Increasing water temperature due to global warming has decreased the aquaculture
production of tilapia in the Philippines. Stress is the initial effect of increasing temperature, but
when stress prolongs and not predicted nor prevented, fish health is suppressed and may lead to
mortality. Thus, stress indication is of premium importance. In order to provide a more
convenient and reliable stress indication, this study had reported a morphological response
parameter (body darkening) as a thermal stress indicator and used other established parameters
to determine their associations and reliability. Results suggested that body darkening and all
other stress indictors were positively and significantly related to water temperature. Particularly,
80.50% of the variations in body darkening scores were brought by the changes in water
temperature. More so, body darkening revealed highly significant positive relationships with
the darkening of the eye (ρ = 0.902, p <0.000, n =22), ventilation rates (ρ = 0.902, p <0.001, n
=22), and cortisol levels (ρ = 0.868, p <0.001, n =22). Similar to other known stress indicators
for fish, body darkening is likewise a realible, convenient, sensitive, and a non-invasive stress
indicator.
Keywords
Ventilation, Indication, Cortisol, Eye color pattern
INTERNATIONAL JOURNAL OF AGRICULTURAL TECHNOLOGY
Published by : Association of Agricultural Technology in Southeast Asia (AATSEA) Contributions welcome at : http://www.ijat-aatsea.com
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