Brook Trout can only survive in a narrow band of temperatures (FWS).
In contrast to eurytherms, senothermic fish can only function in a narrow range of water temperatures. Brook Trout (Salvelinus fontinalis), for example, function optimally approximately between 13 and 18 degrees Celsius. This thermoregulatory strategy requires that organs, enzymes, and metabolic processes operate in a small temperature band and makes these fish particularly vulnerable to environmental changes.