The Biology and Culture of Tilapias

Environmental Physiology of Tilapias

Fish and Aquaculture Research Station

Dor, D.N.

Hof Hacarmel, Israel

CHERVMSKI. J. 1982. Environmental physiology of tilapias, p. 119-128. In

R.S.V. Pullin and R.H. Lowe-McConnell (eds.) The biology and culture of

tilapias. ICIJARM Conference Proceedings 7, 432 p. International Center

for Living Aquatic Resources Management, Manila, Philippines.

Tilapias in general do not grow at water temperatures below 16OC and are

not able to survive water temperatures below lo0C for than a few days. Low

water temperature tolerance limits are: Tilapia sparrmanii 7OC, T. rendalli

ll°C, Sarotherodon aureus 8-8.5'~, S. vulcani 11-13'~ and S. mossambicus

8-10'~. Hybrids between S, niloticus, S. vulcani, S. hornorum and S. aureus

are similar to S. aureus in their low temperature tolerance. Low temperature

tolerance is affected by prior acclimation temperatures. Tilapias are tolerant

to high water temperatures, e.g., 42O~ for S. alcalicus grahami and 41°C for

S. aureus. Tilapias are euryhaline and are able to survive, grow and some

species even reproduce in sea water up to 40%o~alinity. The lowest dissolved

oxygen concentrations survived for short periods by tilapias are 0.1 ppm for

S. mossambicus and 0.2 ppm for S. aureus. Tilapias are able to tolerate a

pH range of 5 to 11. S. aureus tolerates a maximum of 2.4 mgll un-ionized

ammonia but after exposure to sublethal concentrations can raise this limit

to 3.4 mgll.

Introduction

Fish of the genera Tilapia and Sarotherodon are native to Africa and
Israel, the northern limit of their distribution. The tropical origin of tilapias
is clearly expressed in their ecological physiology, especially in their tem-
perature preference during their reproductive period.
Tilapias become inactive at water temperatures below 16"C, which is the
minimal temperature for normal growth. Reproduction occurs above 22°C.
Their adaptation to stable ambient temperature regimes has limited their
natural distribution to tropical areas.
In recent years tilapias have been distributed all over the world where
temperatures are suitable for their growth and reproduction. In many parts of
the world tilapias have been introduced for vegetation control, pond culture
and recreational fishing. They have become established in numerous lakes in
Florida, California and Texas where winter temperatures are not limiting.