Euphyllia frogspawn paradivisa Green with purple tips These corals are a wonderful addition to the aquarium, and available in all shapes, sizes and colours. A hammerhead or bladder coral is basically quite easy to keep, even for beginners. The coral grows best if the water parameters are good, which means that there must be a small amount of phosphate and nitrate present, and of course the rest of the water parameters must also be in order. These corals feed on light (preferably T5), but can also be fed different kinds of dust food, and of course artemia and mysis.