Can clownfish kill an anemone? Unfortunately, YES.
They have an amazing symbiotic relationship, clownfish and anemones. Clownfish help to feed anemones and allow more oxygen and nutrients to circulate between the anemone’s tentacles. This occurs when they swim through them opening up the spaces between the tentacles so more oxygenated and nutrient rich water can reach them. Not only that but they are fiercely territorial, especially when looking after eggs, which in turn helps keep the anemone safe.
Anemones offer clownfish protection due to their stinging tentacles. They keep would-be predators of the clownfish at bay. For those that are small enough or unlucky enough to venture too close, they are stunned and killed by the toxic substance produced by the anemone.
Clownfish have a thick slime coat over their bodies that protect them from the sting of the anemone’s tentacles. Even so, most anemones will need to acclimate themselves to the sting of the anemones before becoming fully immune.
However, just because they have this special relationship, it doesn’t mean that all clownfish are the right match for all types of sea anemones.