Temperatures selected by Tilapia mossambica (Peters) in a test tank with a horizontal temperature gradient
Unexplained high mortality ofTilapia mossambica (Peters) has at times been noted during winter in dams on the South African Highveld and prompted an investigation into the temperature tolerance and temperature preference of this species. This work deals with the temperature selected by the fish. The history of temperature selection experiments is outlined and a relatively simple technique of establishing a temperature gradient in a horizontal test tank is described. Results obtained with juvenile fish previously acclimated to various controlled temperatures showed that these fish selected a range of temperatures of 27.0°C to 33.5°C, with a theoretical median selection temperature of 28.5°C. The findings are discussed with reference to previous relevant literature. It is concluded thatT. mossambica was a thermophilic species which could succumb during cold spells in the Highveld dams.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie
- 4 - phytopathologie. zoologie agricole. protection des cultures et des forets