This 19 August 2019 video from Artis zoo in Amsterdam in the Netherlands says about itself (translated):
At the moment you can see young Banggai cardinalfish in the Aquarium. The eggs are hatched by their father, he does that with his mouth. After about four weeks, he will release the youngsters between the safe spines of the Diadema setosum sea urchin. The fish stay close to this sea urchin their entire life because it protects the fish. As soon as danger threatens, they retreat between the spines.
This threatened fish species lives in Indonesia.
