Transcriptomic response to aquaculture intensification in Nile tilapia

Area of Science:

• Aquaculture
• Animal Behavior
• Genomics

Background:

• Global demand for fish protein necessitates aquaculture intensification.
• Understanding genetic adaptations for high-density fish farming is crucial.
• Nile tilapia exhibit social structure shifts with increasing density.

Purpose of the Study:

• To investigate the transcriptomic response to aggression and crowding in Nile tilapia.
• To identify genetic changes associated with reduced aggression and adaptation to high densities.
• To explore the neuroendocrine pathways involved in social stress coping.

Main Methods:

• Quantified aggression and skin darkening (stress proxy) using a mirror test.
• Analyzed gene expression in the hypothalamus of aggressive and nonaggressive fish at different densities.
• Compared gene expression profiles between fish reared at low and high densities.

Main Results:

• Fish at high density were less aggressive, darker, had larger brains, and showed gene expression indicative of a reactive stress-coping style and activated hypothalamus-pituitary-interrenal (HPI) axis.
• Gene expression differences in aggressive fish were linked to density and aggression levels.
• Gene expression in nonaggressive fish correlated with skin brightness and social stress.

Conclusions:

• Crowding response in Nile tilapia is context-dependent, involving different neuroendocrine pathways based on social status.
• Identifying genes related to crowding response can aid in selecting nonaggressive, stress-tolerant fish for aquaculture.
• This knowledge supports more efficient fish domestication for sustainable aquaculture intensification.