be gut-loaded with flake food, offsetting their thiaminase content to some degree). Some types of fish contain high levels of fat and thiaminase, including carps such as goldfish and minnows, and these should be avoided entirely. The best fish fillet to use is probably tilapia, which is not only thiaminase-free but also widely sold and inexpensive.
Peacock Bass are boisterous rather than psychopathic, and can be kept in groups as well as alongside suitably robust tankmates. Oddly perhaps for some of the biggest cichlids in the world, they can be bullied by aggressive cichlids like many of those from Central America, and they're best kept away from other cichlids to minimise the risk of territorial disputes. About the only cichlid species that consistently works well with Peacock Bass is the Oscar, assuming of course that they're both of similar size and that the tank is big enough for both to feel at home.
The best tankmates will be big fish that keep away from the middle part of the tank. Large L-number catfish are obvious choices, for example Panaque species, as well as medium to large sized thorny catfish like Megalodoras uranoscopus. Clown Loaches can work well, too, as can some of the bigger bichirs, though both of these will need supplementary feeding at nighttime if they can't feed properly during the day when the Peacock Bass are swimming about. Stingrays have been kept with Peacock Bass, but because Stingrays are so sensitive to water quality problems, this is an option only for the most expert aquarist.
Finding midwater and surface-swimming tankmates can be tricky because Peacock Bass are so active and likely to steal any food before such tankmates got to it. Some success has been had with Arowana, but these are big, demanding fish in their own right, and at least some species can be very aggressive. Similarly North American Gar (Lepisosteus and Atractosteus spp.) have been kept with Peacock Bass, but Gar are skittish and easily damaged if scared, so combining them with such boisterous tankmates is risky.
Sexual dimorphism and breeding
Sexual dimorphism is slight, though older males may develop nuchal humps and tend to be larger than females of equivalent age. As with most other cichlids, inspection of the genital papillae is the best way to establish gender, the male having a longer, narrower spawning tube than the female.
All Peacock Bass form strongly bonded pairs that lay their eggs on the substrate, typically on a flat object like a stone. Up to 4000 eggs may be produced, and the parents will look after their offspring for up to two months after spawning. The fry grow very rapidly and will attain a length of almost 30 cm within a year, at which point they will be sexually mature.
Although regularly bred on fish farms in ponds, breeding under home aquarium conditions is very difficult because of space needed for a territorial pair.
Common Peacock Bass Cichla occelaris
This is the most widely traded species. They are very attractive fish with silvery-green to yellowy-green bodies, three dark, vertical bands on the flanks, and an obvious eyespot on the base of the tail fin. Unlike some of the other species that have reddish ventral, anal and tail fins, the equivalent fins of Cichla occelaris are basically greenish-yellow. There is usually a horizontally extended patch of small black blotches behind the pectoral fin. Under aquarium conditions adult length is around 50-60 cm, though this species can get considerably larger.
In terms of social behaviour this species is fairly easy-going and one of the better Peacock Bass for mixed species set-ups.
Compared to Cichla occelaris, Cichla monoculus has much shorter vertical bars on its flanks. Whereas those on Cichla occelaris extend from the dorsal surface most of the way down each flank, the three vertical bars on Cichla monoculus are little more than elongate blotches below the dorsal fin and do not extend even as far as the lateral line. During breeding this species develops brilliant red markings across the throat, ventral fins, anal fin and the lower lobe of the tail fin. Like Cichla occelaris, this species has some black blotches behind the pectoral fin.
Like Cichla occelaris, Cichla monoculus is pretty mild given its size, and a good choice for mixed species aquaria when kept alongside tankmates too large to swallow whole.
Orinoco Peacock Bass Cichla orinocensis
Cichla orinocensis is a distinctive species with three roughly circular eyespots on its flanks rather than vertical bands. These are more or less in line with the eyespot on the base of the tail, and all are edged with a ring of silvery scales. Sexually mature specimens will develop reddish colouration across the ventral surface when spawning, particularly along the throat, ventral fins, anal fin, and the lower lobe of the tail fin.
This is one of the more aggressive Peacock Bass, and does best either singly on in large, preferably odd-numbered groups that allow tensions to be diffused among all the specimens. When kept in twos or threes bullying is common. This species can be equally hard on other types of tankmate, including other Peacock Bass species. A challenging, if beautiful, species.
This species resembles Cichla occelaris in terms of colour, but whereas that species has consistently elongate vertical bands on its flanks, the three bands on this species are irregular in shape, often pinched or divided so that each band is actually two or more elongate blotches. Younger specimens tend to have several horizontal rows of white spots that run from head to tail, but as the fish matures these tend to disappear.
Cichla pinima is quite an easy-going species comparable to Cichla occelaris in terms of compatibility.
Speckled Peacock Bass Cichla temensis
This is the biggest of the Peacock Bass, with wild specimens reported to have reached lengths of up to 99 cm and weights up to 12.2 kg. Under aquarium conditions this species does not get quite so big, but as with other Peacock Bass, the aquarist should "assume the worst" and plan around keeping one or more specimens that may be 60-70 cm in length.
Colouration is difficult to state categorically for two reasons. Firstly, the species is intrinsically variable, and secondly, many of the specimens offered for sale are hybrids. But in general this species has a longer, narrower body shape to other Cichla species; a yellowy-green to silvery-green body colour; three black vertical bands on its flanks; a pattern of black blotches between the eye and gill cover; and reddish colouration to the ventral fins, anal fin, and the lower lobe of the tail fin. Juveniles have a scattering of white spots on the head, body and fins, and in some cases these persist on adults.
Cichla temensis is one of the most aggressive Peacock Bass and best kept in single-species set-ups, either alone or in large, odd-numbered groups. It shouldn't be kept with other Peacock Bass, and tankmates such as catfish should be chosen with care.
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