Reliable, precise, and easy-to-use aquarium heaters. Tropical freshwater and marine fish require a stable temperature of around 24-27C, in order to remain healthy and in good condition. The Tetra HT range of heaters maintain a constant temperature via an in-built thermostat, making it easy to provide the correct conditions. Glass. Fish tank capacity 30 litres. Suitable for marine fish. Accessories include: heater, . Overall size H28, W9, D5cm. Weight 0.31kg. Manufacturers 2 year guarantee.