The Antarctic fish Pagothenia borchgrevinki has been shown to be able to survive at raised temperatures. Cardiac filling in vertebrates is influenced by venous return which itself is influenced by pressures in the major veins. The effect of temperature on venous return to the heart was investigated by cannulating the ductus cuvieri (major vein entering the heart) and the dorsal aorta and measuring the blood pressure at rest, during exercise and following an increase in temperature.
Sandblom, E. Axelsson, M. Davison, W. 2008 Enforced exercise, but not acute temperature elevation, decreases venous capacitance in the stenothermal Antarctic fish Pagothenia borchgrevinki. Journal of comparative physiology B 178: 845-851 DOI 10.1007/s00360-008-0272-x
Sandblom, E., Axelsson, M. And Davison, W. 2008. Circulatory function at sub-zero temperature: venous responses to catecholamines and angiotensin II in the Antarctic fish Pagothenia borchgrevinki. Journal of Comparative Physiology B 179: 165-173.