Can Tropical Fish Survive Without Heaters And Live In Cold Water?

Can tropical fish survive without heaters and live in cold water

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Fish are poikilothermic. Unlike mammals and birds, they cannot generate their own body heat and rely on the temperature of the water to keep their bodies at the optimum temperature for their metabolism to function.

Fish fall broadly into three temperature categories:

Cold - these are fish that can live out of doors in a British winter and can survive easily below 18 ^oC. This group is usually pond fish, which includes common goldfish and koi.

Temperate - these are fish that require slightly warm water, between 18 and 22 ^oC. This group includes fish such as fancy goldfish and white cloud mountain minnows.

Tropical - these fish need a temperature above 22^oC. This group includes almost all the fish for sale.

Temperate fish can be kept without a heater, provided the air temperature of the room never falls below 18^oC on the coldest winter night. However, it is always safer to have a heater in the tank as a back up should the room temperature fall too low.

Tropical fish should always have a heater in the tank, rated at 1 watt per litre of tank water. Should the tank volume fall between heater ratings, the next higher watts should be purchased. Very large tanks will need two heaters, one at each end of the tank.

If fish are kept in water that is too cold, their metabolism slows down and the fish will not be healthy. Conversely, when fish are kept in water that is too warm, their metabolism is too fast and they will live a shortened life span.

Look at the fish profiles for the temperature required by any species of fish, or ask in the forum.