In this study we verified data of water temperatures collected by CORSAN-RS from 1996 to 2004 in several cities of the state of Rio Grande do Sul, southern Brazil, and analyzed the possibility of raising the most cultivated fish species in Brazil. The water temperature from 1996 to 2004 was 16 to 28ºC in summer, 17 to 23ºC in fall, 14 to 17ºC (down to 9ºC in the coldest months) in winter and 14 to 21ºC in spring. Native species of this state, such as silver catfish (Rhamdia quelen), traíra (Hoplias malabaricus), dorado (Salminus brasiliensis), pintado (Pimelodus maculatus), as well as carps (family Cyprinidae), are resistant to the low winter temperatures. These species have a lower growth rate in coldest months (winter/spring) but a good development in warmer months (summer/fall), reaching a satisfactory performance throughout the year. In the periods of more intense cold, mortality of some introduced species, such as surubim from Amazon Basin (Pseudoplatystoma sp.), pirapitinga (Piaractus brachypomus), pirarucu (Arapaimas gigas), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) and Nile tilapia (Oreochromis niloticus) may occur. In addition, as most tropical species have a thermal range for growth and reproduction between 20 to 28ºC, some species may have poor development even in fall. Therefore, water temperature in this state should be considered in the choice of fish species to be cultivated.
Fish growth; Mortality; growth; Freshwater fish; Water temperature
