Background

The bichiques, also known as Sicydium punctatum and Sicydium plumieri, are two species of gobiid fish found in the rivers of the Caribbean, particularly in Guadeloupe. These amphidromous species, which migrate between fresh and salt water during their life cycle, are important indicators of the health of river ecosystems. They play a key role in the trophic networks of these environments.

Description

Physical characteristics :

Size :

• Sicydium punctatum : on average 5 to 7 cm.
• Sicydium plumieri : on average 10 to 12 cm.

Appearance :

• Sicydium punctatum : Elongated body, brownish to grayish coloration, marked with small black spots.
• Sicydium plumieri : Elongated body, bright coloration with shades of blue, green, and yellow.

Morphology

These fish possess a pelvic suction disc formed by the fusion of their pelvic fins, allowing them to cling to rocks in fast-flowing rivers. Their mouth is inferior, adapted for scraping algae from hard surfaces.

Common Names

• Sicydium punctatum and Sicydium plumierin : These species are generally called “bichiques” or “pichiques” in Guadeloupe and other Caribbean islands. Adults are sometimes referred to as “cabots.”

Habitat

These species are mainly found in fast-flowing rivers, often at high altitudes, where the waters are well oxygenated and the riverbeds are rocky. They prefer areas with waterfalls and rapids, where they can feed on biofilms of algae and microorganisms growing on rocks.

Lifestyle

Reproduction :

Females lay their eggs in freshwater. Once the eggs hatch, the larvae are carried downstream to the sea, where they develop before migrating back into rivers as juvenile fish. This migratory process is essential for their survival.

Diet :

These fish feed mainly on algae, diatoms, and other organic matter, which they scrape from rocks using their specialized mouth.

Behavior :

Bichiques are primarily diurnal and act as grazers, cleaning algal growth from rock surfaces. Their pelvic suction disc is a crucial adaptation that enables them to remain attached to rocks despite the strong currents.

Ecology and Interactions

• Ecological role :
  Sicydium species play a key role in controlling algae within river ecosystems, helping maintain ecological balance. Their presence also supports biodiversity by providing feeding niches for other species.
• Predation :
  Juvenile bichiques (larvae and fry) are an important food source for many predators in both freshwater and marine environments. Adults can also fall prey to larger fish, piscivorous birds, and other predators.

Cultural and Economic Importance

Bichiques hold significant cultural and gastronomic value in the Caribbean, particularly in Guadeloupe and Réunion Island. Juveniles are harvested in large quantities during their migration from the sea to rivers and are considered a local delicacy. Bichique fishing is a traditional activity that forms part of the local cultural heritage.

Conservation and Threats

Populations of Sicydium punctatum and Sicydium plumieri are threatened by several factors:

• Habitat loss: Dam construction and sand extraction alter natural habitats, making migration difficult and disrupting their life cycle.
• Pollution: Chemical and organic pollutants in rivers degrade water quality and can be toxic to these sensitive species.
• Climate change: Altered rainfall patterns and rising water temperatures affect habitats and food availability.

Protection measures :

Conservation efforts include protecting river habitats, regulating bichique fishing to prevent overexploitation, and initiatives to maintain water quality in rivers. Preserving ecological corridors that allow migration between marine and riverine environments is crucial for their survival.

Sources

Rapport final du programme “Sicydium sentinelle” (Synthèse du programme)

The goby fish Sicydium spp. as valuable sentinel species towards the chemical stress in freshwater bodies of West Indies

Variation in reproductive strategies of two amphidromous gobies of the West Indies: Sicydium plumieri and Sicydium punctatum