King British Tubifex Treats are suitable for all aquarium fish, plus turtles and terrapins. They are a natural river-dwelling worm, harvested, then freeze-dried immediately to retain flavour & nutritional value. King British Tubifex Treats are suitable for all aquarium fish, plus turtles and terrapins. They are a natural river-dwelling worm, harvested, then freeze-dried immediately to retain flavour & nutritional value. We press the dried worms into one centimetre cubes, making them easier to feed to your fish. Tubifex is the type of food that a fish would choose to eat in the wild, and provides a welcome treat and protein-rich nutritional supplement to any fish.