Classification Tetraodontidae Distribution Endemic to the state of Kerala, India. Habitat An exclusively freshwater species usually inhabiting sluggish, heavily-vegetated inland waters. Maximum Standard Length Achieves a tiny adult size of only 1″ (2.5cm). Aquarium SizeTOP ↑ You could keep a single fish in a tank as small as 12″ x 8″ x 8″ 30cm x 20cm x 20cm – 12.6 litres. If you want to keep a group more space is needed.