In News:

A new species of groundwater-dwelling fish, Gitchak nakana, has recently been discovered in Assam. The species was found in a dug-out well and represents the first aquifer-dwelling (phreatobitic) fish recorded from Northeast India. This discovery adds to India’s growing record of endemic and subterranean biodiversity.

About Gitchak nakana

• Type: Groundwater (aquifer-dwelling) fish
• Family: Cobitidae (Loaches)
• Genus: Newly described genus
• Size: Approximately 2 cm in length
• Habitat: Subterranean aquifers
• Location of Discovery: Assam

The species was discovered in a dug-out well, indicating its existence in underground water systems rather than surface water bodies such as rivers or ponds.

Etymology

The name reflects local linguistic heritage:

• “Gitchak” (Garo language) – means red, referring to its striking blood-red colour when alive.
• “Na-tok” / “kana” – refer to a blind fish.

The nomenclature highlights both the species’ morphology and its cultural-geographical context.

Unique Morphological Features

Gitchak nakana displays classic troglomorphic adaptations — traits evolved for life in complete darkness:

• Absence of externally visible eyes (blindness)
• Translucent, pigmentless body
• Extreme miniaturization (only 2 cm long)
• Complete absence of skull roof — the brain is covered dorsally only by skin

The lack of a skull roof is particularly unusual and makes it one of the most anatomically distinctive loach species recorded.

What are Phreatobitic Species?

• Phreatobitic organisms live in groundwater aquifers rather than surface water or caves.
• Aquifers are underground water-bearing geological formations.
• Such habitats are difficult to access and poorly studied, which explains why discoveries are rare.

Globally:

• More than 300 fish species are known from subterranean habitats.
• However, the vast majority inhabit caves.
• Less than 10% are known from groundwater aquifers, making this discovery scientifically significant.

Thus, Gitchak nakana represents a rare addition to the small global group of true aquifer-dwelling fishes.