Spawning substrate preference and spawning behavior of chocolate mahseer, Neolissochilus hexagonolepis

Area of Science:

• Aquaculture and Ichthyology
• Fish reproductive biology
• Conservation genetics

Background:

• Captive breeding programs are crucial for restoring endangered fish populations.
• Neolissochilus hexagonolepis (N. hexagonolepis) requires effective captive spawning methods for conservation.
• Understanding substrate preferences and spawning behaviors is key to successful artificial propagation.

Purpose of the Study:

• To investigate substrate type and area for enhancing N. hexagonolepis spawning in captivity.
• To describe the spawning behaviors of male and female N. hexagonolepis.
• To develop a viable egg production technique for N. hexagonolepis.

Main Methods:

• Evaluated three substrates: gravel, small cobble, and coarse sand, for spawning.
• Observed and documented male and female spawning behaviors, including substrate preparation and courtship.
• Compared egg collection efficiency between siphoning and stripping methods.

Main Results:

• N. hexagonolepis showed a preference for gravel and cobble substrates, avoiding sand.
• Females prepared spawning pits, and males exhibited courtship and aggressive behaviors.
• Stripping yielded significantly higher egg collection and successful fertilization (90.3%), hatching (82.8%), and larval survival (97.4%) rates compared to siphoning.

Conclusions:

• Gravel substrate trays are a feasible method for N. hexagonolepis egg production in captivity.
• The study provides the first data on volitional spawning of N. hexagonolepis using substrates.
• Findings support environmental management for population enhancement and viable captive breeding techniques.