The awesome Golden Wonder Killifish! These killis grow to be about 3-4 inches long. They are a peaceful fish with the only aggression being territorial between males. They should be kept with fish that they can not swallow since they are a predatory species that will eat any fish small enough. Being a carnivorous fish, Golden Wonder Killis should be fed meaty foods such as frozen brine shrimp, bloodworms and mysis shrimp.