From the Greek stenos - narrow and therme - heat, heat.

Stenothermic fish are fish that can live only at a narrow amplitude of ambient temperature fluctuations. They are usually inhabitants of tropical and arctic water bodies, as well as deep water, living in an environment with little temperature variation.

Marine and soil animals that can live only at a certain or narrowly variable temperature. The temperature of the environment to which stenothermic animals are adapted is different for different species: thermophilic animals can live only at relatively high temperatures, usually not lower than 20 °C (e.g., reef corals), cold-loving - at low temperatures, sometimes close to 0 °C (e.g., some species of Arctic crustaceans, salmon fish, a number of species of seals, etc.).Stenothermic animals are opposed to eurythermal animals.