Yellow peacock bass

Language English

Onglets

Description

Distinguishing features

While not at all related, yellow peacock bass resemble smallmouth bass, with the addition of three black vertical lines on each side of the body and a black spot at the base of the tail.

Like smallmouth bass, they have two fused dorsal fins, the first with hard rays (spiny dorsal fin) and the second with soft rays (soft dorsal fin).

The genus Cichla contains 15 species known as peacock bass (or tucunare). Among these yellow peacock bass is considered a small size species, even though it can grow up to 45 cm in length.

Reproduction

For reproduction, yellow peacock bass couples build two to four nests out of small rocks on the riverbed, but the female does not lay her eggs directly inside. Instead, she will lay between 5,000 and 7,000 eggs on a solid substrate nearby. When the eggs hatch, the parents use their mouths to move the young to the nests.

For two months, the parents protect the eggs and then the fry, until they are 3.5 cm long. The female stays close to the nests while the male patrols the area, chasing off any intruders who come too close.

When the parents stop protecting their young, the fry form small groups that seek shelter in the dense vegetation near the riverbank.

Diet

A piscivorous (fish-eating) species, peacock bass are voracious predators at the higher levels of the food chain.

This fish is a very active hunter that relentlessly pursues its prey. It is so voracious that when introduced into a body of water for sport fishing, it can easily become a threat to local species.

Predators

As the yellow peacock bass is a large fish, reaching up to 45 cm in length, it has very few potential predators as an adult. These include the giant river otter (Ptenoura brasiliensis), the boto or Amazon river dolphin (Inia geoffrensis), caimans, and humans.

Peacock bass (Cichla sp) is a highly sought-after sport fish in the Amazon, particularly the larger species such as C. temensis, C. monoculus, and C. ocellaris. Several species of these fish, most commonly the yellow peacock bass, have been introduced in southeastern Brazil to meet the demands of anglers.

Peacock bass is consumed locally, as its flesh is delicious. However, it should be eaten in moderation, as its flesh contains high levels of mercury. Local health authorities recommend opting for herbivorous species, which are less contaminated by mercury, such as tambaqui.

Habitat

Yellow peacock bass is native to the clearwater rivers of the Tocantins River Basin and its tributary, the Araguaia River, in the Lower Amazon (Brazilian states of Pará and Tocantins).

This tropical fish lives near the banks of rivers, among vegetation, branches and other submerged objects, where they find refuge. During the rainy season, they inhabit clearwater flooded forests called igapós.

Ecology, behaviour

Peacock bass are rather sedentary. They can migrate when prey becomes scarce, but will not venture more than 40 kilometers away.

They tend to be very territorial, especially when defending their nests and young. They will not allow any other fish to approach.

Where does the mercury in peacock bass come from?

In the 1980s, a Canadian-Brazilian research team, which included Robert Davidson, a researcher at the Biodome, highlighted the link between deforestation in the Amazon and the contamination of waterways by mercury. They discovered that the exposure of soils allowed the release of mercury that had accumulated naturally over thousands of years.

The mercury, carried by rain, ends up in the aquatic environment, where it becomes part of the food chain in the form of methylmercury.

Piscivorous species like peacock bass accumulate the highest levels of mercury. This process is known as trophic magnification. Here’s how it works:

Methyl mercury is first absorbed by aquatic plants. Since it is difficult for an organism to eliminate this substance, herbivores absorb the mercury that has accumulated in the plants. The carnivores that feed on these herbivores accumulate the mercury contained in their prey. Carnivores further up the food chain, like peacock bass, feed on these small carnivores and thus contain the highest levels of mercury.

French name

Tucunaré jaune

Scientific name

Cichla kelberi

Phylum

Chordata

Class

Osteichthyes (bony fish)

Order

Perciformes

Family

Cichlidae

Size

Up to 45 cm long

Weight

Up to 1.5 kg

Life span

Estimated at between 10 and 15 years

Status

Least concern (IUCN 2017)

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